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diff --git a/doc/Scenarios.html b/doc/Scenarios.html index c8bb154..8cd45c9 100644 --- a/doc/Scenarios.html +++ b/doc/Scenarios.html @@ -1,134 +1,134 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> -<html> - <head> - <title>Argyll Usage Scenarios</title> - <meta http-equiv="content-type" content="text/html; - charset=windows-1252"> - </head> - <body> - <h2><u>Typical usage Scenarios and Examples</u></h2> - Choose a task from the list below. For more details on alternative - options, follow the links to the individual tools being used.<br> - <br> - Note that by default it is assumed that ICC profile have the file - extension <span style="font-weight: bold;">.icm</span>, but that on - Apple OS X and Unix/Linux platforms, the <span style="font-weight: - bold;">.icc</span> extension is expected and should be used.<br> - <h4><a href="#PM1">Profiling Displays</a></h4> - <h4> <a href="#PM1a">Checking you can access your - display<br> - </a></h4> - <h4> <a href="#PM1b">Adjusting and Calibrating a - displays</a></h4> - <h4> <a href="#PM1c">Adjusting, calibrating and - profiling in one step<br> - </a><span style="font-weight: bold;"></span><span - style="font-weight: bold;"></span><span style="text-decoration: - underline;"></span></h4> - <h4> <a href="#PM2">Creating display test values</a></h4> - <h4> <a href="#PM3">Taking readings from a - display</a></h4> - <h4> <a href="#PM4">Creating a display profile</a></h4> - <h4> <span style="text-decoration: underline;"></span><a - href="#PM5">Installing a display profile</a></h4> - <h4> <span style="text-decoration: underline;"></span><a - href="#PM6">Expert tips when measuring displays</a></h4> - <h4> <span style="text-decoration: underline;"></span><a - href="#PM7">Calibrating and profiling a display that doesn't - have VideoLUT access.</a></h4> - <h4><br> - <a href="#PS1">Profiling Scanners and other input devices such as - cameras<br> - </a></h4> - <h4> <a href="#PS2">Types of test charts</a></h4> - <h4> <a href="#PS3">Taking readings from a - scanner</a></h4> - <h4> <a href="#PS4">Creating a scanner profile</a></h4> - <h4><br> - <a href="#PP1">Profiling Printers</a></h4> - <h4> <a href="#PP2">Creating a print profile - test chart</a></h4> - <h4> <a href="Scenarios.html#PP2b">Printing a - print profile test chart</a></h4> - <h4> <a href="#PP3">Reading a print test chart - using an instrument</a></h4> - <h4> <a href="#PP4">Reading a print test chart - using a scanner</a></h4> - <h4> </h4> - <h4> <a href="#PP5">Creating a printer profile<br> - </a></h4> - <h4> <a href="#PP6">Choosing a black generation - curve</a></h4> - <br> - <h4><a href="Scenarios.html#PC1">Calibrating Printers</a></h4> - <h4> <a href="Scenarios.html#PC2">Calibrated - print workflows</a></h4> - <h4> <a href="Scenarios.html#PC3">Creating a - print calibration test chart</a></h4> - <h4> </h4> - <h4> <a href="Scenarios.html#PC4">Creating a - printer calibration<br> - </a></h4> - <h4> <a href="Scenarios.html#PC5">Using a printer - calibration</a></h4> - <h4> <a href="#PC6">How profile ink limits are - handled when calibration is being used<br> - </a></h4> - <h4> <a href="#LP1">Linking Profiles</a></h4> - <p> <b><a href="#LP2">Image dependent gamut - mapping using device links</a></b><br> - </p> - <p> <b><a href="#LP2">Soft Proofing Link</a></b><br> - </p> - <h4> <a href="#TR1">Transforming colorspaces of raster files</a></h4> - <h4></h4> - <h4> <a href="#TV1">Creating Video Calibration 3DLuts</a></h4> - <h4><a href="Scenarios.html#TV2">Verifying Video Calibration 3DLuts</a></h4> - <br> - <hr style="width: 100%; height: 2px;"><br> - <h3><a name="PM1"></a>Profiling Displays</h3> - Argyll supports adjusting, calibrating and profiling of displays - using one of a number of instruments - see <a - href="instruments.html">instruments</a> for a current list. - Adjustment and calibration are prior steps to profiling, in which - the display is adjusted using it's screen controls, and then - per channel lookup tables are created to make it meet a well behaved - response of the desired type. The process following that of - creating a display profile is then similar to that of all other - output devices :- first a set of device colorspace test values needs - to be created to exercise the display, then these values need to be - displayed, while taking measurements of the resulting colors using - the instrument. Finally, the device value/measured color values need - to be converted into an ICC profile.<br> - <br> - <h3><a name="PM1a"></a>Checking you can access your display<br> - </h3> - You might first want to check that you are accessing and can - calibrate your display. You can do this using the <a - href="dispwin.html">dispwin</a><span style="font-weight: bold;"></span> - tool<span style="font-weight: bold;">.</span> If you just run <span - style="font-weight: bold;">dispwin</span> it will create a test - window and run through a series of test colors before checking that - the VideoLUT can be accessed by the display. If you invoke the usage - for <span style="font-weight: bold;">dispwin</span> (by giving it - an unrecognized option, e.g. <span style="font-weight: bold;">-?</span>) - then it will show a list of available displays next to the <span - style="font-weight: bold;"><span style="font-weight: bold;">-d</span></span> - flag. Make sure that you are accessing the display you intend to - calibrate and profile, and that the VideoLUT is effective (the <span - style="font-weight: bold;">-r</span> flag can be used to just run - the VideoLUT test). You can also try clearing the VideoLUTs using - the <span style="font-weight: bold;">-c</span> flag, and loading a - deliberately strange looking calibration <span style="font-weight: - bold;">strange.cal</span> that is provided in the Argyll <span - style="font-weight: bold;">ref</span> directory.<br> - <br> - Note that calibrating and/or profiling <span style="font-weight: - bold;">remote</span> displays is possible using X11 or a web - browser (see <span style="font-weight: bold;">-d</span> option of - dispcal and dispread), or by using some external program to send - test colors to a display (see <span style="font-weight: bold;">-C</span> - and <span style="font-weight: bold;">-M</span> options of dispcal +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
+<html>
+ <head>
+ <title>Argyll Usage Scenarios</title>
+ <meta http-equiv="content-type" content="text/html;
+ charset=windows-1252">
+ </head>
+ <body>
+ <h2><u>Typical usage Scenarios and Examples</u></h2>
+ Choose a task from the list below. For more details on alternative
+ options, follow the links to the individual tools being used.<br>
+ <br>
+ Note that by default it is assumed that ICC profile have the file
+ extension <span style="font-weight: bold;">.icm</span>, but that on
+ Apple OS X and Unix/Linux platforms, the <span style="font-weight:
+ bold;">.icc</span> extension is expected and should be used.<br>
+ <h4><a href="#PM1">Profiling Displays</a></h4>
+ <h4> <a href="#PM1a">Checking you can access your
+ display<br>
+ </a></h4>
+ <h4> <a href="#PM1b">Adjusting and Calibrating a
+ displays</a></h4>
+ <h4> <a href="#PM1c">Adjusting, calibrating and
+ profiling in one step<br>
+ </a><span style="font-weight: bold;"></span><span
+ style="font-weight: bold;"></span><span style="text-decoration:
+ underline;"></span></h4>
+ <h4> <a href="#PM2">Creating display test values</a></h4>
+ <h4> <a href="#PM3">Taking readings from a
+ display</a></h4>
+ <h4> <a href="#PM4">Creating a display profile</a></h4>
+ <h4> <span style="text-decoration: underline;"></span><a
+ href="#PM5">Installing a display profile</a></h4>
+ <h4> <span style="text-decoration: underline;"></span><a
+ href="#PM6">Expert tips when measuring displays</a></h4>
+ <h4> <span style="text-decoration: underline;"></span><a
+ href="#PM7">Calibrating and profiling a display that doesn't
+ have VideoLUT access.</a></h4>
+ <h4><br>
+ <a href="#PS1">Profiling Scanners and other input devices such as
+ cameras<br>
+ </a></h4>
+ <h4> <a href="#PS2">Types of test charts</a></h4>
+ <h4> <a href="#PS3">Taking readings from a
+ scanner</a></h4>
+ <h4> <a href="#PS4">Creating a scanner profile</a></h4>
+ <h4><br>
+ <a href="#PP1">Profiling Printers</a></h4>
+ <h4> <a href="#PP2">Creating a print profile
+ test chart</a></h4>
+ <h4> <a href="Scenarios.html#PP2b">Printing a
+ print profile test chart</a></h4>
+ <h4> <a href="#PP3">Reading a print test chart
+ using an instrument</a></h4>
+ <h4> <a href="#PP4">Reading a print test chart
+ using a scanner</a></h4>
+ <h4> </h4>
+ <h4> <a href="#PP5">Creating a printer profile<br>
+ </a></h4>
+ <h4> <a href="#PP6">Choosing a black generation
+ curve</a></h4>
+ <br>
+ <h4><a href="Scenarios.html#PC1">Calibrating Printers</a></h4>
+ <h4> <a href="Scenarios.html#PC2">Calibrated
+ print workflows</a></h4>
+ <h4> <a href="Scenarios.html#PC3">Creating a
+ print calibration test chart</a></h4>
+ <h4> </h4>
+ <h4> <a href="Scenarios.html#PC4">Creating a
+ printer calibration<br>
+ </a></h4>
+ <h4> <a href="Scenarios.html#PC5">Using a printer
+ calibration</a></h4>
+ <h4> <a href="#PC6">How profile ink limits are
+ handled when calibration is being used<br>
+ </a></h4>
+ <h4> <a href="#LP1">Linking Profiles</a></h4>
+ <p> <b><a href="#LP2">Image dependent gamut
+ mapping using device links</a></b><br>
+ </p>
+ <p> <b><a href="#LP2">Soft Proofing Link</a></b><br>
+ </p>
+ <h4> <a href="#TR1">Transforming colorspaces of raster files</a></h4>
+ <h4></h4>
+ <h4> <a href="#TV1">Creating Video Calibration 3DLuts</a></h4>
+ <h4><a href="Scenarios.html#TV2">Verifying Video Calibration 3DLuts</a></h4>
+ <br>
+ <hr style="width: 100%; height: 2px;"><br>
+ <h3><a name="PM1"></a>Profiling Displays</h3>
+ Argyll supports adjusting, calibrating and profiling of displays
+ using one of a number of instruments - see <a
+ href="instruments.html">instruments</a> for a current list.
+ Adjustment and calibration are prior steps to profiling, in which
+ the display is adjusted using it's screen controls, and then
+ per channel lookup tables are created to make it meet a well behaved
+ response of the desired type. The process following that of
+ creating a display profile is then similar to that of all other
+ output devices :- first a set of device colorspace test values needs
+ to be created to exercise the display, then these values need to be
+ displayed, while taking measurements of the resulting colors using
+ the instrument. Finally, the device value/measured color values need
+ to be converted into an ICC profile.<br>
+ <br>
+ <h3><a name="PM1a"></a>Checking you can access your display<br>
+ </h3>
+ You might first want to check that you are accessing and can
+ calibrate your display. You can do this using the <a
+ href="dispwin.html">dispwin</a><span style="font-weight: bold;"></span>
+ tool<span style="font-weight: bold;">.</span> If you just run <span
+ style="font-weight: bold;">dispwin</span> it will create a test
+ window and run through a series of test colors before checking that
+ the VideoLUT can be accessed by the display. If you invoke the usage
+ for <span style="font-weight: bold;">dispwin</span> (by giving it
+ an unrecognized option, e.g. <span style="font-weight: bold;">-?</span>)
+ then it will show a list of available displays next to the <span
+ style="font-weight: bold;"><span style="font-weight: bold;">-d</span></span>
+ flag. Make sure that you are accessing the display you intend to
+ calibrate and profile, and that the VideoLUT is effective (the <span
+ style="font-weight: bold;">-r</span> flag can be used to just run
+ the VideoLUT test). You can also try clearing the VideoLUTs using
+ the <span style="font-weight: bold;">-c</span> flag, and loading a
+ deliberately strange looking calibration <span style="font-weight:
+ bold;">strange.cal</span> that is provided in the Argyll <span
+ style="font-weight: bold;">ref</span> directory.<br>
+ <br>
+ Note that calibrating and/or profiling <span style="font-weight:
+ bold;">remote</span> displays is possible using X11 or a web
+ browser (see <span style="font-weight: bold;">-d</span> option of
+ dispcal and dispread), or by using some external program to send
+ test colors to a display (see <span style="font-weight: bold;">-C</span>
+ and <span style="font-weight: bold;">-M</span> options of dispcal
and dispread), but you may want to refer to <a href="#PM7">Calibrating @@ -181,29 +181,27 @@ - - - - and profiling a display that doesn't have VideoLUT access</a>.<br> - <br> - <h3><a name="PM1b"></a>Adjusting and Calibrating Displays</h3> - Please read <a href="calvschar.html">What's the difference between - Calibration and Characterization ?</a> if you are unclear as to - the difference .<br> - <br> - The first step is to decide what the target should be for adjustment - and calibration. This boils down to three things: The desired - brightness, the desired white point, and the desired response curve. - The native brightness and white points of a display may be different - to the desired characteristics for some purposes. For instance, for - graphic arts use, it might be desirable to run with a warmer white - point of about 5000 degrees Kelvin, rather than the default display - white point of 6500 to 9000 Kelvin. Some LCD displays are too bright - to compare to printed material under available lighting, so it might - be desirable to reduce the maximum brightness.<br> - <br> - You can run <a href="dispcal.html#r">dispcal -r</a> to check on how - your display is currently set up. (you may have to run this as <span +
+ and profiling a display that doesn't have VideoLUT access</a>.<br>
+ <br>
+ <h3><a name="PM1b"></a>Adjusting and Calibrating Displays</h3>
+ Please read <a href="calvschar.html">What's the difference between
+ Calibration and Characterization ?</a> if you are unclear as to
+ the difference .<br>
+ <br>
+ The first step is to decide what the target should be for adjustment
+ and calibration. This boils down to three things: The desired
+ brightness, the desired white point, and the desired response curve.
+ The native brightness and white points of a display may be different
+ to the desired characteristics for some purposes. For instance, for
+ graphic arts use, it might be desirable to run with a warmer white
+ point of about 5000 degrees Kelvin, rather than the default display
+ white point of 6500 to 9000 Kelvin. Some LCD displays are too bright
+ to compare to printed material under available lighting, so it might
+ be desirable to reduce the maximum brightness.<br>
+ <br>
+ You can run <a href="dispcal.html#r">dispcal -r</a> to check on how
+ your display is currently set up. (you may have to run this as <span
style="text-decoration: underline; color: rgb(204, 51, 204);">dispcal -yl @@ -262,334 +260,332 @@ - - - - -r</span> for an LCD display, or <span style="text-decoration: - underline; color: rgb(204, 51, 204);">dispcal -yc -r</span> for a - CRT display with most of the colorimeter instruments. If so, this - will apply to all of the following examples.)<br> - <br> - Once this is done, <a href="dispcal.html">dispcal</a> can be run to - guide you through the display adjustments, and then calibrate it. By - default, the brightness and white point will be kept the same as the - devices natural brightness and white point. The default response - curve is a gamma of 2.4, except for Apple OS X systems prior to 10.6 - where a gamma of 1.8 is the default. 2.4 is close to that of - many monitors, and close to that of the sRGB colorspace. <br> - <br> - A typical calibration that leaves the brightness and white point - alone, might be:<br> - <br> - <a href="dispcal.html">dispcal</a> -v TargetA<br> - <br> - which will result in a "TargetA.cal" calibration file, that can then - be used during the profiling stage.<br> - <br> - If the absolutely native response of the display is desired during - profiling, then calibration should be skipped, and the linear.cal - file from the "ref" directory used instead as the argument to the -k - flag of <span style="font-weight: bold;">dispread</span>.<br> - <br> - <b>Dispcal</b> will display a test window in the middle of the - screen, and issue a series of instructions about placing the - instrument on the display. You may need to make sure that the - display cursor is not in the test window, and it may also be - necessary to disable any screensaver and powersavers before starting - the process, although both <span style="font-weight: bold;">dispcal</span> - and <span style="font-weight: bold;">dispread</span> will attempt - to do this for you. It's also highly desirable on CRT's, to clear - your screen of any white or bright background images or windows - (running your shell window with white text on a black background - helps a lot here.), or at least keep any bright areas away from the - test window, and be careful not to change anything on the display - while the readings are taken. Lots of bright images or windows can - affect the ability to measure the black point accurately, and - changing images on the display can cause inconsistency in the - readings, and leading to poor results.<span - style="font-weight: bold;"></span> LCD displays seem to be less - influenced by what else is on the screen.<br> - <br> - If <span style="font-weight: bold;">dispcal</span> is run without - arguments, it will provide a usage screen. The <span - style="font-weight: bold;">-c</span> parameter allows selecting a - communication port for an instrument, or selecting the instrument - you want to use, and the <a href="dispcal.html#d"><span - style="font-weight: bold;">-d</span></a> option allows selecting - a target display on a multi-display system. On some multi-monitor - systems, it may not be possible to independently calibrate and - profile each display if they appear as one single screen to the - operating system, or if it is not possible to set separate video - lookup tables for each display. You can change the position and size - of the test window using the <a href="dispcal.html#P"><span - style="font-weight: bold;">-P</span></a> parameter. You can - determine how best to arrange the test window, as well as whether - each display has separate video lookup capability, by experimenting - with the <a href="dispwin.html">dispwin</a> tool. <br> - <br> - For a more detailed discussion on interactively adjusting the - display controls using <span style="font-weight: bold;">dispcal</span>, - see <a href="dispcal.html#Adjustment">dispcal-adjustment</a>. Once - you have adjusted and calibrated your display, you can move on to - the next step.<br> - <br> - When you have calibrated and profiled your display, you can keep it - calibrated using the <a href="dispcal.html#u">dispcal -u</a> - option.<br> - <br> - <h4><a name="PM1c"></a>Adjusting, calibrating and profiling in one - step.</h4> - If a simple matrix/shaper display profile is all that is desired, <span - style="font-weight: bold;">dispcal</span> can be used to do this, - permitting display adjustment, calibration and profiling all in one - operation. This is done by using the <span style="font-weight: - bold;"><span style="font-weight: bold;">dispcal </span>-o</span> - flag:<br> - <br> - <a href="dispcal.html">dispcal</a> <a href="dispcal.html#v">-v</a> - <a href="dispcal.html#o">-o</a> <a href="dispcal.html#p1">TargetA</a><br> - <br> - This will create both a TargetA.cal file, but also a TargetA.icm - file. See <a href="dispcal.html#o">-o</a> and <a - href="dispcal.html#O">-O</a> for other variations.<br> - <br> - For more flexibility in creating a display profile, the separate - steps of creating characterization test values using <span - style="font-weight: bold;">targen</span>, reading them from the - display using <span style="font-weight: bold;">dispread</span>, and - then creating a profile using <span style="font-weight: bold;">colprof</span> - are used. The following steps illustrate this:<br> - <h4><a name="PM2"></a>Profiling in several steps: Creating display - test values</h4> - If the <span style="font-weight: bold;">dispcal</span> has not been - used to create a display profile at the same time as adjustment and - calibration, then it can be used to create a suitable set of - calibration curves as the first step, or the calibration step can be - omitted, and the display cansimply be profiled.<br> - <br> - The first step in profiling any output device, is to create a set of - device colorspace test values. The important parameters needed are: - <br> - <ul> - <li>What colorspace does the device use ?</li> - <li>How many test patches do I want to use ?</li> - <li>What information do I already have about how the device - behaves ?</li> - </ul> - For a display device, the colorspace will be RGB. The number - of test patches will depend somewhat on what quality profile you - want to make, what type of profile you want to make, and how long - you are prepared to wait when testing the display.<br> - At a minimum, a few hundred values are needed. A matrix/shaper type - of profile can get by with fewer test values, while a LUT based - profile will give better results if more test values are used. A - typical number might be 200-600 or so values, while 1000-2000 is not - an unreasonable number for a high quality characterization of a - display.<br> - <br> - To assist the choice of test patch values, it can help to have a - rough idea of how the device behaves. This could be in the form of - an ICC profile of a similar device, or a lower quality, or previous - profile for that particular device. If one were going to make a very - high quality LUT based profile, then it might be worthwhile to make - up a smaller, preliminary shaper/matrix profile using a few hundred - test points, before embarking on testing the device with several - thousand.<br> - <br> - Lets say that we ultimately want to make a profile for the device - "DisplayA", the simplest approach is to make a set of test values - that is independent of the characteristics of the particular device:<br> - <br> - <a href="targen.html">targen</a> <a href="targen.html#v">-v</a> - <a href="targen.html#d">-d3</a> <a href="targen.html#f">-f500</a> - <a href="targen.html#p1">DisplayA</a><br> - <br> - If there is a preliminary or previous profile called "OldDisplay" - available, and we want to try creating a "pre-conditioned" set of - test values that will more efficiently sample the device response, - then the following would achieve this:<br> - <u><br> - </u><a href="targen.html"> targen</a> <a href="targen.html#v">-v</a> - <a href="targen.html#d">-d3</a> <a href="targen.html#f">-f500</a> - <a href="targen.html#c">-cOldDisplay.icm</a> <a - href="targen.html#p1">DisplayA</a><br> - <br> - The output of <b>targen</b> will be the file DisplayA.ti1, - containing the device space test values, as well as expected CIE - values used for chart recognition purposes.<br> - <br> - <h4><a name="PM3"></a>Profiling in several steps: Taking readings - from a display</h4> - First it is necessary to connect your measurement instrument to your - computer, and check which communication port it is connected to. In - the following example, it is assumed that the instrument is - connected to the default port 1, which is either the first USB - instrument found, or serial port found. Invoking dispread so as to - display the usage information (by using a flag -? or --) will list - the identified serial and USB ports, and their labels.<br> - <br> - <a href="dispread.html">dispread</a> <a href="dispread.html#v">-v</a> - <a href="dispread.html#p1">DisplayA</a><br> - <br> - If we created a calibration for the display using <a - href="dispcal.html">dispcal</a>, then we will want to use this - when we take the display readings (e.g. TargetA.cal from the - calibration example)..<br> - <br> - <a href="dispread.html">dispread</a> <a href="dispread.html#v">-v</a> - <a href="dispread.html#k">-k TargetA.cal</a> <a - href="dispread.html#p1">DisplayA</a><br> - <br> - <b>dispread</b> will display a test window in the middle of the - screen, and issue a series of instructions about placing the - instrument on the display. You may need to make sure that the - display cursor is not in the test window, and it may also be - necessary to disable any screensaver before starting the process. - Exactly the same facilities are provided to select alternate - displays using the <span style="font-weight: bold;">-d</span> - parameter, and an alternate location and size for the test window - using the <span style="font-weight: bold;">-P</span> parameter as - with <span style="font-weight: bold;">dispcal</span>.<br> - <h4><a name="PM4"></a>Profiling in several steps: Creating a display - profile</h4> - There are two basic choices of profile type for a display, a - shaper/matrix profile, or a LUT based profile. They have different - tradeoffs. A shaper/matrix profile will work well on a well behaved - display, that is one that behaves in an additive color manner, will - give very smooth looking results, and needs fewer test points to - create. A LUT based profile on the other hand, will model any - display behaviour more accurately, and can accommodate gamut mapping - and different intent tables. Often it can show some unevenness and - contouring in the results though.<br> - <br> - To create a matrix/shaper profile, the following suffices:<br> - <br> - <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a> - <a href="colprof.html#E">-D"Display A"</a> <a href="colprof.html#q">-qm</a> - <a href="colprof.html#a">-as</a> <a href="colprof.html#p1">DisplayA</a><br> - <br> - For a LUT based profile, where gamut mapping is desired, then a - source profile will need to be provided to define the source gamut. - For instance, if the display profile was likely to be linked to a - CMYK printing source profile, say "swop.icm" or "fogra39l.icm", then - the following would suffice:<br> - <br> - <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a> - <a href="colprof.html#E">-D"Display A"</a> <a href="colprof.html#q">-qm</a> - <a href="colprof.html#S">-S</a><a href="colprof.html#S"> - fogra39l.icm</a> <a href="colprof.html#c">-cpp</a> <a - href="colprof.html#d">-dmt</a> <a href="colprof.html#p1">DisplayA</a><br> - <br> - Make sure you check the delta E report at the end of the profile - creation, to see if the sample data and profile is behaving - reasonably.<br> - If a calibration file was used with <a href="dispread.html">dispread</a>, - then it will be converted to a vcgt tag in the profile, so that the - operating system or other system color tools load the lookup curves - into the display hardware, when the profile is used.<br> - <h4><a name="PM5"></a>Installing a display profile</h4> - <a href="dispwin.html">dispwin</a> provides a convenient way of - installing a profile as the default system profile for the chosen - display:<br> - <br> - <a href="dispwin.html">dispwin</a> <a href="dispwin.html#I">-I</a> - <a href="dispwin.html#p1">DisplayA.icm</a><br> - <br> - This also sets the display to the calibration contained in the - profile. If you want to try out a calibration before installing the - profile, using dispwin without the <span style="font-weight: bold;">-I</span> - option will load a calibration (ICC profile or .cal file) into the - current display.<br> - <br> - Some systems will automatically set the display to the calibration - contained in the installed profile (ie. OS X), while on other - systems (ie. MSWindows and Linux/X11) it is necessary to use some - tool to do this. On MSWindows XP you could install the - optional <span style="font-weight: bold;">Microsoft Color Control Panel Applet for Windows XP</span> - available for download from Microsoft to do this, but <span - style="font-weight: bold;">NOTE</span> however that it seems to - have a <span style="font-weight: bold;">bug</span>, in that it - sometimes associates the profiles with the <span - style="font-weight: bold;">wrong monitor</span> entry. Other - display calibration tools will often install a similar tool, so - beware of there being multiple, competing programs. [ Commonly these - will be in your Start->Programs->Startup folder. ]<br> - On Microsoft Vista, you need to use dispwin -L or some other tool to - load the installed profiles calibration at startup.<br> - <br> - To use dispwin to load the installed profiles calibration to the - display, use<br> - <br> - <a href="dispwin.html">dispwin</a> <a href="dispwin.html#L">-L</a><br> - <br> - As per usual, you can select the appropriate display using the <a - href="dispwin.html#d">-d</a> flag.<br> - <br> - This can be automated on MSWindows and X11/Linux by adding this - command to an appropriate startup script.<br> - More system specific details, including how to create such startup - scripts are <a href="dispprofloc.html">here</a>. <br> - <br> - If you are using Microsoft <span style="font-weight: bold;">Vista</span>, - there is a known <span style="font-weight: bold;">bug</span> in - Vista that resets the calibration every time a fade-in effect is - executed, which happens if you lock and unlock the computer, resume - from sleep or hibernate, or User Access Control is activated. Using - <a href="dispwin.html">dispwin</a> <a href="dispwin.html#L">-L</a> - may not restore the calibration, because Vista filters out setting - (what it thinks) is a calibration that is already loaded. Use <a - href="dispwin.html">dispwin</a> <a href="dispwin.html#c">-c</a> <a - href="dispwin.html#L">-L</a><span style="font-family: monospace;"></span> - as a workaround, as this will first clear the calibration, then - re-load the current calibration.<br> - <br> - On X11/Linux systems, you could try adding <a href="dispwin.html">dispwin</a> - <a href="dispwin.html#L">-L</a> to your <span style="font-weight: - bold;">~/.config/autostart</span> file, so that your window - manager automatically sets calibration when it starts. If you are - running XRandR 1.2, you might consider running the experimental <a - href="dispwin.html#D">dispwin -E</a> in the background, as in its - "daemon" mode it will update the profile and calibration in response - to any changes in the the connected display.<br> - <br> - <h4><a name="PM6"></a>Expert tips when measuring displays:<br> - </h4> - Sometimes it can be difficult to get good quality, consistent and - visually relevant readings from displays, due to various practical - considerations with regard to instruments and the displays - themselves. Argyll's tools have some extra options that may assist - in overcoming these problems.<br> - <br> - If you are using an Eye-One Pro or ColorMunki spectrometer, then you - may wish to use the <a href="dispcal.html#H">high resolution - spectral mode</a> (<span style="font-weight: bold;">-H</span>). - This may be better at capturing the often narrow wavelength peaks - that are typical of display primary colors.<br> - <br> - All instruments depend on silicon sensors, and such sensors generate - a temperature dependant level of noise ("dark noise") that is - factored out of the measurements by a dark or black instrument - calibration. The spectrometers in particular need this calibration - before commencing each set of measurements. Often an instrument will - warm up as it sits on a display, and this warming up can cause the - dark noise to increase, leading to inaccuracies in dark patch - measurements. The longer the measurement takes, the worse this - problem is likely to be. One way of addressing this is to - "acclimatise" the instrument before commencing measurements by - placing it on the screen in a powered up state, and leaving it for - some time. (Some people leave it for up to an hour to acclimatise.). - Another approach is to try and <a href="dispcal.html#I">compensate - for dark calibration changes</a> (<span style="font-weight: bold;">-Ib</span>) - by doing on the fly calibrations during the measurements, based on - the assumption that the black level of the display itself won't - change significantly. <br> - <br> - Some displays take a long time to settle down and stabilise. The is - often the case with LCD (Liquid Crystal) displays that use - fluorescent back lights, and these sorts of displays can change in - brightness significantly with changes in temperature. One way of - addressing this is to make sure that the display is given adequate - time to warm up before measurements. Another approach is to try and +
+ -r</span> for an LCD display, or <span style="text-decoration:
+ underline; color: rgb(204, 51, 204);">dispcal -yc -r</span> for a
+ CRT display with most of the colorimeter instruments. If so, this
+ will apply to all of the following examples.)<br>
+ <br>
+ Once this is done, <a href="dispcal.html">dispcal</a> can be run to
+ guide you through the display adjustments, and then calibrate it. By
+ default, the brightness and white point will be kept the same as the
+ devices natural brightness and white point. The default response
+ curve is a gamma of 2.4, except for Apple OS X systems prior to 10.6
+ where a gamma of 1.8 is the default. 2.4 is close to that of
+ many monitors, and close to that of the sRGB colorspace. <br>
+ <br>
+ A typical calibration that leaves the brightness and white point
+ alone, might be:<br>
+ <br>
+ <a href="dispcal.html">dispcal</a> -v TargetA<br>
+ <br>
+ which will result in a "TargetA.cal" calibration file, that can then
+ be used during the profiling stage.<br>
+ <br>
+ If the absolutely native response of the display is desired during
+ profiling, then calibration should be skipped, and the linear.cal
+ file from the "ref" directory used instead as the argument to the -k
+ flag of <span style="font-weight: bold;">dispread</span>.<br>
+ <br>
+ <b>Dispcal</b> will display a test window in the middle of the
+ screen, and issue a series of instructions about placing the
+ instrument on the display. You may need to make sure that the
+ display cursor is not in the test window, and it may also be
+ necessary to disable any screensaver and powersavers before starting
+ the process, although both <span style="font-weight: bold;">dispcal</span>
+ and <span style="font-weight: bold;">dispread</span> will attempt
+ to do this for you. It's also highly desirable on CRT's, to clear
+ your screen of any white or bright background images or windows
+ (running your shell window with white text on a black background
+ helps a lot here.), or at least keep any bright areas away from the
+ test window, and be careful not to change anything on the display
+ while the readings are taken. Lots of bright images or windows can
+ affect the ability to measure the black point accurately, and
+ changing images on the display can cause inconsistency in the
+ readings, and leading to poor results.<span
+ style="font-weight: bold;"></span> LCD displays seem to be less
+ influenced by what else is on the screen.<br>
+ <br>
+ If <span style="font-weight: bold;">dispcal</span> is run without
+ arguments, it will provide a usage screen. The <span
+ style="font-weight: bold;">-c</span> parameter allows selecting a
+ communication port for an instrument, or selecting the instrument
+ you want to use, and the <a href="dispcal.html#d"><span
+ style="font-weight: bold;">-d</span></a> option allows selecting
+ a target display on a multi-display system. On some multi-monitor
+ systems, it may not be possible to independently calibrate and
+ profile each display if they appear as one single screen to the
+ operating system, or if it is not possible to set separate video
+ lookup tables for each display. You can change the position and size
+ of the test window using the <a href="dispcal.html#P"><span
+ style="font-weight: bold;">-P</span></a> parameter. You can
+ determine how best to arrange the test window, as well as whether
+ each display has separate video lookup capability, by experimenting
+ with the <a href="dispwin.html">dispwin</a> tool. <br>
+ <br>
+ For a more detailed discussion on interactively adjusting the
+ display controls using <span style="font-weight: bold;">dispcal</span>,
+ see <a href="dispcal.html#Adjustment">dispcal-adjustment</a>. Once
+ you have adjusted and calibrated your display, you can move on to
+ the next step.<br>
+ <br>
+ When you have calibrated and profiled your display, you can keep it
+ calibrated using the <a href="dispcal.html#u">dispcal -u</a>
+ option.<br>
+ <br>
+ <h4><a name="PM1c"></a>Adjusting, calibrating and profiling in one
+ step.</h4>
+ If a simple matrix/shaper display profile is all that is desired, <span
+ style="font-weight: bold;">dispcal</span> can be used to do this,
+ permitting display adjustment, calibration and profiling all in one
+ operation. This is done by using the <span style="font-weight:
+ bold;"><span style="font-weight: bold;">dispcal </span>-o</span>
+ flag:<br>
+ <br>
+ <a href="dispcal.html">dispcal</a> <a href="dispcal.html#v">-v</a>
+ <a href="dispcal.html#o">-o</a> <a href="dispcal.html#p1">TargetA</a><br>
+ <br>
+ This will create both a TargetA.cal file, but also a TargetA.icm
+ file. See <a href="dispcal.html#o">-o</a> and <a
+ href="dispcal.html#O">-O</a> for other variations.<br>
+ <br>
+ For more flexibility in creating a display profile, the separate
+ steps of creating characterization test values using <span
+ style="font-weight: bold;">targen</span>, reading them from the
+ display using <span style="font-weight: bold;">dispread</span>, and
+ then creating a profile using <span style="font-weight: bold;">colprof</span>
+ are used. The following steps illustrate this:<br>
+ <h4><a name="PM2"></a>Profiling in several steps: Creating display
+ test values</h4>
+ If the <span style="font-weight: bold;">dispcal</span> has not been
+ used to create a display profile at the same time as adjustment and
+ calibration, then it can be used to create a suitable set of
+ calibration curves as the first step, or the calibration step can be
+ omitted, and the display cansimply be profiled.<br>
+ <br>
+ The first step in profiling any output device, is to create a set of
+ device colorspace test values. The important parameters needed are:
+ <br>
+ <ul>
+ <li>What colorspace does the device use ?</li>
+ <li>How many test patches do I want to use ?</li>
+ <li>What information do I already have about how the device
+ behaves ?</li>
+ </ul>
+ For a display device, the colorspace will be RGB. The number
+ of test patches will depend somewhat on what quality profile you
+ want to make, what type of profile you want to make, and how long
+ you are prepared to wait when testing the display.<br>
+ At a minimum, a few hundred values are needed. A matrix/shaper type
+ of profile can get by with fewer test values, while a LUT based
+ profile will give better results if more test values are used. A
+ typical number might be 200-600 or so values, while 1000-2000 is not
+ an unreasonable number for a high quality characterization of a
+ display.<br>
+ <br>
+ To assist the choice of test patch values, it can help to have a
+ rough idea of how the device behaves. This could be in the form of
+ an ICC profile of a similar device, or a lower quality, or previous
+ profile for that particular device. If one were going to make a very
+ high quality LUT based profile, then it might be worthwhile to make
+ up a smaller, preliminary shaper/matrix profile using a few hundred
+ test points, before embarking on testing the device with several
+ thousand.<br>
+ <br>
+ Lets say that we ultimately want to make a profile for the device
+ "DisplayA", the simplest approach is to make a set of test values
+ that is independent of the characteristics of the particular device:<br>
+ <br>
+ <a href="targen.html">targen</a> <a href="targen.html#v">-v</a>
+ <a href="targen.html#d">-d3</a> <a href="targen.html#f">-f500</a>
+ <a href="targen.html#p1">DisplayA</a><br>
+ <br>
+ If there is a preliminary or previous profile called "OldDisplay"
+ available, and we want to try creating a "pre-conditioned" set of
+ test values that will more efficiently sample the device response,
+ then the following would achieve this:<br>
+ <u><br>
+ </u><a href="targen.html"> targen</a> <a href="targen.html#v">-v</a>
+ <a href="targen.html#d">-d3</a> <a href="targen.html#f">-f500</a>
+ <a href="targen.html#c">-cOldDisplay.icm</a> <a
+ href="targen.html#p1">DisplayA</a><br>
+ <br>
+ The output of <b>targen</b> will be the file DisplayA.ti1,
+ containing the device space test values, as well as expected CIE
+ values used for chart recognition purposes.<br>
+ <br>
+ <h4><a name="PM3"></a>Profiling in several steps: Taking readings
+ from a display</h4>
+ First it is necessary to connect your measurement instrument to your
+ computer, and check which communication port it is connected to. In
+ the following example, it is assumed that the instrument is
+ connected to the default port 1, which is either the first USB
+ instrument found, or serial port found. Invoking dispread so as to
+ display the usage information (by using a flag -? or --) will list
+ the identified serial and USB ports, and their labels.<br>
+ <br>
+ <a href="dispread.html">dispread</a> <a href="dispread.html#v">-v</a>
+ <a href="dispread.html#p1">DisplayA</a><br>
+ <br>
+ If we created a calibration for the display using <a
+ href="dispcal.html">dispcal</a>, then we will want to use this
+ when we take the display readings (e.g. TargetA.cal from the
+ calibration example)..<br>
+ <br>
+ <a href="dispread.html">dispread</a> <a href="dispread.html#v">-v</a>
+ <a href="dispread.html#k">-k TargetA.cal</a> <a
+ href="dispread.html#p1">DisplayA</a><br>
+ <br>
+ <b>dispread</b> will display a test window in the middle of the
+ screen, and issue a series of instructions about placing the
+ instrument on the display. You may need to make sure that the
+ display cursor is not in the test window, and it may also be
+ necessary to disable any screensaver before starting the process.
+ Exactly the same facilities are provided to select alternate
+ displays using the <span style="font-weight: bold;">-d</span>
+ parameter, and an alternate location and size for the test window
+ using the <span style="font-weight: bold;">-P</span> parameter as
+ with <span style="font-weight: bold;">dispcal</span>.<br>
+ <h4><a name="PM4"></a>Profiling in several steps: Creating a display
+ profile</h4>
+ There are two basic choices of profile type for a display, a
+ shaper/matrix profile, or a LUT based profile. They have different
+ tradeoffs. A shaper/matrix profile will work well on a well behaved
+ display, that is one that behaves in an additive color manner, will
+ give very smooth looking results, and needs fewer test points to
+ create. A LUT based profile on the other hand, will model any
+ display behaviour more accurately, and can accommodate gamut mapping
+ and different intent tables. Often it can show some unevenness and
+ contouring in the results though.<br>
+ <br>
+ To create a matrix/shaper profile, the following suffices:<br>
+ <br>
+ <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a>
+ <a href="colprof.html#E">-D"Display A"</a> <a href="colprof.html#q">-qm</a>
+ <a href="colprof.html#a">-as</a> <a href="colprof.html#p1">DisplayA</a><br>
+ <br>
+ For a LUT based profile, where gamut mapping is desired, then a
+ source profile will need to be provided to define the source gamut.
+ For instance, if the display profile was likely to be linked to a
+ CMYK printing source profile, say "swop.icm" or "fogra39l.icm", then
+ the following would suffice:<br>
+ <br>
+ <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a>
+ <a href="colprof.html#E">-D"Display A"</a> <a href="colprof.html#q">-qm</a>
+ <a href="colprof.html#S">-S</a><a href="colprof.html#S">
+ fogra39l.icm</a> <a href="colprof.html#c">-cpp</a> <a
+ href="colprof.html#d">-dmt</a> <a href="colprof.html#p1">DisplayA</a><br>
+ <br>
+ Make sure you check the delta E report at the end of the profile
+ creation, to see if the sample data and profile is behaving
+ reasonably.<br>
+ If a calibration file was used with <a href="dispread.html">dispread</a>,
+ then it will be converted to a vcgt tag in the profile, so that the
+ operating system or other system color tools load the lookup curves
+ into the display hardware, when the profile is used.<br>
+ <h4><a name="PM5"></a>Installing a display profile</h4>
+ <a href="dispwin.html">dispwin</a> provides a convenient way of
+ installing a profile as the default system profile for the chosen
+ display:<br>
+ <br>
+ <a href="dispwin.html">dispwin</a> <a href="dispwin.html#I">-I</a>
+ <a href="dispwin.html#p1">DisplayA.icm</a><br>
+ <br>
+ This also sets the display to the calibration contained in the
+ profile. If you want to try out a calibration before installing the
+ profile, using dispwin without the <span style="font-weight: bold;">-I</span>
+ option will load a calibration (ICC profile or .cal file) into the
+ current display.<br>
+ <br>
+ Some systems will automatically set the display to the calibration
+ contained in the installed profile (ie. OS X), while on other
+ systems (ie. MSWindows and Linux/X11) it is necessary to use some
+ tool to do this. On MSWindows XP you could install the
+ optional <span style="font-weight: bold;">Microsoft Color Control Panel Applet for Windows XP</span>
+ available for download from Microsoft to do this, but <span
+ style="font-weight: bold;">NOTE</span> however that it seems to
+ have a <span style="font-weight: bold;">bug</span>, in that it
+ sometimes associates the profiles with the <span
+ style="font-weight: bold;">wrong monitor</span> entry. Other
+ display calibration tools will often install a similar tool, so
+ beware of there being multiple, competing programs. [ Commonly these
+ will be in your Start->Programs->Startup folder. ]<br>
+ On Microsoft Vista, you need to use dispwin -L or some other tool to
+ load the installed profiles calibration at startup.<br>
+ <br>
+ To use dispwin to load the installed profiles calibration to the
+ display, use<br>
+ <br>
+ <a href="dispwin.html">dispwin</a> <a href="dispwin.html#L">-L</a><br>
+ <br>
+ As per usual, you can select the appropriate display using the <a
+ href="dispwin.html#d">-d</a> flag.<br>
+ <br>
+ This can be automated on MSWindows and X11/Linux by adding this
+ command to an appropriate startup script.<br>
+ More system specific details, including how to create such startup
+ scripts are <a href="dispprofloc.html">here</a>. <br>
+ <br>
+ If you are using Microsoft <span style="font-weight: bold;">Vista</span>,
+ there is a known <span style="font-weight: bold;">bug</span> in
+ Vista that resets the calibration every time a fade-in effect is
+ executed, which happens if you lock and unlock the computer, resume
+ from sleep or hibernate, or User Access Control is activated. Using
+ <a href="dispwin.html">dispwin</a> <a href="dispwin.html#L">-L</a>
+ may not restore the calibration, because Vista filters out setting
+ (what it thinks) is a calibration that is already loaded. Use <a
+ href="dispwin.html">dispwin</a> <a href="dispwin.html#c">-c</a> <a
+ href="dispwin.html#L">-L</a><span style="font-family: monospace;"></span>
+ as a workaround, as this will first clear the calibration, then
+ re-load the current calibration.<br>
+ <br>
+ On X11/Linux systems, you could try adding <a href="dispwin.html">dispwin</a>
+ <a href="dispwin.html#L">-L</a> to your <span style="font-weight:
+ bold;">~/.config/autostart</span> file, so that your window
+ manager automatically sets calibration when it starts. If you are
+ running XRandR 1.2, you might consider running the experimental <a
+ href="dispwin.html#D">dispwin -E</a> in the background, as in its
+ "daemon" mode it will update the profile and calibration in response
+ to any changes in the the connected display.<br>
+ <br>
+ <h4><a name="PM6"></a>Expert tips when measuring displays:<br>
+ </h4>
+ Sometimes it can be difficult to get good quality, consistent and
+ visually relevant readings from displays, due to various practical
+ considerations with regard to instruments and the displays
+ themselves. Argyll's tools have some extra options that may assist
+ in overcoming these problems.<br>
+ <br>
+ If you are using an Eye-One Pro or ColorMunki spectrometer, then you
+ may wish to use the <a href="dispcal.html#H">high resolution
+ spectral mode</a> (<span style="font-weight: bold;">-H</span>).
+ This may be better at capturing the often narrow wavelength peaks
+ that are typical of display primary colors.<br>
+ <br>
+ All instruments depend on silicon sensors, and such sensors generate
+ a temperature dependant level of noise ("dark noise") that is
+ factored out of the measurements by a dark or black instrument
+ calibration. The spectrometers in particular need this calibration
+ before commencing each set of measurements. Often an instrument will
+ warm up as it sits on a display, and this warming up can cause the
+ dark noise to increase, leading to inaccuracies in dark patch
+ measurements. The longer the measurement takes, the worse this
+ problem is likely to be. One way of addressing this is to
+ "acclimatise" the instrument before commencing measurements by
+ placing it on the screen in a powered up state, and leaving it for
+ some time. (Some people leave it for up to an hour to acclimatise.).
+ Another approach is to try and <a href="dispcal.html#I">compensate
+ for dark calibration changes</a> (<span style="font-weight: bold;">-Ib</span>)
+ by doing on the fly calibrations during the measurements, based on
+ the assumption that the black level of the display itself won't
+ change significantly. <br>
+ <br>
+ Some displays take a long time to settle down and stabilise. The is
+ often the case with LCD (Liquid Crystal) displays that use
+ fluorescent back lights, and these sorts of displays can change in
+ brightness significantly with changes in temperature. One way of
+ addressing this is to make sure that the display is given adequate
+ time to warm up before measurements. Another approach is to try and
<a href="dispcal.html#I">compensate for display white level</a> @@ -647,23 +643,21 @@ - - - - (<span style="font-weight: bold;">-Iw</span>) changes by doing on - the fly calibrations during the measurements. Instrument black level - drift and display white level drift can be combined (<span - style="font-weight: bold;">-Ibw</span>).<br> - <br> - Colorimeter instruments make use of physical color filters that - approximate the standard observer spectral sensitivity curves. - Because these filters are not perfectly accurate, the manufacturer - calibrates the instrument for typical displays, which is why you - have to make a selection between CRT (Cathode Ray Tube) and LCD - (Liquid Crystal Display) modes. If you are measuring a display that - has primary colorants that differ significantly from those typical - displays, (ie. you have a Wide Gamut Display), then you may - get disappointing results with a Colorimeter. One way of addressing +
+ (<span style="font-weight: bold;">-Iw</span>) changes by doing on
+ the fly calibrations during the measurements. Instrument black level
+ drift and display white level drift can be combined (<span
+ style="font-weight: bold;">-Ibw</span>).<br>
+ <br>
+ Colorimeter instruments make use of physical color filters that
+ approximate the standard observer spectral sensitivity curves.
+ Because these filters are not perfectly accurate, the manufacturer
+ calibrates the instrument for typical displays, which is why you
+ have to make a selection between CRT (Cathode Ray Tube) and LCD
+ (Liquid Crystal Display) modes. If you are measuring a display that
+ has primary colorants that differ significantly from those typical
+ displays, (ie. you have a Wide Gamut Display), then you may
+ get disappointing results with a Colorimeter. One way of addressing
this problem is to use a <a href="File_Formats.html#.ccmx">Colorimeter @@ -720,120 +714,118 @@ - - - - Correction Matrix</a>. These are specific to a particular - Colorimeter and Display make and model combination, although a - matrix for a different but similar type of display may give better - results than none at all. A list of contributed <span - style="font-weight: bold;">ccmx</span> files is <a - href="ccmxs.html">here</a>.<br> - <br> - <h4><a name="PM7"></a>Calibrating and profiling a display that - doesn't have VideoLUT access.</h4> - <p>In some situation there is no access to a displays VideoLUT - hardware, and this hardware is what is usually used to implement - display calibration. This could be because the display is being - accessed via a web server, or because the driver or windowing - system doesn't support VideoLUT access.<br> - </p> - <p>There are two basic options in this situation:<br> - </p> - <p> 1) Don't attempt to calibrate, just profile the display.<br> - 2) Calibrate, but incorporate the calibration in some other - way in the workflow.<br> - </p> - <p>The first case requires nothing special - just skip calibration - (see the previous section <a href="#PM7">Profiling in several - steps: Creating display test values</a>).</p> - <p> In the second case, there are three choices:<br> - </p> - <p> 2a) Use dispcal to create a calibration and a quick profile - that incorporates the calibration into the profile.<br> - 2b) Use dispcal to create the calibration, then dispread and - colprof to create a profile, and then incorporate the calibration - into the profile using applycal.<br> - 2c) Use dispcal to create the calibration, then dispread and - colprof to create a profile, and then apply the calibration after - the profile in a cctiff workflow.<br> - </p> - <p>The first case requires nothing special, use dispcal in a normal - fashioned with the <span style="font-weight: bold;">-o</span> - option to generate a quick profile.The profile created will <span - style="text-decoration: underline;">not</span> contain a 'vcgt' - tag, but instead will have the calibration curves incorporated - into the profile itself. If calibration parameters are chosen that - change the displays white point or brightness, then this will - result in a slightly unusual profile that has a white point that - does not correspond with device R=G=B=1.0. Some systems may not - cope properly with this type of profile, and a general shift in - white point through such a profile can create an odd looking - display if it is applied to images but not to other elements on - the display say as GUI decoration elements or other application - windows.<br> - </p> - <p>In the second case, the calibration file created using dispcal - should be provided to dispread using the <span - style="font-weight: bold;">-K</span> flag:<br> - </p> - <p><a href="dispread.html">dispread</a> <a href="dispread.html#v">-v</a> - <a href="dispread.html#K">-K TargetA.cal</a> <a - href="dispread.html#p1">DisplayA</a></p> - <p><span style="font-weight: bold;"></span>Create the profile as - usual using colprof. but note that colprof will ignore the - calibration, and that no 'vcgt' tag will be added to the profile.<br> - You can then use <a href="applycal.html">applycal </a>to combine - the calibration into the profile. Note that the resulting profile - will be slightly unusual, since the profile is not made completely - consistent with the effects of the calibration, and the device - R=G=B=1.0 probably not longer corresponds with the PCS white or - the white point.<br> - </p> - In the third case, the same procedure as above is used to create a - profile, but the calibration is applied in a raster transformation - workflow explicitly, e.g.:<br> - <br> - <a href="cctiff.html">cctiff</a> <a - href="cctiff.html#p1">SourceProfile.icm</a> <a - href="cctiff.html#p1">DisplayA.icm</a> <a href="cctiff.html#p2">DisplayA.cal</a> - <a href="cctiff.html#p3">infile.tif</a> <a href="cctiff.html#p4">outfile.tif</a><br> - or<br> - <a href="cctiff.html">cctiff</a> <a - href="cctiff.html#p1">SourceProfile.icm</a> <a - href="cctiff.html#p1">DisplayA.icm</a> <a href="cctiff.html#p2">DisplayA.cal</a> - <a href="cctiff.html#p3">infile.jpg</a> <a href="cctiff.html#p4">outfile.jpg</a><br> - <span style="font-weight: bold;"></span><br> - <hr size="2" width="100%"> - <h3><a name="PS1"></a>Profiling Scanners and other input devices - such as cameras<br> - </h3> - Because a scanner or camera is an input device, it is necessary to - go about profiling it in quite a different way to an output device. - To profile it, a test chart is needed to exercise the input device - response, to which the CIE values for each test patch is known. - Generally standard reflection or transparency test charts are used - for this purpose.<br> - <h4><a name="PS2"></a>Types of test charts</h4> - The most common and popular test chart for scanner profiling is the - IT8.7/2 chart. This is a standard format chart generally reproduced - on photographic film, containing about 264 test patches.<br> - An accessible and affordable source of such targets is Wolf Faust a - <a href="http://www.targets.coloraid.de/">www.coloraid.de</a>.<br> - Another source is LaserSoft <a - href="http://www.silverfast.com/show/it8/en.html">www.silverfast.com.</a><br> - The Kodak Q-60 Color Input Target is also a typical example:<br> - <br> - <img src="Q60.jpg" alt="Kodak Q60 chart image" width="200" - height="141"> <br> - <br> - A very simple chart that is widely available is the Macbeth - ColorChecker chart, although it contains only 24 patches and - therefore is probably not ideal for creating profiles:<br> - <img alt="ColorChecker 24 patch" src="colorchecker.jpg" - style="width: 112px; height: 78px;"><br> - <br> - Other popular charts are the X-Rite/GretagMacbeth ColorChecker DC +
+ Correction Matrix</a>. These are specific to a particular
+ Colorimeter and Display make and model combination, although a
+ matrix for a different but similar type of display may give better
+ results than none at all. A list of contributed <span
+ style="font-weight: bold;">ccmx</span> files is <a
+ href="ccmxs.html">here</a>.<br>
+ <br>
+ <h4><a name="PM7"></a>Calibrating and profiling a display that
+ doesn't have VideoLUT access.</h4>
+ <p>In some situation there is no access to a displays VideoLUT
+ hardware, and this hardware is what is usually used to implement
+ display calibration. This could be because the display is being
+ accessed via a web server, or because the driver or windowing
+ system doesn't support VideoLUT access.<br>
+ </p>
+ <p>There are two basic options in this situation:<br>
+ </p>
+ <p> 1) Don't attempt to calibrate, just profile the display.<br>
+ 2) Calibrate, but incorporate the calibration in some other
+ way in the workflow.<br>
+ </p>
+ <p>The first case requires nothing special - just skip calibration
+ (see the previous section <a href="#PM7">Profiling in several
+ steps: Creating display test values</a>).</p>
+ <p> In the second case, there are three choices:<br>
+ </p>
+ <p> 2a) Use dispcal to create a calibration and a quick profile
+ that incorporates the calibration into the profile.<br>
+ 2b) Use dispcal to create the calibration, then dispread and
+ colprof to create a profile, and then incorporate the calibration
+ into the profile using applycal.<br>
+ 2c) Use dispcal to create the calibration, then dispread and
+ colprof to create a profile, and then apply the calibration after
+ the profile in a cctiff workflow.<br>
+ </p>
+ <p>The first case requires nothing special, use dispcal in a normal
+ fashioned with the <span style="font-weight: bold;">-o</span>
+ option to generate a quick profile.The profile created will <span
+ style="text-decoration: underline;">not</span> contain a 'vcgt'
+ tag, but instead will have the calibration curves incorporated
+ into the profile itself. If calibration parameters are chosen that
+ change the displays white point or brightness, then this will
+ result in a slightly unusual profile that has a white point that
+ does not correspond with device R=G=B=1.0. Some systems may not
+ cope properly with this type of profile, and a general shift in
+ white point through such a profile can create an odd looking
+ display if it is applied to images but not to other elements on
+ the display say as GUI decoration elements or other application
+ windows.<br>
+ </p>
+ <p>In the second case, the calibration file created using dispcal
+ should be provided to dispread using the <span
+ style="font-weight: bold;">-K</span> flag:<br>
+ </p>
+ <p><a href="dispread.html">dispread</a> <a href="dispread.html#v">-v</a>
+ <a href="dispread.html#K">-K TargetA.cal</a> <a
+ href="dispread.html#p1">DisplayA</a></p>
+ <p><span style="font-weight: bold;"></span>Create the profile as
+ usual using colprof. but note that colprof will ignore the
+ calibration, and that no 'vcgt' tag will be added to the profile.<br>
+ You can then use <a href="applycal.html">applycal </a>to combine
+ the calibration into the profile. Note that the resulting profile
+ will be slightly unusual, since the profile is not made completely
+ consistent with the effects of the calibration, and the device
+ R=G=B=1.0 probably not longer corresponds with the PCS white or
+ the white point.<br>
+ </p>
+ In the third case, the same procedure as above is used to create a
+ profile, but the calibration is applied in a raster transformation
+ workflow explicitly, e.g.:<br>
+ <br>
+ <a href="cctiff.html">cctiff</a> <a
+ href="cctiff.html#p1">SourceProfile.icm</a> <a
+ href="cctiff.html#p1">DisplayA.icm</a> <a href="cctiff.html#p2">DisplayA.cal</a>
+ <a href="cctiff.html#p3">infile.tif</a> <a href="cctiff.html#p4">outfile.tif</a><br>
+ or<br>
+ <a href="cctiff.html">cctiff</a> <a
+ href="cctiff.html#p1">SourceProfile.icm</a> <a
+ href="cctiff.html#p1">DisplayA.icm</a> <a href="cctiff.html#p2">DisplayA.cal</a>
+ <a href="cctiff.html#p3">infile.jpg</a> <a href="cctiff.html#p4">outfile.jpg</a><br>
+ <span style="font-weight: bold;"></span><br>
+ <hr size="2" width="100%">
+ <h3><a name="PS1"></a>Profiling Scanners and other input devices
+ such as cameras<br>
+ </h3>
+ Because a scanner or camera is an input device, it is necessary to
+ go about profiling it in quite a different way to an output device.
+ To profile it, a test chart is needed to exercise the input device
+ response, to which the CIE values for each test patch is known.
+ Generally standard reflection or transparency test charts are used
+ for this purpose.<br>
+ <h4><a name="PS2"></a>Types of test charts</h4>
+ The most common and popular test chart for scanner profiling is the
+ IT8.7/2 chart. This is a standard format chart generally reproduced
+ on photographic film, containing about 264 test patches.<br>
+ An accessible and affordable source of such targets is Wolf Faust a
+ <a href="http://www.targets.coloraid.de/">www.coloraid.de</a>.<br>
+ Another source is LaserSoft <a
+ href="http://www.silverfast.com/show/it8/en.html">www.silverfast.com.</a><br>
+ The Kodak Q-60 Color Input Target is also a typical example:<br>
+ <br>
+ <img src="Q60.jpg" alt="Kodak Q60 chart image" height="141"
+ width="200"> <br>
+ <br>
+ A very simple chart that is widely available is the Macbeth
+ ColorChecker chart, although it contains only 24 patches and
+ therefore is probably not ideal for creating profiles:<br>
+ <img alt="ColorChecker 24 patch" src="colorchecker.jpg"
+ style="width: 112px; height: 78px;"><br>
+ <br>
+ Other popular charts are the X-Rite/GretagMacbeth ColorChecker DC
and <a href="http://www.xrite.com/product_overview.aspx?ID=938">ColorChecker @@ -891,20 +883,18 @@ - - - - SG</a> charts:<br> - <br> - <img src="DC.jpg" alt="GretagMacbeth ColorChecker DC chart" - width="200" height="122"> <img alt="ColorChecker SG" src="SG.jpg" - style="width: 174px; height: 122px;"><br> - <br> - The GretagMacbeth Eye-One Pro Scan Target 1.4 can also be used:<br> - <br> - <img alt="Eye-One Scan Target 1.4" src="i1scan14.jpg" style="border: - 2px solid ; width: 200px; height: 140px;"><br> - <br> +
+ SG</a> charts:<br>
+ <br>
+ <img src="DC.jpg" alt="GretagMacbeth ColorChecker DC chart"
+ height="122" width="200"> <img alt="ColorChecker SG" src="SG.jpg"
+ style="width: 174px; height: 122px;"><br>
+ <br>
+ The GretagMacbeth Eye-One Pro Scan Target 1.4 can also be used:<br>
+ <br>
+ <img alt="Eye-One Scan Target 1.4" src="i1scan14.jpg" style="border:
+ 2px solid ; width: 200px; height: 140px;"><br>
+ <br>
Also supported is the <a href="http://www.hutchcolor.com/hct.htm">HutchColor @@ -962,25 +952,23 @@ - - - - HCT</a> :<br> - <br> - <img alt="HutchColor HCT" src="HCT.jpg" style="width: 182px; height: - 140px;"><br> - <br> - <br> - and <a href="http://www.cmp-color.fr/DT3.html">Christophe - Métairie's Digital TargeT 003</a> and <a - href="http://www.cmp-color.fr/digital%20target.html">Christophe - Métairie's Digital Target - 4</a> :<br> - <br> - <img alt="CMP_DT_003" src="CMP_DT_003.jpg" style="width: 186px; - height: 141px;"> <img style="width: 203px; height: 140px;" - alt="CMP_Digital_Target-4" src="CMP_Digital_Target-4.jpg" - width="203" height="140"><br> - <br> +
+ HCT</a> :<br>
+ <br>
+ <img alt="HutchColor HCT" src="HCT.jpg" style="width: 182px; height:
+ 140px;"><br>
+ <br>
+ <br>
+ and <a href="http://www.cmp-color.fr/DT3.html">Christophe
+ Métairie's Digital TargeT 003</a> and <a
+ href="http://www.cmp-color.fr/digital%20target.html">Christophe
+ Métairie's Digital Target - 4</a> :<br>
+ <br>
+ <img alt="CMP_DT_003" src="CMP_DT_003.jpg" style="width: 186px;
+ height: 141px;"> <img style="width: 203px; height: 140px;"
+ alt="CMP_Digital_Target-4" src="CMP_Digital_Target-4.jpg"
+ height="140" width="203"><br>
+ <br>
and the <a href="http://www.silverfast.com/show/dc-targets/en.html">LaserSoft @@ -1038,28 +1026,20 @@ - - - - Imaging DCPro Target</a>:<br> - <br> - <img style="width: 153px; height: 122px;" alt="LaserSoft DCPro - Target" src="LSDC.jpg"><br> - <br> - The Datacolor <a - href="http://spyder.datacolor.com/product-cb-spydercheckr.php">SpyderCheckr</a>:<br> - <br> - <img style=" width: 146px; height: 109px;" alt="Datacolor - SpyderCheckr" src="SpyderChecker.jpg"><br> - <br> - The Datacolor <a - href="http://spyder.datacolor.com/portfolio-view/spydercheckr-24/">SpyderCheckr24</a>:<br> - <br> - <img alt="SpyderCheckr24" src="SpyderChecker24.jpg" width="82" - height="122"><br> - <br> - One of the QPcard's:<br> - <a +
+ Imaging DCPro Target</a>:<br>
+ <br>
+ <img style="width: 153px; height: 122px;" alt="LaserSoft DCPro
+ Target" src="LSDC.jpg"><br>
+ <br>
+ The Datacolor <a
+ href="http://spyder.datacolor.com/product-cb-spydercheckr.php">SpyderCheckr</a>:<br>
+ <br>
+ <img style=" width: 146px; height: 109px;" alt="Datacolor
+ SpyderCheckr" src="SpyderChecker.jpg"><br>
+ <br>
+ One of the QPcard's:<br>
+ <a
href="http://www.qpcard.com/en_b2c/color-reference-cards/qpcard201.html">QPcard @@ -1111,10 +1091,8 @@ - - - - 201</a>: <a +
+ 201</a>: <a
href="http://www.qpcard.com/en_b2c/color-reference-cards/instant-camera-raw-profiling-with-qpcard-202.html">QPcard @@ -1166,89 +1144,87 @@ href="http://www.qpcard.com/en_b2c/color-reference-cards/instant-camera-raw-prof - - - - 202</a>:<br> - <br> - <img style=" width: 41px; height: 141px;" alt="QPCard201" - src="QPcard201.jpg"> - <img - style=" width: 97px; height: 141px;" alt="QPcard202" - src="QPcard202.jpg"><br> - <br> - <h4><a name="PS3"></a>Taking readings from a scanner or camera<br> - </h4> - The test chart you are using needs to be placed on the scanner, and - the scanner needs to be configured to a suitable state, and restored - to that same state when used subsequently with the resulting - profile. For a camera, the chart needs to be lit in a controlled and - even manner using the light source that will be used for subsequent - photographs, and should be shot so as to minimise any geometric - distortion, although the <a href="scanin.html#p">scanin -p</a> flag - may be used to compensate for some degree of distortion. As with any - color profiling task, it is important to setup a known and - repeatable image processing flow, to ensure that the resulting - profile will be usable.<br> - <br> - The chart should be captured and saved to a TIFF format file. I will - assume the resulting file is called scanner.tif. The raster file - need only be roughly cropped so as to contain the test chart - (including the charts edges).<br> - <br> - The second step is to extract the RGB values from the scanner.tif - file, and match then to the reference CIE values. To locate the - patch values in the scan, the <b>scanin</b> tool needs to be given - a template <a href="File_Formats.html#.cht">.cht</a> file that - describes the features of the chart, and how the test patches are - labeled. Also needed is a file containing the CIE values for each of - the patches in the chart, which is typically supplied with the - chart, available from the manufacturers web site, or has been - measured using a spectrometer.<br> - <br> - <div style="margin-left: 40px;">For an IT8.7/2 chart, this is the <span - style="font-weight: bold;">ref/</span><b>it8.cht</b> file - supplied with Argyll, and the manufacturer will will supply - an individual or batch average file along with the chart - containing this information, or downloadable from their web site. - For instance, Kodak Q60 target reference files are <a - href="ftp://ftp.kodak.com/gastds/Q60DATA/">here</a>.<br> - NOTE that the reference file for the IT8.7/2 chart supplied with <span - style="font-weight: bold;">Monaco EZcolor</span> can be - obtained by unzipping the .mrf file. (You may have to make a copy - of the file with a .zip extension to do this.)<br> - <br> - For the ColorChecker 24 patch chart, the <span - style="font-weight: bold;">ref/ColorChecker.cht</span> file - should be used, and there is also a <span style="font-weight: - bold;">ref/ColorChecker.cie</span> file provided that is based - on the manufacturers reference values for the chart. You can also - create your own reference file using an instrument and chartread, - making use of the chart reference file <span style="font-weight: - bold;">ref/ColorChecker.ti2</span>:<br> - <a href="chartread.html">chartread</a> -n - ColorChecker.ti2<br> - Note that due to the small number of patches, a profile created - from such a chart is not likely to be very detailed.<br> - <br> - For the ColorChecker DC chart, the <span style="font-weight: - bold;">ref/ColorCheckerDC.cht</span> file should be used, and - there will be a ColorCheckerDC reference file supplied by - X-Rite/GretagMacbeth with the chart.<br> - <br> - The ColorChecker SG is relatively expensive, but is preferred by - many people because (like the ColorChecker and ColorCheckerDC) its - colors are composed of multiple different pigments, giving it - reflective spectra that are more representative of the real world, - unlike many other charts that are created out of combination of 3 - or 4 colorants.<br> - A limited CIE reference file is available from X-Rite <a -href="http://www.xrite.com/documents/apps/public/digital_colorchecker_sg_l_a_b.txt">here</a>, - but it is not in the usual CGATS format. To convert it to a CIE - reference file useful for <span style="font-weight: bold;">scanin</span>, - you will need to edit the X-Rite file using a <span - style="text-decoration: underline;">plain text</span> editor, - first deleting everything before the line starting with "A1" and +
+ 202</a>:<br>
+ <br>
+ <img style=" width: 41px; height: 141px;" alt="QPCard201"
+ src="QPcard201.jpg">
+ <img
+ style=" width: 97px; height: 141px;" alt="QPcard202"
+ src="QPcard202.jpg"><br>
+ <br>
+ <h4><a name="PS3"></a>Taking readings from a scanner or camera<br>
+ </h4>
+ The test chart you are using needs to be placed on the scanner, and
+ the scanner needs to be configured to a suitable state, and restored
+ to that same state when used subsequently with the resulting
+ profile. For a camera, the chart needs to be lit in a controlled and
+ even manner using the light source that will be used for subsequent
+ photographs, and should be shot so as to minimise any geometric
+ distortion, although the <a href="scanin.html#p">scanin -p</a> flag
+ may be used to compensate for some degree of distortion. As with any
+ color profiling task, it is important to setup a known and
+ repeatable image processing flow, to ensure that the resulting
+ profile will be usable.<br>
+ <br>
+ The chart should be captured and saved to a TIFF format file. I will
+ assume the resulting file is called scanner.tif. The raster file
+ need only be roughly cropped so as to contain the test chart
+ (including the charts edges).<br>
+ <br>
+ The second step is to extract the RGB values from the scanner.tif
+ file, and match then to the reference CIE values. To locate the
+ patch values in the scan, the <b>scanin</b> tool needs to be given
+ a template <a href="File_Formats.html#.cht">.cht</a> file that
+ describes the features of the chart, and how the test patches are
+ labeled. Also needed is a file containing the CIE values for each of
+ the patches in the chart, which is typically supplied with the
+ chart, available from the manufacturers web site, or has been
+ measured using a spectrometer.<br>
+ <br>
+ <div style="margin-left: 40px;">For an IT8.7/2 chart, this is the <span
+ style="font-weight: bold;">ref/</span><b>it8.cht</b> file
+ supplied with Argyll, and the manufacturer will will supply
+ an individual or batch average file along with the chart
+ containing this information, or downloadable from their web site.
+ For instance, Kodak Q60 target reference files are <a
+ href="ftp://ftp.kodak.com/gastds/Q60DATA/">here</a>.<br>
+ NOTE that the reference file for the IT8.7/2 chart supplied with <span
+ style="font-weight: bold;">Monaco EZcolor</span> can be
+ obtained by unzipping the .mrf file. (You may have to make a copy
+ of the file with a .zip extension to do this.)<br>
+ <br>
+ For the ColorChecker 24 patch chart, the <span
+ style="font-weight: bold;">ref/ColorChecker.cht</span> file
+ should be used, and there is also a <span style="font-weight:
+ bold;">ref/ColorChecker.cie</span> file provided that is based
+ on the manufacturers reference values for the chart. You can also
+ create your own reference file using an instrument and chartread,
+ making use of the chart reference file <span style="font-weight:
+ bold;">ref/ColorChecker.ti2</span>:<br>
+ <a href="chartread.html">chartread</a> -n
+ ColorChecker.ti2<br>
+ Note that due to the small number of patches, a profile created
+ from such a chart is not likely to be very detailed.<br>
+ <br>
+ For the ColorChecker DC chart, the <span style="font-weight:
+ bold;">ref/ColorCheckerDC.cht</span> file should be used, and
+ there will be a ColorCheckerDC reference file supplied by
+ X-Rite/GretagMacbeth with the chart.<br>
+ <br>
+ The ColorChecker SG is relatively expensive, but is preferred by
+ many people because (like the ColorChecker and ColorCheckerDC) its
+ colors are composed of multiple different pigments, giving it
+ reflective spectra that are more representative of the real world,
+ unlike many other charts that are created out of combination of 3
+ or 4 colorants.<br>
+ A limited CIE reference file is available from X-Rite <a
+href="http://www.xrite.com/documents/apps/public/digital_colorchecker_sg_l_a_b.txt">here</a>,
+ but it is not in the usual CGATS format. To convert it to a CIE
+ reference file useful for <span style="font-weight: bold;">scanin</span>,
+ you will need to edit the X-Rite file using a <span
+ style="text-decoration: underline;">plain text</span> editor,
+ first deleting everything before the line starting with "A1" and
everything after "N10", then prepending <a href="SG_header.txt">this @@ -1305,95 +1281,83 @@ href="http://www.xrite.com/documents/apps/public/digital_colorchecker_sg_l_a_b.t - - - - header</a>, and appending <a href="SG_footer.txt">this footer</a>, - making sure there are no blank lines inserted in the process. - There are reports that X-Rite have experimented with different ink - formulations for certain patches, so the above reference may not - be as accurate as desired, and it is preferable to measure your - own chart using a spectrometer, if you have the capability.<br> - If you do happen to have access to a more comprehensive instrument - measurement of the ColorChecker SG, or you have measured it - yourself using a color instrument,<br> - then you <span style="text-decoration: underline;">may</span> - need to convert the reference information from spectral <span - style="font-weight: bold;">ColorCheckerSG.txt</span> file to CIE - value <span style="font-weight: bold;">ColorCheckerSG.cie</span> - reference file, follow the following steps:<br> - <a href="txt2ti3.html">txt2ti3</a> - ColorCheckerSG.txt ColorCheckerSG<br> - <a href="spec2cie.html">spec2cie</a> - ColorCheckerSG.ti3 ColorCheckerSG.cie<br> - <br> - For the Eye-One Pro Scan Target 1.4 chart, the <span - style="font-weight: bold;"><span style="font-weight: bold;">ref/</span>i1_RGB_Scan_1.4.cht</span> - file should be used, and as there is no reference file - accompanying this chart, the chart needs to be read with an - instrument (usually the Eye-One Pro). This can be done using - chartread, making use of the chart reference file <span - style="font-weight: bold;">ref/i1_RGB_Scan_1.4.ti2</span>:<br> - <a href="chartread.html">chartread</a> -n - i1_RGB_Scan_1.4<br> - and then rename the resulting <span style="font-weight: bold;">i1_RGB_Scan_1.4.ti3</span> - file to <span style="font-weight: bold;">i1_RGB_Scan_1.4.cie</span><br> - <span style="font-weight: bold;"></span><br> - For the HutchColor HCT chart, the <span style="font-weight: - bold;"><span style="font-weight: bold;">ref/</span>Hutchcolor.cht</span> - file should be used, and the reference <span style="font-weight: - bold;">.txt</span> file downloaded from the HutchColor website.<br> - <br> - For the Christophe Métairie's Digital TargeT 003 chart with 285 - patches, the <span style="font-weight: bold;"><span - style="font-weight: bold;">ref/</span>CMP_DT_003.cht</span> - file should be used, and the cie reference <span - style="font-weight: bold;"></span>files come with the chart.<br> - <br> - For the Christophe Métairie's Digital Target-4 chart with 570 - patches, the <span style="font-weight: bold;">ref/CMP_Digital_Target-4.cht</span> - file should be used, and the cie reference <span - style="font-weight: bold;"></span>files come with the chart.<br> - <br> - For the LaserSoft DCPro chart, the <span style="font-weight: - bold;">ref/LaserSoftDCPro.cht</span> file should be used, and - reference <span style="font-weight: bold;">.txt</span> file - downloaded from the <a - href="http://www.silverfast.com/it8calibration/">Silverfast - website</a>.<br> - <br> - For the Datacolor SpyderCheckr, the <span style="font-weight: - bold;">ref/SpyderChecker.cht</span> file should be used, and a - reference <span style="font-weight: bold;">ref/SpyderChecker.cie - </span>file made from measuring a sample chart is also available. - Alternately you could create your own reference file by - transcribing the <a - href="http://spyder.datacolor.com/images/photo_checkr_colordatainfo.jpg">values</a> - on the Datacolor website. <br> - <br> - For the Datacolor SpyderCheckr, the <span style="font-weight: - bold;">ref/SpyderChecker24.cht</span> file should be used, and a - reference <span style="font-weight: bold;">ref/SpyderChecker24.cie - - </span>file made from measuring a sample chart is also available. - Alternately you could create your own reference file by - transcribing the <a - href="http://spyder.datacolor.com/images/photo_checkr_colordatainfo.jpg">values</a> - on the Datacolor website. <br> - <br> - For the QPCard 201, the <span style="font-weight: bold;">ref/QPcard_201.cht</span> - file should be used, and a reference <span style="font-weight: - bold;">ref/QPcard_201.cie</span> file made from measuring a - sample chart is also available. <br> - <br> - For the QPCard 202, the <span style="font-weight: bold;">ref/QPcard_202.cht</span> - file should be used, and a reference <span style="font-weight: - bold;">ref/QPcard_202.cie</span> file made from measuring a - sample chart is also available. <br> - </div> - <br> - For any other type of chart, a chart recognition template file will - need to be created (this is beyond the scope of the current +
+ header</a>, and appending <a href="SG_footer.txt">this footer</a>,
+ making sure there are no blank lines inserted in the process.
+ There are reports that X-Rite have experimented with different ink
+ formulations for certain patches, so the above reference may not
+ be as accurate as desired, and it is preferable to measure your
+ own chart using a spectrometer, if you have the capability.<br>
+ If you do happen to have access to a more comprehensive instrument
+ measurement of the ColorChecker SG, or you have measured it
+ yourself using a color instrument,<br>
+ then you <span style="text-decoration: underline;">may</span>
+ need to convert the reference information from spectral <span
+ style="font-weight: bold;">ColorCheckerSG.txt</span> file to CIE
+ value <span style="font-weight: bold;">ColorCheckerSG.cie</span>
+ reference file, follow the following steps:<br>
+ <a href="txt2ti3.html">txt2ti3</a>
+ ColorCheckerSG.txt ColorCheckerSG<br>
+ <a href="spec2cie.html">spec2cie</a>
+ ColorCheckerSG.ti3 ColorCheckerSG.cie<br>
+ <br>
+ For the Eye-One Pro Scan Target 1.4 chart, the <span
+ style="font-weight: bold;"><span style="font-weight: bold;">ref/</span>i1_RGB_Scan_1.4.cht</span>
+ file should be used, and as there is no reference file
+ accompanying this chart, the chart needs to be read with an
+ instrument (usually the Eye-One Pro). This can be done using
+ chartread, making use of the chart reference file <span
+ style="font-weight: bold;">ref/i1_RGB_Scan_1.4.ti2</span>:<br>
+ <a href="chartread.html">chartread</a> -n
+ i1_RGB_Scan_1.4<br>
+ and then rename the resulting <span style="font-weight: bold;">i1_RGB_Scan_1.4.ti3</span>
+ file to <span style="font-weight: bold;">i1_RGB_Scan_1.4.cie</span><br>
+ <span style="font-weight: bold;"></span><br>
+ For the HutchColor HCT chart, the <span style="font-weight:
+ bold;"><span style="font-weight: bold;">ref/</span>Hutchcolor.cht</span>
+ file should be used, and the reference <span style="font-weight:
+ bold;">.txt</span> file downloaded from the HutchColor website.<br>
+ <br>
+ For the Christophe Métairie's Digital TargeT 003 chart with 285
+ patches, the <span style="font-weight: bold;"><span
+ style="font-weight: bold;">ref/</span>CMP_DT_003.cht</span>
+ file should be used, and the cie reference <span
+ style="font-weight: bold;"></span>files come with the chart.<br>
+ <br>
+ For the Christophe Métairie's Digital Target-4 chart with 570
+ patches, the <span style="font-weight: bold;">ref/CMP_Digital_Target-4.cht</span>
+ file should be used, and the cie reference <span
+ style="font-weight: bold;"></span>files come with the chart.<br>
+ <br>
+ For the LaserSoft DCPro chart, the <span style="font-weight:
+ bold;">ref/LaserSoftDCPro.cht</span> file should be used, and
+ reference <span style="font-weight: bold;">.txt</span> file
+ downloaded from the <a
+ href="http://www.silverfast.com/it8calibration/">Silverfast
+ website</a>.<br>
+ <br>
+ For the Datacolor SpyderCheckr, the <span style="font-weight:
+ bold;">ref/SpyderChecker.cht</span> file should be used, and a
+ reference <span style="font-weight: bold;">ref/SpyderChecker.cie
+ </span>file made from measuring a sample chart is also available.
+ Alternately you could create your own reference file by
+ transcribing the <a
+ href="http://spyder.datacolor.com/images/photo_checkr_colordatainfo.jpg">values</a>
+ on the Datacolor website. <br>
+ <br>
+ For the QPCard 201, the <span style="font-weight: bold;">ref/QPcard_201.cht</span>
+ file should be used, and a reference <span style="font-weight:
+ bold;">ref/QPcard_201.cie</span> file made from measuring a
+ sample chart is also available. <br>
+ <br>
+ For the QPCard 202, the <span style="font-weight: bold;">ref/QPcard_202.cht</span>
+ file should be used, and a reference <span style="font-weight:
+ bold;">ref/QPcard_202.cie</span> file made from measuring a
+ sample chart is also available. <br>
+ </div>
+ <br>
+ For any other type of chart, a chart recognition template file will
+ need to be created (this is beyond the scope of the current
documentation, although see the <a href="cht_format.html">.cht_format @@ -1450,405 +1414,403 @@ href="http://www.xrite.com/documents/apps/public/digital_colorchecker_sg_l_a_b.t - - - - documentation</a>).<br> - <br> - To create the scanner .ti3 file, run the <b>scanin</b> tool as - follows (assuming an IT8 chart is being used):<br> - <br> - <a href="scanin.html"> scanin</a> -v scanner.tif It8.cht It8ref.txt<br> - <br> - "It8ref.txt" or "It8ref.cie" is assumed to be the name of the CIE - reference file supplied by the chart manufacturer. The resulting - file will be named "<b>scanner.ti3</b>".<br> - <br> - <span style="font-weight: bold;">scanin</span> will process 16 bit - per component .tiff files, which (if the scanner is capable of - creating such files), may improve the quality of the profile. - <br> - <br> - If you have any doubts about the correctness of the chart - recognition, or the subsequent profile's delta E report is unusual, - then use the scanin diagnostic flags <a href="scanin.html#d">-dipn</a> - and examine the <span style="font-weight: bold;">diag.tif</span> - diagnostic file, to make sure that the patches are identified and - aligned correctly. If you have problems getting good automatic - alignment, then consider doing a manual alignment by locating the - fiducial marks on your scan, and feeding them into scanin <a - href="scanin.html#F">-F</a> parameters. The fiducial marks should - be listed in a clockwise direction starting at the top left.<br> - <h4><a name="PS4"></a>Creating a scanner or camera input profile</h4> - Similar to a display profile, an input profile can be either a - shaper/matrix or LUT based profile. Well behaved input devices will - probably give the best results with a shaper/matrix profile, and - this may also be the best choice if your test chart has a small or - unevenly distributed set of test patchs (ie. the IT8.7.2). If a - shaper/matrix profile is a poor fit, consider using a LUT type - profile.<br> - <br> - When creating a LUT type profile, there is the choice of XYZ or - L*a*b* PCS (Device independent, Profile Connection Space). Often for - input devices, it is better to choose the XYZ PCS, as this may be a - better fit given that input devices are usually close to being - linearly additive in behaviour.<br> - <br> - If the purpose of the input profile is to use it as a substitute for - a colorimeter, then the <b>-u</b> flag should be used to avoid - clipping values above the white point. Unless the shaper/matrix type - profile is a very good fit, it is probably advisable to use a LUT - type profile in this situation.<br> - <br> - To create a matrix/shaper profile, the following suffices:<br> - <br> - <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a> - <a href="colprof.html#E">-D"Scanner</a> <a href="colprof.html#E">A"</a> - <a href="colprof.html#q">-qm</a> <a href="colprof.html#a">-as</a> <a - href="colprof.html#p1">scanner</a><br> - <br> - For an XYZ PCS LUT based profile then the following would be used:<br> - <br> - <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a> - <a href="colprof.html#E">-D"Scanner A"</a> <a href="colprof.html#q">-qm</a> - <a href="colprof.html#a">-ax</a> <a href="colprof.html#p1">scanner</a><br> - <br> - For the purposes of a poor mans colorimeter, the following would - generally be used:<br> - <br> - <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a> - <a href="colprof.html#E">-D"Scanner A"</a> <a href="colprof.html#q">-qm</a> - <a href="colprof.html#a">-ax</a> <a href="colprof.html#u">-u</a> <a - href="colprof.html#p1">scanner</a><br> - <br> - Make sure you check the delta E report at the end of the profile - creation, to see if the sample data and profile is behaving - reasonably. Depending on the type of device, and the consistency of - the readings, average errors of 5 or less, and maximum errors of 15 - or less would normally be expected. If errors are grossly higher - than this, then this is an indication that something is seriously - wrong with the device measurement, or profile creation.<br> - <br> - If profiling a <span style="font-weight: bold;">camera</span> in <span - style="font-weight: bold;">RAW</span> mode, then there may be some - advantage in creating a pure matrix only profile, in which it is - assumed that the camera response is completely linear. This may - reduce extrapolation artefacts. If setting the white point will be - done in some application, then it may also be an advantage to use - the <span style="font-weight: bold;">-u</span> flag and avoid - setting the white point to that of the profile chart:<br> - <br> - <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a> - <a href="colprof.html#E">-D"Camera"</a> <a href="colprof.html#q">-qm</a> - <a href="colprof.html#a">-am</a> <a href="colprof.html#u">-u</a> <a - href="colprof.html#p1">scanner</a><br> - <br> - <br> - <hr size="2" width="100%"> - <h3><a name="PP1"></a>Profiling Printers<br> - </h3> - The overall process is to create a set of device measurement target - values, print them out, measure them, and then create an ICC profile - from the measurements. If the printer is an RGB based printer, then - the process is only slightly more complicated than profiling a - display. If the printer is CMYK based, then some additional - parameters are required to set the total ink limit (TAC) and - black generation curve.<br> - <h4><a name="PP2"></a>Creating a print profile test chart</h4> - The first step in profiling any output device, is to create a set of - device colorspace test values. The important parameters needed are:<br> - <ul> - <li>What colorspace does the device use ?</li> - <li>How many test patches do I want to use/what paper size do I - want to use ?</li> - <li>What instrument am I going to use to read the patches ?<br> - </li> - <li>If it is a CMYK device, what is the total ink limit ?<br> - </li> - <li>What information do I already have about how the device - behaves ?</li> - </ul> - Most printers running through simple drivers will appear as if they - are RGB devices. In fact there is no such thing as a real RGB - printer, since printers use white media and the colorant must - subtract from the light reflected on it to create color, but the - printer itself turns the incoming RGB into the native print - colorspace, so for this reason we will tell targen to use the "Print - RGB" colorspace, so that it knows that it's really a subtractive - media. Other drivers will drive a printer more directly, and will - expect a CMYK profile. [Currently Argyll is not capable of creating - an ICC profile for devices with more colorants than CMYK. When this - capability is introduced, it will by creating an additional - separation profile which then allows the printer to be treated as a - CMY or CMYK printer.] One way of telling what sort of profile is - expected for your device is to examine an existing profile for that - device using <a href="http://www.argyllcms.com/doc/iccdump.html">iccdump</a>.<br> - <br> - The number of test patches will depend somewhat on what quality - profile you want to make, how well behaved the printer is, as well - as the effort needed to read the number of test values. Generally it - is convenient to fill a certain paper size with the maximum number - of test values that will fit.<br> - <br> - At a minimum, for an "RGB" device, a few hundred values are needed - (400-1000). For high quality CMYK profiles, 1000-3000 is not an - unreasonable number of patches.<br> - <br> - To assist the determination of test patch values, it can help to - have a rough idea of how the device behaves, so that the device test - point locations can be pre-conditioned. This could be in the form of - an ICC profile of a similar device, or a lower quality, or previous - profile for that particular device. If one were going to make a very - high quality Lut based profile, then it might be worthwhile to make - up a smaller, preliminary shaper/matrix profile using a few hundred - test points, before embarking on testing the device with several - thousand.<br> - <br> - The documentation for the <a - href="http://www.argyllcms.com/doc/targen.html">targen</a> tool - lists a <a href="http://www.argyllcms.com/doc/targen.html#Table">table</a> - of paper sizes and number of patches for typical situations.<br> - <br> - For a CMYK device, a total ink limit usually needs to be specified. - Sometimes a device will have a maximum total ink limit set by its - manufacturer or operator, and some CMYK systems (such as chemical - proofing systems) don't have any limit. Typical printing devices - such as Xerographic printers, inkjet printers and printing presses - will have a limit. The exact procedure for determining an ink limit - is outside the scope of this document, but one way of going about - this might be to generate some small (say a few hundred patches) - with targen & pritntarg with different total ink limits, and - printing them out, making the ink limit as large as possible without - striking problems that are caused by too much ink.<br> - <br> - Generally one wants to use the maximum possible amount of ink to - maximize the gamut available on the device. For most CMYK devices, - an ink limit between 200 and 400 is usual, but and ink limit of 250% - or over is generally desirable for reasonably dense blacks and dark - saturated colors. And ink limit of less than 200% will begin to - compromise the fully saturated gamut, as secondary colors (ie - combinations of any two primary colorants) will not be able to reach - full strength.<br> - <br> - Once an ink limit is used in printing the characterization test - chart for a device, it becomes a critical parameter in knowing what - the characterized gamut of the device is. If after printing the test - chart, a greater ink limit were to be used, the the software would - effectively be extrapolating the device behaviour at total ink - levels beyond that used in the test chart, leading to inaccuracies.<br> - <br> - Generally in Argyll, the ink limit is established when creating the - test chart values, and then carried through the profile making - process automatically. Once the profile has been made however, the - ink limit is no longer recorded, and you, the user, will have to - keep track of it if the ICC profile is used in any program than - needs to know the usable gamut of the device.<br> - <br> - <br> - Lets consider two devices in our examples, "PrinterA" which is an - "RGB" device, and "PrinterB" which is CMYK, and has a target ink - limit of 250%. <br> - <br> - The simplest approach is to make a set of test values that is - independent of the characteristics of the particular device:<br> - <br> - <a href="targen.html">targen</a> <a href="targen.html#v">-v</a> - <a href="targen.html#d">-d2</a> <a href="targen.html#f">-f1053</a> - <a href="targen.html#p1">PrinterA</a><br> - <br> - <a href="targen.html">targen</a> <a href="targen.html#v">-v</a> - <a href="targen.html#d">-d4</a> <a href="targen.html#l">-l260</a> - <a href="targen.html#f">-f1053</a> <a href="targen.html#p1">PrinterB</a><br> - <br> - The number of patches chosen here happens to be right for an A4 - paper size being read using a Spectroscan instrument. See the <a - href="targen.html#Table">table</a> in the <a - href="targen.html">targen</a> documentation for some other - suggested numbers.<br> - <br> - If there is a preliminary or previous profile called "OldPrinterA" - available, and we want to try creating a "pre-conditioned" set of - test values that will more efficiently sample the device response, - then the following would achieve this:<u><br> - </u><br> - <a href="targen.html">targen</a> <a href="targen.html#v">-v</a> - <a href="targen.html#d">-d2</a> <a href="targen.html#f">-f1053</a> - <a href="targen.html#c">-c OldPrinterA</a> <a - href="targen.html#p1">PrinterA</a><br> - <br> - <a href="targen.html">targen</a> <a href="targen.html#v">-v</a> - <a href="targen.html#d">-d4</a> <a href="targen.html#l">-l260</a> - <a href="targen.html#f">-f1053</a> <a href="targen.html#c">-c - OldPrinterB</a> <a href="targen.html#p1">PrinterB</a><br> - <a href="targen.html#p1"></a><br> - <br> - The output of <b>targen</b> will be the file PrinterA.ti1 and - PrinterB.ti1 respectively, containing the device space test values, - as well as expected CIE values used for chart recognition purposes.<br> - <br> - <h4><a name="PP2b"></a>Printing a print profile test chart<br> - <br> - </h4> - The next step is turn the test values in to a PostScript or TIFF - raster test file that can printed on the device. The basic - information that needs to be supplied is the type of instrument that - will be used to read the patches, as well as the paper size it is to - be formatted for.<br> - <br> - For an X-Rite DTP41, the following would be typical:<br> - <br> - <a href="printtarg.html">printtarg</a> <a href="printtarg.html#v">-v</a> - <a href="printtarg.html#i">-i41</a> <a href="printtarg.html#p">-pA4</a> - <a href="printtarg.html#p1">PrinterA</a><br> - <br> - For a Gretag Eye-One Pro, the following would be typical:<br> - <br> - <a href="printtarg.html">printtarg</a> <a href="printtarg.html#v">-v</a> - <a href="printtarg.html#i">-ii1</a> <a href="printtarg.html#p">-pA4</a> - <a href="printtarg.html#p1">PrinterA</a><br> - <br> - For using with a scanner as a colorimeter, the Gretag Spectroscan - layout is suitable, but the <a href="printtarg.html#s">-s</a> flag - should be used so as to generate a layout suitable for scan - recognition, as well as generating the scan recognition template - files. (You probably want to use less patches with <span - style="font-weight: bold;">targen</span>, when using the <span - style="font-weight: bold;">printtarg -s</span> flag, e.g. 1026 - patches for an A4R page, etc.) The following would be typical:<br> - <br> - <a href="printtarg.html">printtarg</a> <a href="printtarg.html#v">-v</a> - <a href="printtarg.html#s">-s</a> <a href="printtarg.html#i">-iSS</a> - <a href="printtarg.html#p">-pA4R</a> <a href="printtarg.html#p1">PrinterA</a><br> - <span style="font-weight: bold;"><br> - printtarg</span> reads the PrinterA.ti1 file, creates a - PrinterA.ti2 file containing the layout information as well as the - device values and expected CIE values, as well as a PrinterA.ps file - containing the test chart. If the <span style="font-weight: bold;">-s</span> - flag is used, one or more PrinterA.cht files is created to allow the - <a href="scanin.html">scanin</a> program to recognize the chart.<br> - <br> - To create TIFF raster files rather than PostScript, use the <a - href="printtarg.html#t"><span style="font-weight: bold;">-t</span></a> - flag.<br> - <br> - <span style="font-weight: bold;">GSview</span> is a good program to - use to check what the PostScript file will look like, without - actually printing it out. You could also use <span - style="font-weight: bold;">Photoshop</span> or <span - style="font-weight: bold;">ImageMagick</span> for this purpose.<br> - <br> - The last step is to print the chart out.<br> - <br> - Using a suitable PostScript or raster file printing program, - downloader, print the chart. If you are not using a TIFF test chart, - and you do not have a PostScript capable printer, then an - interpreter like GhostScript or even Photoshop could be used to - rasterize the file into something that can be printed. Note that it - is important that the PostScript interpreter or TIFF printing - application and printer configuration is setup for a device - profiling run, and that any sort of color conversion of color - correction be turned off so that the device values in the PostScript - or TIFF file are sent directly to the device. If the device has a - calibration system, then it would be usual to have setup and - calibrated the device before starting the profiling run, and to - apply calibration to the chart values. If Photoshop was to be used, - then either the chart needs to be a single page, or separate .eps or - .tiff files for each page should be used, so that they can be - converted and printed one at a time (see the <a - href="printtarg.html#e">-e</a> and <a href="printtarg.html#t">-t</a> - flags).<br> - <br> - <h4><a name="PP3"></a>Reading a print test chart using an instrument</h4> - Once the test chart has been printed, the color of the patches needs - to be read using a suitable instrument.<br> - <br> - Several different instruments are currently supported, some that - need to be used patch by patch, some read a strip at a time, and - some read a sheet at a time. See <a href="instruments.html">instruments</a> - for a current list.<br> - <br> - The instrument needs to be connected to your computer before running - the <a href="chartread.html">chartread</a> command. Both serial - port and USB connected Instruments are supported. A serial port to - USB adapter might have to be used if your computer doesn't have any - serial ports, and you have a serial interface connected instrument.<br> - <br> - If you run <a href="chartread.html">chartread</a> so as to print - out its usage message (ie. by using a <span style="font-weight: - bold;">-?</span> or <span style="font-weight: bold;">--</span> - flags), then it will list any identified serial ports or USB - connected instruments, and their corresponding number for the <a - href="chartread.html#c">-c</a> option. By default, <a - href="chartread.html">chartread</a> will try to connect to the - first available USB instrument, or an instrument on the first serial - port.<br> - <br> - The only arguments required is to specify the basename of the .ti2 - file. If a non-default serial port is to be used, then the <span - style="font-weight: bold;">-c</span> option would also be - specified.<br> - <br> - e.g. for a Spectroscan on the second port:<br> - <br> - <a href="chartread.html">chartread</a> <a href="chartread.html#c">-c2</a> - <a href="chartread.html#p1">PrinterA</a><br> - <br> - For a DTP41 to the default serial port:<br> - <br> - <a href="chartread.html">chartread</a><a href="chartread.html#i"></a> - <a href="chartread.html#p1">PrinterA</a><br> - <br> - <span style="font-weight: bold;">chartread</span> will interactively - prompt you through the process of reading each sheet or strip. See <a - href="chartread.html">chartread</a> for more details on the - responses for each type of instrument. Continue with <a - href="Scenarios.html#PP5">Creating a printer profile</a>.<br> - <br> - <h4><a name="PP4"></a>Reading a print test chart using a scanner or - camera<br> - </h4> - <br> - Argyll supports using a scanner or even a camera as a substitute for - a colorimeter. While a scanner or camera is no replacement for a - color measurement instrument, it may give acceptable results in some - situations, and may give better results than a generic profile for a - printing device.<br> - <br> - The main limitation of the scanner-as-colorimeter approach are:<br> - <br> - * The scanner dynamic range and/or precision may not match the - printers or what is required for a good profile.<br> - * The spectral interaction of the scanner test chart and printer - test chart with the scanner spectral response can cause color - errors.<br> - * Spectral differences caused by different black amounts in the - print test chart can cause color errors. <br> - * The scanner reference chart gamut may be much smaller than the - printers gamut, making the scanner profile too inaccurate to be - useful. <br> - <br> - As well as some of the above, a camera may not be suitable if it - automatically adjusts exposure or white point when taking a picture, - and this behavior cannot be disabled.<br> - <br> - The end result is often a profile that has a noticeable color cast, - compared to a profile created using a colorimeter or spectrometer.<br> - <br> - <br> - It is assumed that you have created a scanner or camera profile - following the <a - href="http://www.argyllcms.com/doc/Scenarios.html#PS1">procedure</a> - outline above. For best possible results it is advisable to both - profile the scanner or camera, and use it in scanning the printed - test chart, in as "raw" mode as possible (i.e. using 16 bits per - component images, if the scanner or camera is capable of doing so; - not setting white or black points, using a fixed exposure etc.). It - is generally advisable to create a LUT type input profile, and use - the <a href="http://www.argyllcms.com/doc/colprof.html#u">-u</a> - flag to avoid clipping scanned value whiter than the input - calibration chart.<br> - <br> - Scan or photograph your printer chart (or charts) on the scanner or +
+ documentation</a>).<br>
+ <br>
+ To create the scanner .ti3 file, run the <b>scanin</b> tool as
+ follows (assuming an IT8 chart is being used):<br>
+ <br>
+ <a href="scanin.html"> scanin</a> -v scanner.tif It8.cht It8ref.txt<br>
+ <br>
+ "It8ref.txt" or "It8ref.cie" is assumed to be the name of the CIE
+ reference file supplied by the chart manufacturer. The resulting
+ file will be named "<b>scanner.ti3</b>".<br>
+ <br>
+ <span style="font-weight: bold;">scanin</span> will process 16 bit
+ per component .tiff files, which (if the scanner is capable of
+ creating such files), may improve the quality of the profile.
+ <br>
+ <br>
+ If you have any doubts about the correctness of the chart
+ recognition, or the subsequent profile's delta E report is unusual,
+ then use the scanin diagnostic flags <a href="scanin.html#d">-dipn</a>
+ and examine the <span style="font-weight: bold;">diag.tif</span>
+ diagnostic file, to make sure that the patches are identified and
+ aligned correctly. If you have problems getting good automatic
+ alignment, then consider doing a manual alignment by locating the
+ fiducial marks on your scan, and feeding them into scanin <a
+ href="scanin.html#F">-F</a> parameters. The fiducial marks should
+ be listed in a clockwise direction starting at the top left.<br>
+ <h4><a name="PS4"></a>Creating a scanner or camera input profile</h4>
+ Similar to a display profile, an input profile can be either a
+ shaper/matrix or LUT based profile. Well behaved input devices will
+ probably give the best results with a shaper/matrix profile, and
+ this may also be the best choice if your test chart has a small or
+ unevenly distributed set of test patchs (ie. the IT8.7.2). If a
+ shaper/matrix profile is a poor fit, consider using a LUT type
+ profile.<br>
+ <br>
+ When creating a LUT type profile, there is the choice of XYZ or
+ L*a*b* PCS (Device independent, Profile Connection Space). Often for
+ input devices, it is better to choose the XYZ PCS, as this may be a
+ better fit given that input devices are usually close to being
+ linearly additive in behaviour.<br>
+ <br>
+ If the purpose of the input profile is to use it as a substitute for
+ a colorimeter, then the <b>-u</b> flag should be used to avoid
+ clipping values above the white point. Unless the shaper/matrix type
+ profile is a very good fit, it is probably advisable to use a LUT
+ type profile in this situation.<br>
+ <br>
+ To create a matrix/shaper profile, the following suffices:<br>
+ <br>
+ <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a>
+ <a href="colprof.html#E">-D"Scanner</a> <a href="colprof.html#E">A"</a>
+ <a href="colprof.html#q">-qm</a> <a href="colprof.html#a">-as</a> <a
+ href="colprof.html#p1">scanner</a><br>
+ <br>
+ For an XYZ PCS LUT based profile then the following would be used:<br>
+ <br>
+ <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a>
+ <a href="colprof.html#E">-D"Scanner A"</a> <a href="colprof.html#q">-qm</a>
+ <a href="colprof.html#a">-ax</a> <a href="colprof.html#p1">scanner</a><br>
+ <br>
+ For the purposes of a poor mans colorimeter, the following would
+ generally be used:<br>
+ <br>
+ <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a>
+ <a href="colprof.html#E">-D"Scanner A"</a> <a href="colprof.html#q">-qm</a>
+ <a href="colprof.html#a">-ax</a> <a href="colprof.html#u">-u</a> <a
+ href="colprof.html#p1">scanner</a><br>
+ <br>
+ Make sure you check the delta E report at the end of the profile
+ creation, to see if the sample data and profile is behaving
+ reasonably. Depending on the type of device, and the consistency of
+ the readings, average errors of 5 or less, and maximum errors of 15
+ or less would normally be expected. If errors are grossly higher
+ than this, then this is an indication that something is seriously
+ wrong with the device measurement, or profile creation.<br>
+ <br>
+ If profiling a <span style="font-weight: bold;">camera</span> in <span
+ style="font-weight: bold;">RAW</span> mode, then there may be some
+ advantage in creating a pure matrix only profile, in which it is
+ assumed that the camera response is completely linear. This may
+ reduce extrapolation artefacts. If setting the white point will be
+ done in some application, then it may also be an advantage to use
+ the <span style="font-weight: bold;">-u</span> flag and avoid
+ setting the white point to that of the profile chart:<br>
+ <br>
+ <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a>
+ <a href="colprof.html#E">-D"Camera"</a> <a href="colprof.html#q">-qm</a>
+ <a href="colprof.html#a">-am</a> <a href="colprof.html#u">-u</a> <a
+ href="colprof.html#p1">scanner</a><br>
+ <br>
+ <br>
+ <hr size="2" width="100%">
+ <h3><a name="PP1"></a>Profiling Printers<br>
+ </h3>
+ The overall process is to create a set of device measurement target
+ values, print them out, measure them, and then create an ICC profile
+ from the measurements. If the printer is an RGB based printer, then
+ the process is only slightly more complicated than profiling a
+ display. If the printer is CMYK based, then some additional
+ parameters are required to set the total ink limit (TAC) and
+ black generation curve.<br>
+ <h4><a name="PP2"></a>Creating a print profile test chart</h4>
+ The first step in profiling any output device, is to create a set of
+ device colorspace test values. The important parameters needed are:<br>
+ <ul>
+ <li>What colorspace does the device use ?</li>
+ <li>How many test patches do I want to use/what paper size do I
+ want to use ?</li>
+ <li>What instrument am I going to use to read the patches ?<br>
+ </li>
+ <li>If it is a CMYK device, what is the total ink limit ?<br>
+ </li>
+ <li>What information do I already have about how the device
+ behaves ?</li>
+ </ul>
+ Most printers running through simple drivers will appear as if they
+ are RGB devices. In fact there is no such thing as a real RGB
+ printer, since printers use white media and the colorant must
+ subtract from the light reflected on it to create color, but the
+ printer itself turns the incoming RGB into the native print
+ colorspace, so for this reason we will tell targen to use the "Print
+ RGB" colorspace, so that it knows that it's really a subtractive
+ media. Other drivers will drive a printer more directly, and will
+ expect a CMYK profile. [Currently Argyll is not capable of creating
+ an ICC profile for devices with more colorants than CMYK. When this
+ capability is introduced, it will by creating an additional
+ separation profile which then allows the printer to be treated as a
+ CMY or CMYK printer.] One way of telling what sort of profile is
+ expected for your device is to examine an existing profile for that
+ device using <a href="http://www.argyllcms.com/doc/iccdump.html">iccdump</a>.<br>
+ <br>
+ The number of test patches will depend somewhat on what quality
+ profile you want to make, how well behaved the printer is, as well
+ as the effort needed to read the number of test values. Generally it
+ is convenient to fill a certain paper size with the maximum number
+ of test values that will fit.<br>
+ <br>
+ At a minimum, for an "RGB" device, a few hundred values are needed
+ (400-1000). For high quality CMYK profiles, 1000-3000 is not an
+ unreasonable number of patches.<br>
+ <br>
+ To assist the determination of test patch values, it can help to
+ have a rough idea of how the device behaves, so that the device test
+ point locations can be pre-conditioned. This could be in the form of
+ an ICC profile of a similar device, or a lower quality, or previous
+ profile for that particular device. If one were going to make a very
+ high quality Lut based profile, then it might be worthwhile to make
+ up a smaller, preliminary shaper/matrix profile using a few hundred
+ test points, before embarking on testing the device with several
+ thousand.<br>
+ <br>
+ The documentation for the <a
+ href="http://www.argyllcms.com/doc/targen.html">targen</a> tool
+ lists a <a href="http://www.argyllcms.com/doc/targen.html#Table">table</a>
+ of paper sizes and number of patches for typical situations.<br>
+ <br>
+ For a CMYK device, a total ink limit usually needs to be specified.
+ Sometimes a device will have a maximum total ink limit set by its
+ manufacturer or operator, and some CMYK systems (such as chemical
+ proofing systems) don't have any limit. Typical printing devices
+ such as Xerographic printers, inkjet printers and printing presses
+ will have a limit. The exact procedure for determining an ink limit
+ is outside the scope of this document, but one way of going about
+ this might be to generate some small (say a few hundred patches)
+ with targen & pritntarg with different total ink limits, and
+ printing them out, making the ink limit as large as possible without
+ striking problems that are caused by too much ink.<br>
+ <br>
+ Generally one wants to use the maximum possible amount of ink to
+ maximize the gamut available on the device. For most CMYK devices,
+ an ink limit between 200 and 400 is usual, but and ink limit of 250%
+ or over is generally desirable for reasonably dense blacks and dark
+ saturated colors. And ink limit of less than 200% will begin to
+ compromise the fully saturated gamut, as secondary colors (ie
+ combinations of any two primary colorants) will not be able to reach
+ full strength.<br>
+ <br>
+ Once an ink limit is used in printing the characterization test
+ chart for a device, it becomes a critical parameter in knowing what
+ the characterized gamut of the device is. If after printing the test
+ chart, a greater ink limit were to be used, the the software would
+ effectively be extrapolating the device behaviour at total ink
+ levels beyond that used in the test chart, leading to inaccuracies.<br>
+ <br>
+ Generally in Argyll, the ink limit is established when creating the
+ test chart values, and then carried through the profile making
+ process automatically. Once the profile has been made however, the
+ ink limit is no longer recorded, and you, the user, will have to
+ keep track of it if the ICC profile is used in any program than
+ needs to know the usable gamut of the device.<br>
+ <br>
+ <br>
+ Lets consider two devices in our examples, "PrinterA" which is an
+ "RGB" device, and "PrinterB" which is CMYK, and has a target ink
+ limit of 250%. <br>
+ <br>
+ The simplest approach is to make a set of test values that is
+ independent of the characteristics of the particular device:<br>
+ <br>
+ <a href="targen.html">targen</a> <a href="targen.html#v">-v</a>
+ <a href="targen.html#d">-d2</a> <a href="targen.html#f">-f1053</a>
+ <a href="targen.html#p1">PrinterA</a><br>
+ <br>
+ <a href="targen.html">targen</a> <a href="targen.html#v">-v</a>
+ <a href="targen.html#d">-d4</a> <a href="targen.html#l">-l260</a>
+ <a href="targen.html#f">-f1053</a> <a href="targen.html#p1">PrinterB</a><br>
+ <br>
+ The number of patches chosen here happens to be right for an A4
+ paper size being read using a Spectroscan instrument. See the <a
+ href="targen.html#Table">table</a> in the <a
+ href="targen.html">targen</a> documentation for some other
+ suggested numbers.<br>
+ <br>
+ If there is a preliminary or previous profile called "OldPrinterA"
+ available, and we want to try creating a "pre-conditioned" set of
+ test values that will more efficiently sample the device response,
+ then the following would achieve this:<u><br>
+ </u><br>
+ <a href="targen.html">targen</a> <a href="targen.html#v">-v</a>
+ <a href="targen.html#d">-d2</a> <a href="targen.html#f">-f1053</a>
+ <a href="targen.html#c">-c OldPrinterA</a> <a
+ href="targen.html#p1">PrinterA</a><br>
+ <br>
+ <a href="targen.html">targen</a> <a href="targen.html#v">-v</a>
+ <a href="targen.html#d">-d4</a> <a href="targen.html#l">-l260</a>
+ <a href="targen.html#f">-f1053</a> <a href="targen.html#c">-c
+ OldPrinterB</a> <a href="targen.html#p1">PrinterB</a><br>
+ <a href="targen.html#p1"></a><br>
+ <br>
+ The output of <b>targen</b> will be the file PrinterA.ti1 and
+ PrinterB.ti1 respectively, containing the device space test values,
+ as well as expected CIE values used for chart recognition purposes.<br>
+ <br>
+ <h4><a name="PP2b"></a>Printing a print profile test chart<br>
+ <br>
+ </h4>
+ The next step is turn the test values in to a PostScript or TIFF
+ raster test file that can printed on the device. The basic
+ information that needs to be supplied is the type of instrument that
+ will be used to read the patches, as well as the paper size it is to
+ be formatted for.<br>
+ <br>
+ For an X-Rite DTP41, the following would be typical:<br>
+ <br>
+ <a href="printtarg.html">printtarg</a> <a href="printtarg.html#v">-v</a>
+ <a href="printtarg.html#i">-i41</a> <a href="printtarg.html#p">-pA4</a>
+ <a href="printtarg.html#p1">PrinterA</a><br>
+ <br>
+ For a Gretag Eye-One Pro, the following would be typical:<br>
+ <br>
+ <a href="printtarg.html">printtarg</a> <a href="printtarg.html#v">-v</a>
+ <a href="printtarg.html#i">-ii1</a> <a href="printtarg.html#p">-pA4</a>
+ <a href="printtarg.html#p1">PrinterA</a><br>
+ <br>
+ For using with a scanner as a colorimeter, the Gretag Spectroscan
+ layout is suitable, but the <a href="printtarg.html#s">-s</a> flag
+ should be used so as to generate a layout suitable for scan
+ recognition, as well as generating the scan recognition template
+ files. (You probably want to use less patches with <span
+ style="font-weight: bold;">targen</span>, when using the <span
+ style="font-weight: bold;">printtarg -s</span> flag, e.g. 1026
+ patches for an A4R page, etc.) The following would be typical:<br>
+ <br>
+ <a href="printtarg.html">printtarg</a> <a href="printtarg.html#v">-v</a>
+ <a href="printtarg.html#s">-s</a> <a href="printtarg.html#i">-iSS</a>
+ <a href="printtarg.html#p">-pA4R</a> <a href="printtarg.html#p1">PrinterA</a><br>
+ <span style="font-weight: bold;"><br>
+ printtarg</span> reads the PrinterA.ti1 file, creates a
+ PrinterA.ti2 file containing the layout information as well as the
+ device values and expected CIE values, as well as a PrinterA.ps file
+ containing the test chart. If the <span style="font-weight: bold;">-s</span>
+ flag is used, one or more PrinterA.cht files is created to allow the
+ <a href="scanin.html">scanin</a> program to recognize the chart.<br>
+ <br>
+ To create TIFF raster files rather than PostScript, use the <a
+ href="printtarg.html#t"><span style="font-weight: bold;">-t</span></a>
+ flag.<br>
+ <br>
+ <span style="font-weight: bold;">GSview</span> is a good program to
+ use to check what the PostScript file will look like, without
+ actually printing it out. You could also use <span
+ style="font-weight: bold;">Photoshop</span> or <span
+ style="font-weight: bold;">ImageMagick</span> for this purpose.<br>
+ <br>
+ The last step is to print the chart out.<br>
+ <br>
+ Using a suitable PostScript or raster file printing program,
+ downloader, print the chart. If you are not using a TIFF test chart,
+ and you do not have a PostScript capable printer, then an
+ interpreter like GhostScript or even Photoshop could be used to
+ rasterize the file into something that can be printed. Note that it
+ is important that the PostScript interpreter or TIFF printing
+ application and printer configuration is setup for a device
+ profiling run, and that any sort of color conversion of color
+ correction be turned off so that the device values in the PostScript
+ or TIFF file are sent directly to the device. If the device has a
+ calibration system, then it would be usual to have setup and
+ calibrated the device before starting the profiling run, and to
+ apply calibration to the chart values. If Photoshop was to be used,
+ then either the chart needs to be a single page, or separate .eps or
+ .tiff files for each page should be used, so that they can be
+ converted and printed one at a time (see the <a
+ href="printtarg.html#e">-e</a> and <a href="printtarg.html#t">-t</a>
+ flags).<br>
+ <br>
+ <h4><a name="PP3"></a>Reading a print test chart using an instrument</h4>
+ Once the test chart has been printed, the color of the patches needs
+ to be read using a suitable instrument.<br>
+ <br>
+ Several different instruments are currently supported, some that
+ need to be used patch by patch, some read a strip at a time, and
+ some read a sheet at a time. See <a href="instruments.html">instruments</a>
+ for a current list.<br>
+ <br>
+ The instrument needs to be connected to your computer before running
+ the <a href="chartread.html">chartread</a> command. Both serial
+ port and USB connected Instruments are supported. A serial port to
+ USB adapter might have to be used if your computer doesn't have any
+ serial ports, and you have a serial interface connected instrument.<br>
+ <br>
+ If you run <a href="chartread.html">chartread</a> so as to print
+ out its usage message (ie. by using a <span style="font-weight:
+ bold;">-?</span> or <span style="font-weight: bold;">--</span>
+ flags), then it will list any identified serial ports or USB
+ connected instruments, and their corresponding number for the <a
+ href="chartread.html#c">-c</a> option. By default, <a
+ href="chartread.html">chartread</a> will try to connect to the
+ first available USB instrument, or an instrument on the first serial
+ port.<br>
+ <br>
+ The only arguments required is to specify the basename of the .ti2
+ file. If a non-default serial port is to be used, then the <span
+ style="font-weight: bold;">-c</span> option would also be
+ specified.<br>
+ <br>
+ e.g. for a Spectroscan on the second port:<br>
+ <br>
+ <a href="chartread.html">chartread</a> <a href="chartread.html#c">-c2</a>
+ <a href="chartread.html#p1">PrinterA</a><br>
+ <br>
+ For a DTP41 to the default serial port:<br>
+ <br>
+ <a href="chartread.html">chartread</a><a href="chartread.html#i"></a>
+ <a href="chartread.html#p1">PrinterA</a><br>
+ <br>
+ <span style="font-weight: bold;">chartread</span> will interactively
+ prompt you through the process of reading each sheet or strip. See <a
+ href="chartread.html">chartread</a> for more details on the
+ responses for each type of instrument. Continue with <a
+ href="Scenarios.html#PP5">Creating a printer profile</a>.<br>
+ <br>
+ <h4><a name="PP4"></a>Reading a print test chart using a scanner or
+ camera<br>
+ </h4>
+ <br>
+ Argyll supports using a scanner or even a camera as a substitute for
+ a colorimeter. While a scanner or camera is no replacement for a
+ color measurement instrument, it may give acceptable results in some
+ situations, and may give better results than a generic profile for a
+ printing device.<br>
+ <br>
+ The main limitation of the scanner-as-colorimeter approach are:<br>
+ <br>
+ * The scanner dynamic range and/or precision may not match the
+ printers or what is required for a good profile.<br>
+ * The spectral interaction of the scanner test chart and printer
+ test chart with the scanner spectral response can cause color
+ errors.<br>
+ * Spectral differences caused by different black amounts in the
+ print test chart can cause color errors. <br>
+ * The scanner reference chart gamut may be much smaller than the
+ printers gamut, making the scanner profile too inaccurate to be
+ useful. <br>
+ <br>
+ As well as some of the above, a camera may not be suitable if it
+ automatically adjusts exposure or white point when taking a picture,
+ and this behavior cannot be disabled.<br>
+ <br>
+ The end result is often a profile that has a noticeable color cast,
+ compared to a profile created using a colorimeter or spectrometer.<br>
+ <br>
+ <br>
+ It is assumed that you have created a scanner or camera profile
+ following the <a
+ href="http://www.argyllcms.com/doc/Scenarios.html#PS1">procedure</a>
+ outline above. For best possible results it is advisable to both
+ profile the scanner or camera, and use it in scanning the printed
+ test chart, in as "raw" mode as possible (i.e. using 16 bits per
+ component images, if the scanner or camera is capable of doing so;
+ not setting white or black points, using a fixed exposure etc.). It
+ is generally advisable to create a LUT type input profile, and use
+ the <a href="http://www.argyllcms.com/doc/colprof.html#u">-u</a>
+ flag to avoid clipping scanned value whiter than the input
+ calibration chart.<br>
+ <br>
+ Scan or photograph your printer chart (or charts) on the scanner or
camera previously profiled. <big><span style="font-weight: bold;">The @@ -1906,100 +1868,98 @@ href="http://www.xrite.com/documents/apps/public/digital_colorchecker_sg_l_a_b.t - - - - scanner or camera must be configured and used exactly the same - as it was when it was profiled.</span></big><br> - <br> - I will assume the resulting scan/photo input file is called <span - style="font-weight: bold;">PrinterB.tif</span> (or <span - style="font-weight: bold;">PrinterB1.tif</span>, <span - style="font-weight: bold;">PrinterB2.tif</span> etc. in the case - of multiple charts). As with profiling the scanner or camera, the - raster file need only be roughly cropped so as to contain the test - chart.<br> - <br> - The scanner recognition files created when <span - style="font-weight: bold;">printtarg</span> was run is assumed to - be called <span style="font-weight: bold;">PrinterB.cht</span>. - Using the scanner profile created previously (assumed to be called <span - style="font-weight: bold;">scanner.icm</span>), the printer test - chart scan patches are converted to CIE values using the <span - style="font-weight: bold;">scanin</span> tool:<br> - <br> - <a href="scanin.html">scanin</a> <a href="scanin.html#v">-v</a> <a - href="scanin.html#c">-c</a> <a href="scanin.html#cp1">PrinterB.tif</a> - <a href="scanin.html#cp2">PrinterB.cht</a> <a - href="scanin.html#cp3">scanner.icm</a> <a href="scanin.html#cp4">PrinterB</a><br> - <br> - If there were multiple test chart pages, the results would be - accumulated page by page using the <a href="scanin.html#ca">-ca</a> - option, ie., if there were 3 pages:<br> - <br> - <a href="scanin.html">scanin</a> <a href="scanin.html#v">-v</a> <a - href="scanin.html#c">-c</a> <a href="scanin.html#cp1">PrinterB1.tif</a> - <a href="scanin.html#cp2">PrinterB1.cht</a> <a - href="scanin.html#cp3">scanner.icm</a> <a href="scanin.html#cp4">PrinterB</a><br> - <a href="scanin.html">scanin</a> <a href="scanin.html#v">-v</a> <a - href="scanin.html#ca">-ca</a> <a href="scanin.html#cp1">PrinterB2.tif</a> - <a href="scanin.html#cp2">PrinterB2.cht</a> <a - href="scanin.html#cp3">scanner.icm</a> <a href="scanin.html#cp4">PrinterB</a><br> - <a href="scanin.html">scanin</a> <a href="scanin.html#v">-v</a> <a - href="scanin.html#ca">-ca</a> <a href="scanin.html#cp1">PrinterB3.tif</a> - <a href="scanin.html#cp2">PrinterB3.cht</a> <a - href="scanin.html#cp3">scanner.icm</a> <a href="scanin.html#cp4">PrinterB</a><br> - <br> - Now that the <span style="font-weight: bold;">PrinterB.ti3</span> - data has been obtained, the profile continue in the next section - with <span style="font-weight: bold;">Creating a printer profile</span>.<br> - <br> - If you have any doubts about the correctness of the chart - recognition, or the subsequent profile's delta E report is unusual, - then use the scanin diagnostic flags <a href="scanin.html#d">-dipn</a> - and examine the <span style="font-weight: bold;">diag.tif</span> - diagnostic file.<br> - <h4><a name="PP5"></a>Creating a printer profile<br> - </h4> - Creating an RGB based printing profile is very similar to creating a - display device profile. For a CMYK printer, some additional - information is needed to set the black generation.<br> - <br> - Where the resulting profile will be used conventionally (ie. using <a - href="collink.html">collink</a> <a href="collink.html#s">-s</a>, - or <a href="cctiff.html">cctiff</a> or most other "dumb" CMMs) it - is important to specify that gamut mapping should be computed for - the output (B2A) perceptual and saturation tables. This is done by - specifying a device profile as the parameter to the <a - href="colprof.html">colprof</a> <a href="colprof.html#S">-S</a> - flag. When you intend to create a "general use" profile, it can be a - good technique to specify the source gamut as the opposite type of - profile to that being created, i.e. if a printer profile is being - created, specify a display profile (e.g. sRGB) as the source gamut. - If a display profile is being created, then specify a printer - profile as the source (e.g. Figra, SWOP etc.). When linking to - the profile you have created this way as the output profile, then - use perceptual intent if the source is the opposite type, and - relative colorimetric if it is the same type.<br> - <br> - "Opposite type of profile" refers to the native gamut of the device, - and what its fundamental nature is, additive or subtractive. An - emissive display will have additive primaries (R, G & B), while - a reflective print, will have subtractive primaries (C, M, Y & - possibly others), irrespective of what colorspace the printer is - driven in (a printer might present an RGB interface, but internally - this will be converted to CMY, and it will have a CMY type of - gamut). Because of the complimentary nature of additive and - subtractive device primary colorants, these types of devices have - the most different gamuts, and hence need the most gamut mapping to - convert from one colorspace to the other.<br> - <br> - If you are creating a profile for a specific purpose, intending to - link it to a specific input profile, then you will get the best - results by specifying that source profile as the source gamut.<br> - <br> - If a profile is only going to be used as an input profile, or is - going to be used with a "smart" CMM (e.g. <a href="collink.html">collink</a> +
+ scanner or camera must be configured and used exactly the same
+ as it was when it was profiled.</span></big><br>
+ <br>
+ I will assume the resulting scan/photo input file is called <span
+ style="font-weight: bold;">PrinterB.tif</span> (or <span
+ style="font-weight: bold;">PrinterB1.tif</span>, <span
+ style="font-weight: bold;">PrinterB2.tif</span> etc. in the case
+ of multiple charts). As with profiling the scanner or camera, the
+ raster file need only be roughly cropped so as to contain the test
+ chart.<br>
+ <br>
+ The scanner recognition files created when <span
+ style="font-weight: bold;">printtarg</span> was run is assumed to
+ be called <span style="font-weight: bold;">PrinterB.cht</span>.
+ Using the scanner profile created previously (assumed to be called <span
+ style="font-weight: bold;">scanner.icm</span>), the printer test
+ chart scan patches are converted to CIE values using the <span
+ style="font-weight: bold;">scanin</span> tool:<br>
+ <br>
+ <a href="scanin.html">scanin</a> <a href="scanin.html#v">-v</a> <a
+ href="scanin.html#c">-c</a> <a href="scanin.html#cp1">PrinterB.tif</a>
+ <a href="scanin.html#cp2">PrinterB.cht</a> <a
+ href="scanin.html#cp3">scanner.icm</a> <a href="scanin.html#cp4">PrinterB</a><br>
+ <br>
+ If there were multiple test chart pages, the results would be
+ accumulated page by page using the <a href="scanin.html#ca">-ca</a>
+ option, ie., if there were 3 pages:<br>
+ <br>
+ <a href="scanin.html">scanin</a> <a href="scanin.html#v">-v</a> <a
+ href="scanin.html#c">-c</a> <a href="scanin.html#cp1">PrinterB1.tif</a>
+ <a href="scanin.html#cp2">PrinterB1.cht</a> <a
+ href="scanin.html#cp3">scanner.icm</a> <a href="scanin.html#cp4">PrinterB</a><br>
+ <a href="scanin.html">scanin</a> <a href="scanin.html#v">-v</a> <a
+ href="scanin.html#ca">-ca</a> <a href="scanin.html#cp1">PrinterB2.tif</a>
+ <a href="scanin.html#cp2">PrinterB2.cht</a> <a
+ href="scanin.html#cp3">scanner.icm</a> <a href="scanin.html#cp4">PrinterB</a><br>
+ <a href="scanin.html">scanin</a> <a href="scanin.html#v">-v</a> <a
+ href="scanin.html#ca">-ca</a> <a href="scanin.html#cp1">PrinterB3.tif</a>
+ <a href="scanin.html#cp2">PrinterB3.cht</a> <a
+ href="scanin.html#cp3">scanner.icm</a> <a href="scanin.html#cp4">PrinterB</a><br>
+ <br>
+ Now that the <span style="font-weight: bold;">PrinterB.ti3</span>
+ data has been obtained, the profile continue in the next section
+ with <span style="font-weight: bold;">Creating a printer profile</span>.<br>
+ <br>
+ If you have any doubts about the correctness of the chart
+ recognition, or the subsequent profile's delta E report is unusual,
+ then use the scanin diagnostic flags <a href="scanin.html#d">-dipn</a>
+ and examine the <span style="font-weight: bold;">diag.tif</span>
+ diagnostic file.<br>
+ <h4><a name="PP5"></a>Creating a printer profile<br>
+ </h4>
+ Creating an RGB based printing profile is very similar to creating a
+ display device profile. For a CMYK printer, some additional
+ information is needed to set the black generation.<br>
+ <br>
+ Where the resulting profile will be used conventionally (ie. using <a
+ href="collink.html">collink</a> <a href="collink.html#s">-s</a>,
+ or <a href="cctiff.html">cctiff</a> or most other "dumb" CMMs) it
+ is important to specify that gamut mapping should be computed for
+ the output (B2A) perceptual and saturation tables. This is done by
+ specifying a device profile as the parameter to the <a
+ href="colprof.html">colprof</a> <a href="colprof.html#S">-S</a>
+ flag. When you intend to create a "general use" profile, it can be a
+ good technique to specify the source gamut as the opposite type of
+ profile to that being created, i.e. if a printer profile is being
+ created, specify a display profile (e.g. sRGB) as the source gamut.
+ If a display profile is being created, then specify a printer
+ profile as the source (e.g. Figra, SWOP etc.). When linking to
+ the profile you have created this way as the output profile, then
+ use perceptual intent if the source is the opposite type, and
+ relative colorimetric if it is the same type.<br>
+ <br>
+ "Opposite type of profile" refers to the native gamut of the device,
+ and what its fundamental nature is, additive or subtractive. An
+ emissive display will have additive primaries (R, G & B), while
+ a reflective print, will have subtractive primaries (C, M, Y &
+ possibly others), irrespective of what colorspace the printer is
+ driven in (a printer might present an RGB interface, but internally
+ this will be converted to CMY, and it will have a CMY type of
+ gamut). Because of the complimentary nature of additive and
+ subtractive device primary colorants, these types of devices have
+ the most different gamuts, and hence need the most gamut mapping to
+ convert from one colorspace to the other.<br>
+ <br>
+ If you are creating a profile for a specific purpose, intending to
+ link it to a specific input profile, then you will get the best
+ results by specifying that source profile as the source gamut.<br>
+ <br>
+ If a profile is only going to be used as an input profile, or is
+ going to be used with a "smart" CMM (e.g. <a href="collink.html">collink</a>
<a href="collink.html#g">-g</a> or <a href="collink.html#G">-G</a>), then @@ -2058,85 +2018,83 @@ then - - - - it can save considerable processing time and space if the -b flag is - used, and the -S flag not used.<br> - <br> - For an RGB printer intended to print RGB originals, the following - might be a typical profile usage:<br> - <br> - <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a> - <a href="colprof.html#E">-D"Printer A"</a> <a href="colprof.html#q">-qm</a> - <a href="colprof.html#S">-S</a><a href="colprof.html#S"> sRGB.icm</a> - <a href="colprof.html#c">-cmt</a> <a href="colprof.html#d">-dpp</a> - <a href="colprof.html#p1">PrinterA</a><br> - <br> - or if you intent to print from Fogra, SWOP or other standard CMYK - style originals:<br> - <br> - <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a> - <a href="colprof.html#E">-D"Printer A"</a> <a href="colprof.html#q">-qm</a> - <a href="colprof.html#S">-S</a><a href="colprof.html#S"> - fogra39l.icm</a> <a href="colprof.html#c">-cmt</a> <a - href="colprof.html#d">-dpp</a> <a href="colprof.html#p1">PrinterA</a><br> - <br> - If you know what colorspace your originals are in, use that as the - argument to <span style="font-weight: bold;">-S</span>.<br> - <br> - If your viewing environment for the display and print doesn't match - the ones implied by the <a href="colprof.html#c">-cmt</a> and <a - href="colprof.html#d">-dpp</a> options, leave them out, and - evaluate what, if any appearance transformation is appropriate for - your environment at a later stage.<br> - <br> - Make sure you check the delta E report at the end of the profile - creation, to see if the sample data and profile is behaving - reasonably. Depending on the type of device, and the consistency of - the readings, average errors of 5 or less, and maximum errors of 15 - or less would normally be expected. If errors are grossly higher - than this, then this is an indication that something is seriously - wrong with the device measurement, or profile creation. - <h4><a name="PP6"></a>Choosing a black generation curve (and other - CMYK printer options)<br> - </h4> - For a CMYK printer, it would be normal to specify the type of black - generation, either as something simple, or as a specific curve. The - documentation in <a href="colprof.html#k">colprof</a> for the - details of the options.<span style="font-weight: bold;"><br> - <br> - Note</span> that making a good choice of black generation curve - can affect things such as: how robust neutrals are given printer - drift or changes in viewing lighting, how visible screening is, and - how smooth looking the B2A conversion is.<br> - <br> - For instance, maximizing the level of K will mean that the neutral - colors are composed of greater amounts of Black ink, and black ink - retains its neutral appearance irrespective of printer behavior or - the spectrum of the illuminant used to view the print. On the other - hand, output which is dominantly from one of the color channels will - tend to emphasize the screening pattern and any unevenness (banding - etc.) of that channel, and the black channel in particular has the - highest visibility. So in practice, some balance between the levels - of the four channels is probably best, with more K if the screening - is fine and a robust neutral balance is important, or less K if the - screening is more visible and neutral balance is less critical. The - levels of K at the edges of the gamut of the device will be fixed by - the nature of the ink combinations that maximize the gamut (ie. - typically zero ink for light chromatic colors, some combination for - dark colors, and a high level of black for very dark near neutrals), - and it is also usually important to set a curve that smoothly - transitions to the K values at the gamut edges. Dramatic changes in - K imply equally dramatic changes in CMY, and these abrupt - transitions will reveal the limited precision and detail that can be - captured in a lookup table based profile, often resulting in a - "bumpy" looking output.<br> - <br> - If you want to experiment with the various black generation - parameters, then it might be a good idea to create a preliminary - profile (using <a href="colprof.html#q">-ql</a> <a - href="colprof.html#b">-b</a> <a href="colprof.html#ni">-no</a>, <a +
+ it can save considerable processing time and space if the -b flag is
+ used, and the -S flag not used.<br>
+ <br>
+ For an RGB printer intended to print RGB originals, the following
+ might be a typical profile usage:<br>
+ <br>
+ <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a>
+ <a href="colprof.html#E">-D"Printer A"</a> <a href="colprof.html#q">-qm</a>
+ <a href="colprof.html#S">-S</a><a href="colprof.html#S"> sRGB.icm</a>
+ <a href="colprof.html#c">-cmt</a> <a href="colprof.html#d">-dpp</a>
+ <a href="colprof.html#p1">PrinterA</a><br>
+ <br>
+ or if you intent to print from Fogra, SWOP or other standard CMYK
+ style originals:<br>
+ <br>
+ <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a>
+ <a href="colprof.html#E">-D"Printer A"</a> <a href="colprof.html#q">-qm</a>
+ <a href="colprof.html#S">-S</a><a href="colprof.html#S">
+ fogra39l.icm</a> <a href="colprof.html#c">-cmt</a> <a
+ href="colprof.html#d">-dpp</a> <a href="colprof.html#p1">PrinterA</a><br>
+ <br>
+ If you know what colorspace your originals are in, use that as the
+ argument to <span style="font-weight: bold;">-S</span>.<br>
+ <br>
+ If your viewing environment for the display and print doesn't match
+ the ones implied by the <a href="colprof.html#c">-cmt</a> and <a
+ href="colprof.html#d">-dpp</a> options, leave them out, and
+ evaluate what, if any appearance transformation is appropriate for
+ your environment at a later stage.<br>
+ <br>
+ Make sure you check the delta E report at the end of the profile
+ creation, to see if the sample data and profile is behaving
+ reasonably. Depending on the type of device, and the consistency of
+ the readings, average errors of 5 or less, and maximum errors of 15
+ or less would normally be expected. If errors are grossly higher
+ than this, then this is an indication that something is seriously
+ wrong with the device measurement, or profile creation.
+ <h4><a name="PP6"></a>Choosing a black generation curve (and other
+ CMYK printer options)<br>
+ </h4>
+ For a CMYK printer, it would be normal to specify the type of black
+ generation, either as something simple, or as a specific curve. The
+ documentation in <a href="colprof.html#k">colprof</a> for the
+ details of the options.<span style="font-weight: bold;"><br>
+ <br>
+ Note</span> that making a good choice of black generation curve
+ can affect things such as: how robust neutrals are given printer
+ drift or changes in viewing lighting, how visible screening is, and
+ how smooth looking the B2A conversion is.<br>
+ <br>
+ For instance, maximizing the level of K will mean that the neutral
+ colors are composed of greater amounts of Black ink, and black ink
+ retains its neutral appearance irrespective of printer behavior or
+ the spectrum of the illuminant used to view the print. On the other
+ hand, output which is dominantly from one of the color channels will
+ tend to emphasize the screening pattern and any unevenness (banding
+ etc.) of that channel, and the black channel in particular has the
+ highest visibility. So in practice, some balance between the levels
+ of the four channels is probably best, with more K if the screening
+ is fine and a robust neutral balance is important, or less K if the
+ screening is more visible and neutral balance is less critical. The
+ levels of K at the edges of the gamut of the device will be fixed by
+ the nature of the ink combinations that maximize the gamut (ie.
+ typically zero ink for light chromatic colors, some combination for
+ dark colors, and a high level of black for very dark near neutrals),
+ and it is also usually important to set a curve that smoothly
+ transitions to the K values at the gamut edges. Dramatic changes in
+ K imply equally dramatic changes in CMY, and these abrupt
+ transitions will reveal the limited precision and detail that can be
+ captured in a lookup table based profile, often resulting in a
+ "bumpy" looking output.<br>
+ <br>
+ If you want to experiment with the various black generation
+ parameters, then it might be a good idea to create a preliminary
+ profile (using <a href="colprof.html#q">-ql</a> <a
+ href="colprof.html#b">-b</a> <a href="colprof.html#ni">-no</a>, <a
href="colprof.html#no">-ni</a> and no <a href="colprof.html#S">-S</a>), @@ -2193,409 +2151,407 @@ then - - - - and then used <a href="xicclu.html#g">xicclu</a> to explore the - effect of the parameters.<br> - <br> - For instance, say we have our CMYK .ti3 file <span - style="font-weight: bold;">PrinterB.ti3</span>. First we make a - preliminary profile called <span style="font-weight: bold;">PrinterBt</span>:<br> - <br> - copy PrinterB.ti3 PrinterBt.ti3 (Use - "cp" on Linux or OSX of course.)<br> - <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a> - <a href="colprof.html#q">-qm</a> <a href="colprof.html#b">-b</a> <a - href="colprof.html#c">-cmt</a> <a href="colprof.html#d">-dpp</a> - <a href="colprof.html#p1">PrinterBt</a><br> - <br> - Then see what the minimum black level down the neutral axis can be. - Note that we need to also set any ink limits we've decided on as - well (coloprof defaulting to 10% less than the value recorded in the - .ti3 file). In this example the test chart has a 300% total ink - limit, and we've decided to use 290%:<br> - <br> - <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a - href="xicclu.html#k">-kz</a> <a href="xicclu.html#l">-l290</a> <a - href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a - href="xicclu.html#p1">PrinterBt.icm</a><br> - <br> - Which might be a graph something like this:<br> - <br> - <img alt="Graph of CMYK neutral axis with minimum K" - src="Kgraph1.jpg" style="width: 250px; height: 250px;"><br> - <br> - Note how the minimum black is zero up to 93% of the - white->black L* curve, and then jumps up to 87%. This is because - we've reached the total ink limit, and K then has to be substituted - for CMY, to keep the total under the total ink limit.<br> - <br> - Then let's see what the maximum black level down the neutral axis - can be:<br> - <br> - <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a - href="xicclu.html#k">-kx</a> <a href="xicclu.html#l">-l290</a> <a - href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a - href="xicclu.html#p1">PrinterBt.icm</a><br> - <br> - Which might be a graph something like this:<br> - <br> - <img alt="Graph of CMYK neutral axis with maximum K" - src="Kgraph2.jpg" style="width: 250px; height: 250px;"><br> - <br> - Note how the CMY values are fairly low up to 93% of the - white->black L* curve (the low levels of CMY are helping set the - neutral color), and then they jump up. This is because we've reach - the point where black on it's own, isn't as dark as the color that - can be achieved using CMY and K. Because the K has a dominant effect - on the hue of the black, the levels of CMY are often fairly volatile - in this region.<br> - <br> - Any K curve we specify must lie between the black curves of the - above two graphs.<br> - <br> - Let's say we'd like to chose a moderate black curve, one that aims - for about equal levels of CMY and K. We should also aim for it to be - fairly smooth, since this will minimize visual artefacts caused by - the limited fidelity that profile LUT tables are able to represent - inside the profile.<br> - <br> - <img style="width: 340px; height: 258px;" alt="-k parameters" - src="Kparams.jpg"><br> - <br> - <br> - For minimum discontinuities we should aim for the curve to finish at - the point it has to reach to satisfy the total ink limit at 87% - curve and 93% black. For a first try we can simply set a straight - line to that point: <br> - <br> - <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a - href="xicclu.html#k">-kp 0 0 .93 .87 1.0</a> <a - href="xicclu.html#l">-l290</a> <a href="xicclu.html#f">-fif</a> <a - href="xicclu.html#i">-ir</a> <a href="xicclu.html#p1">PrinterBt.icm</a><br> - <br> - <img alt="Graph of CMYK neutral axis with kp 0 0 1.0 1.0 1.0 -l290" - src="Kgraph3.jpg" style="width: 250px; height: 250px;"><br> - <br> - The black "curve" hits the 93%/87% mark well, but is a bit too far - above CMY, so we'll try making the black curve concave:<br> - <br> - <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a - href="xicclu.html#k">-kp </a><a href="xicclu.html#k">0 0 .93 .87 - 0.65</a> <a href="xicclu.html#l">-l290</a> <a - href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a - href="xicclu.html#p1">PrinterBt.icm</a><br> - <br> - <img alt="Graph of CMYK neutral axis with -kp 0 .05 1 .9 1 -l290" - src="Kgraph4.jpg" style="width: 250px; height: 249px;"><br> - <br> - This looks just about perfect, so the the curve parameters can now - be used to generate our real profile:<br> - <br> - <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a> - <a href="colprof.html#E">-D"Printer B"</a> <a href="colprof.html#q">-qm</a> - <a href="colprof.html#k">-kp </a><a href="xicclu.html#k">0 0 .93 - .87 0.65</a> <a href="colprof.html#S">-S</a><a - href="colprof.html#S"> sRGB.icm</a> <a href="colprof.html#c">-cmt</a> - <a href="colprof.html#d">-dpp</a> <a href="colprof.html#p1">PrinterB</a><br> - <br> - and the resulting B2A table black curve can be checked using xicclu:<br> - <br> - <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a - href="xicclu.html#f">-fb</a> <a href="xicclu.html#i">-ir</a> <a - href="xicclu.html#p1">PrinterB.icm</a><br> - <br> - <img style="width: 250px; height: 250px;" alt="sadsadas" - src="Kgraph5.jpg"><br> - <br> - <br> - <hr style="margin-left: 0px; margin-right: auto; width: 20%; height: - 2px;"><br> - <span style="font-weight: bold;">Examples of other inkings:<br> - <br> - </span>A smoothed zero black inking:<br> - <br> - <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a - href="xicclu.html#k">-kp </a><a href="xicclu.html#k">0 .7 .93 .87 - 1.0</a> <a href="xicclu.html#l">-l290</a> <a - href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a - href="xicclu.html#p1">PrinterBt.icm</a><br> - <br> - <img style="width: 250px; height: 250px;" alt="sadsadas" - src="Kgraph6.jpg"><br> - <br> - A low black inking:<br> - <br> - <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a - href="xicclu.html#k">-kp </a><a href="xicclu.html#k">0 0 .93 .87 - 0.15</a> <a href="xicclu.html#l">-l290</a> <a - href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a - href="xicclu.html#p1">PrinterBt.icm</a><br> - <br> - <img style="width: 250px; height: 250px;" alt="sadsadas" - src="Kgraph7.jpg"><br> - <br> - <br> - A high black inking:<br> - <br> - <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a - href="xicclu.html#k">-kp </a><a href="xicclu.html#k">0 0 .93 .87 - 1.2</a> <a href="xicclu.html#l">-l290</a> <a - href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a - href="xicclu.html#p1">PrinterBt.icm</a><br> - <br> - <img style="width: 250px; height: 250px;" alt="sadsadas" - src="Kgraph8.jpg"><br> - <br> - <span style="font-weight: bold;"></span> - <h4>Overriding the ink limit<br> - </h4> - Normally the total ink limit will be read from the <span - style="font-weight: bold;">PrinterB.ti3</span> file, and will be - set at a level 10% lower than the number used in creating the test - chart values using <a href="targen.html#l">targen -l</a>. If you - want to override this with a lower limit, then use the <a - href="colprof.html#l">-l flag</a>.<br> - <br> - <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a> - <a href="colprof.html#E">-D"Printer B"</a> <a href="colprof.html#q">-qm</a> - <a href="colprof.html#S">-S</a><a href="colprof.html#S"> sRGB.icm</a> - <a href="colprof.html#c">-cmt</a> <a href="colprof.html#d">-dpp</a> - <a href="colprof.html#k">-kr</a> <a href="xicclu.html#l">-l290</a> - <a href="colprof.html#p1">PrinterB</a><br> - <br> - Make sure you check the delta E report at the end of the profile - creation, to see if the profile is behaving reasonably.<br> - <br> - One way of checking that your ink limit is not too high, is to use "<span - style="font-weight: bold;">xicc -fif -ia</span>" to check, by - setting different ink limits using the <span style="font-weight: - bold;">-l</span> option, feeding Lab = 0 0 0 into it, and checking - the resulting black point. Starting with the ink limit used - with <span style="font-weight: bold;">targen</span> for the test - chart, reduce it until the black point starts to be affected. If it - is immediately affected by any reduction in the ink limit, then the - black point may be improved by increasing the ink limit used to - generate the test chart and then re-print and re-measuring it, - assuming other aspects such as wetness, smudging, spreading or - drying time are not an issue.<br> - <br> - <hr style="width: 100%; height: 2px;"><br> - <h3><a name="PC1"></a>Calibrating Printers<br> - </h3> - <span style="font-weight: bold;">Profiling</span> creates a - description of how a device behaves, while <span - style="font-weight: bold;">calibration</span> on the other hand is - intended to <span style="text-decoration: underline;">change</span> - how a device behaves. Argyll has the ability to create per-channel - device space calibration curves for print devices, that can then be - used to improve the behavior of of the device, making a subsequent - profile fit the device more easily and also allow day to day - correction of device drift without resorting to a full re-profile.<br> - <br> - <span style="font-weight: bold;">NOTE:</span> Because calibration - adds yet another layer to the way color is processed, it is - recommended that it not be attempted until the normal profiling - workflow is established, understood and verified.<br> - <h4><a name="PC2"></a>Calibrated print workflows</h4> - There are two main workflows that printer calibration curves can be - applied to:<br> - <br> - <span style="text-decoration: underline;">Workflow <span - style="font-weight: bold;">with</span> native calibration - capability</span>:<br> - <br> - Firstly the printer itself may have the capability of using per - channel calibration curves. In this situation, the calibration - process will be largely independent of profiling. Firstly the - printer is configured to have both its color management and - calibration disabled (the latter perhaps achieved by loading linear - calibration curves), and a print calibration test chart that - consists of per channel color wedges is printed. The calibration - chart is read and the resulting .ti3 file converted into calibration - curves by processing it using <span style="font-weight: bold;">printcal</span>. - The calibration is then installed into the printer. Subsequent - profiling will be performed on the <span style="text-decoration: - underline;">calibrated</span> printer (ie. the profile test chart - will have the calibration curves applied to it by the printer, and - the resulting ICC profile will represent the behavior of the - calibrated printer.)<br> - <br> - <span style="text-decoration: underline;">Workflow <span - style="font-weight: bold;">without</span> native calibration - capability</span>:<br> - <br> - The second workflow is one in which the printer has no calibration - capability itself. In this situation, the calibration process will - have to be applied using the ICC color management tools, so careful - coordination with profiling is needed. Firstly the printer is - configured to have its color management disabled, and a print - calibration test chart that consists of per channel color wedges is - printed. The calibration chart is converted into calibration curves - by reading it and then processing the resultant .ti3 using <span - style="font-weight: bold;">printcal</span>,. During the subsequent - <span style="text-decoration: underline;">profiling</span>, the - calibration curves will need to be applied to the profile test chart - in the process of using <span style="font-weight: bold;">printtarg</span>. - Once the the profile has been created, then in subsequent printing - the calibration curves will need to be applied to an image being - printed either explicitly when using <span style="font-weight: - bold;">cctiff</span> to apply color profiles <span - style="text-decoration: underline;">and</span> calibration, <span - style="font-weight: bold;">OR</span> by creating a version of the - profile that has had the calibration curves incorporated into it - using the <span style="font-weight: bold;">applycal</span> tool. - The latter is useful when some CMM (color management module) other - than <span style="font-weight: bold;">cctiff </span>is being used.<br> - <br> - Once calibration aim targets for a particular device and mode - (screening, paper etc.) have been established, then the printer can - be re-calibrated at any time to bring its per channel behavior back - into line if it drifts, and the new calibration curves can be - installed into the printer, or re-incorporated into the profile. - - <h4><a name="PC3"></a>Creating a print calibration test chart</h4> - The first step is to create a print calibration test chart. Since - calibration only creates per-channel curves, only single channel - step wedges are required for the chart. The main choice is the - number of steps in each wedge. For simple fast calibrations perhaps - as few as 20 steps per channel may be enough, but for a better - quality of calibration something like 50 or more steps would be a - better choice.<br> - <br> - Let's consider two devices in our examples, "PrinterA" which is an - "RGB" printer device, and "PrinterB" which is CMYK. In fact there is - no such thing as a real RGB printer, since printers use white media - and the colorant must subtract from the light reflected on it to - create color, but the printer itself turns the incoming RGB into the - native print colorspace, so for this reason we are careful to tell - targen to use the "Print RGB" colorspace, so that it knows to create - step wedges from media white to full colorant values.<br> - <br> - For instance, to create a 50 steps per channel calibration test - chart for our RGB and CMYK devices, the following would be - sufficient:<br> - <br> - <a href="targen.html">targen</a> <a href="targen.html#v">-v</a> - <a href="targen.html#d">-d2</a> <a href="targen.html#s">-s50</a> - <a href="targen.html#e">-e3</a> <a href="targen.html#f">-f0</a> <a - href="targen.html#p1">PrinterA_c</a><br> - <br> - <a href="targen.html">targen</a> <a href="targen.html#v">-v</a> - <a href="targen.html#d">-d4</a> <a href="targen.html#s">-s50</a> - <a href="targen.html#e">-e4</a> <a href="targen.html#f">-f0</a> <a - href="targen.html#p1">PrinterB_c</a><br> - <a href="targen.html#p1"></a><br> - For an outline of how to then print and read the resulting test - chart, see <a href="Scenarios.html#PP2b">Printing a print - profile test chart</a>, and <a href="Scenarios.html#PP3">Reading - a print test chart using an instrument</a>. Note that the printer - must be in an un-profiled and un-calibrated mode when doing this - print. Having done this, there will be a PrinterA.ti3 or - PrinterB.ti3 file containing the step wedge calibration chart - readings.<br> - <br> - <span style="font-weight: bold;">NOTE</span> that if you are - calibrating a raw printer driver, and there is considerable dot - gain, then you may want to use the <a href="targen.html#p">-p</a> - parameter to adjust the test chart point distribution to spread them - more evenly in perceptual space, giving more accurate control over - the calibration. Typically this will be a value greater than one for - a device that has dot gain, e.g. values of 1.5, 2.0 or 2.5 might be - good places to start. You can do a preliminary calibration and use - the verbose output of printcal to recommend a suitable value for <span - style="font-weight: bold;">-p</span>.<br> - <h4><a name="PC4"></a>Creating a printer calibration<br> - </h4> - The <a href="printcal.html">printcal</a> tool turns a calibration - chart <a href="File_Formats.html#.ti3">.ti3</a> file into a <a - href="File_Formats.html#.cal">.cal</a> file. It has three main - operating modes:- Initial calibration, Re-Calibration, and - Verification. (A fourth mode, "Imitation" is very like Initial - Calibration, but is used for establishing a calibration target that - a similar printer can attempt to imitate.)<br> - <br> - The distinction between Initial Calibration and Re-Calibration is - that in the initial calibration we establish the "aim points" or - response we want out of the printer after calibration. There are - three basic parameters to set this for each channel: Maximum level, - minimum level, and curve shape.<br> - <br> - By default the maximum level will be set using a heuristic which - attempts to pick the point when there is diminishing returns for - applying more colorant. This can be overridden using the <span - style="font-weight: bold;">-x# percent</span> option, where <span - style="font-weight: bold;">#</span> represents the choice of - channel this will be applied to. The parameter is the percentage of - device maximum. <br> - <br> - The minimum level defaults to 0, but can be overridden using the <span - style="font-weight: bold;">-n# deltaE</span> option. A minimum of - 0 means that zero colorant will correspond to the natural media - color, but it may be desirable to set a non-pure media color using - calibration for the purposes of emulating some other media. The - parameter is in Delta E units.<br> - <br> - The curve shape defaults to being perceptually uniform, which means - that even steps of calibrated device value result in perceptually - even color steps. In some situations it may be desirable to alter - this curve (for instance when non color managed output needs to be - sent to the calibrated printer), and a simple curve shape target can - be set using the <span style="font-weight: bold;">-t# percent</span> - parameter. This affects the output value at 50% input value, and - represents the percentage of perceptual output. By default it is 50% - perceptual output for 50% device input.<br> - <br> - Once a device has been calibrated, it can be re-calibrated to the - same aim target.<br> - <br> - Verification uses a calibration test chart printed through the - calibration, and compares the achieved response to the aim target.<br> - <br> - The simplest possible way of creating the <span style="font-weight: - bold;">PrinterA.cal</span> file is:<br> - <br> - <a href="printcal.html">printcal</a> <a - href="printcal.html#i">-i</a> <a href="colprof.html#p2">PrinterA_c</a><br> - <br> - For more detailed information, you can add the <span - style="font-weight: bold;">-v</span> and <span - style="font-weight: bold;">-p</span> flags:<br> - <br> - <a href="printcal.html">printcal</a> <a - href="printcal.html#v">-v</a> <a href="printcal.html#p">-p</a> <a - href="printcal.html#i">-i</a> <a href="colprof.html#p2">PrinterB_c</a><br> - <br> - (You will need to select the plot window and hit a key to advance - past each plot).<br> - <br> - For re-calibration, the name of the previous calibration file will - need to be supplied, and a new calibration<br> - file will be created:<br> - <br> - <a href="printcal.html">printcal</a> <a - href="printcal.html#v">-v</a> <a href="printcal.html#p">-p</a> <a - href="printcal.html#r">-r</a> <a href="colprof.html#p1">PrinterB_c_old</a> - <a href="colprof.html#p2">PrinterB_c_new</a><br> - <br> - Various aim points are normally set automatically by <span - style="font-weight: bold;">printcal</span>, but these can be - overridden using the <a href="colprof.html#x">-x</a>, <a - href="colprof.html#n">-n</a> and <a href="colprof.html#t">-t</a> - options. e.g. say we wanted to set the maximum ink for Cyan to 80% - and Black to 95%, we might use:<br> - <br> - <a href="printcal.html">printcal</a> <a - href="printcal.html#v">-v</a> <a href="printcal.html#p">-p</a> <a - href="printcal.html#i">-i</a> <a href="colprof.html#x">-xc 80</a> - <a href="colprof.html#x">-xk 95</a> <a href="colprof.html#p2">PrinterB_c</a><br> - <br> - <a href="colprof.html#p2"></a> - <h4><a name="PC5"></a>Using a printer calibration</h4> - The resulting calibration curves can be used with the following - other Argyll tools:<br> - <br> +
+ and then used <a href="xicclu.html#g">xicclu</a> to explore the
+ effect of the parameters.<br>
+ <br>
+ For instance, say we have our CMYK .ti3 file <span
+ style="font-weight: bold;">PrinterB.ti3</span>. First we make a
+ preliminary profile called <span style="font-weight: bold;">PrinterBt</span>:<br>
+ <br>
+ copy PrinterB.ti3 PrinterBt.ti3 (Use
+ "cp" on Linux or OSX of course.)<br>
+ <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a>
+ <a href="colprof.html#q">-qm</a> <a href="colprof.html#b">-b</a> <a
+ href="colprof.html#c">-cmt</a> <a href="colprof.html#d">-dpp</a>
+ <a href="colprof.html#p1">PrinterBt</a><br>
+ <br>
+ Then see what the minimum black level down the neutral axis can be.
+ Note that we need to also set any ink limits we've decided on as
+ well (coloprof defaulting to 10% less than the value recorded in the
+ .ti3 file). In this example the test chart has a 300% total ink
+ limit, and we've decided to use 290%:<br>
+ <br>
+ <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a
+ href="xicclu.html#k">-kz</a> <a href="xicclu.html#l">-l290</a> <a
+ href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a
+ href="xicclu.html#p1">PrinterBt.icm</a><br>
+ <br>
+ Which might be a graph something like this:<br>
+ <br>
+ <img alt="Graph of CMYK neutral axis with minimum K"
+ src="Kgraph1.jpg" style="width: 250px; height: 250px;"><br>
+ <br>
+ Note how the minimum black is zero up to 93% of the
+ white->black L* curve, and then jumps up to 87%. This is because
+ we've reached the total ink limit, and K then has to be substituted
+ for CMY, to keep the total under the total ink limit.<br>
+ <br>
+ Then let's see what the maximum black level down the neutral axis
+ can be:<br>
+ <br>
+ <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a
+ href="xicclu.html#k">-kx</a> <a href="xicclu.html#l">-l290</a> <a
+ href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a
+ href="xicclu.html#p1">PrinterBt.icm</a><br>
+ <br>
+ Which might be a graph something like this:<br>
+ <br>
+ <img alt="Graph of CMYK neutral axis with maximum K"
+ src="Kgraph2.jpg" style="width: 250px; height: 250px;"><br>
+ <br>
+ Note how the CMY values are fairly low up to 93% of the
+ white->black L* curve (the low levels of CMY are helping set the
+ neutral color), and then they jump up. This is because we've reach
+ the point where black on it's own, isn't as dark as the color that
+ can be achieved using CMY and K. Because the K has a dominant effect
+ on the hue of the black, the levels of CMY are often fairly volatile
+ in this region.<br>
+ <br>
+ Any K curve we specify must lie between the black curves of the
+ above two graphs.<br>
+ <br>
+ Let's say we'd like to chose a moderate black curve, one that aims
+ for about equal levels of CMY and K. We should also aim for it to be
+ fairly smooth, since this will minimize visual artefacts caused by
+ the limited fidelity that profile LUT tables are able to represent
+ inside the profile.<br>
+ <br>
+ <img style="width: 340px; height: 258px;" alt="-k parameters"
+ src="Kparams.jpg"><br>
+ <br>
+ <br>
+ For minimum discontinuities we should aim for the curve to finish at
+ the point it has to reach to satisfy the total ink limit at 87%
+ curve and 93% black. For a first try we can simply set a straight
+ line to that point: <br>
+ <br>
+ <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a
+ href="xicclu.html#k">-kp 0 0 .93 .87 1.0</a> <a
+ href="xicclu.html#l">-l290</a> <a href="xicclu.html#f">-fif</a> <a
+ href="xicclu.html#i">-ir</a> <a href="xicclu.html#p1">PrinterBt.icm</a><br>
+ <br>
+ <img alt="Graph of CMYK neutral axis with kp 0 0 1.0 1.0 1.0 -l290"
+ src="Kgraph3.jpg" style="width: 250px; height: 250px;"><br>
+ <br>
+ The black "curve" hits the 93%/87% mark well, but is a bit too far
+ above CMY, so we'll try making the black curve concave:<br>
+ <br>
+ <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a
+ href="xicclu.html#k">-kp </a><a href="xicclu.html#k">0 0 .93 .87
+ 0.65</a> <a href="xicclu.html#l">-l290</a> <a
+ href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a
+ href="xicclu.html#p1">PrinterBt.icm</a><br>
+ <br>
+ <img alt="Graph of CMYK neutral axis with -kp 0 .05 1 .9 1 -l290"
+ src="Kgraph4.jpg" style="width: 250px; height: 249px;"><br>
+ <br>
+ This looks just about perfect, so the the curve parameters can now
+ be used to generate our real profile:<br>
+ <br>
+ <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a>
+ <a href="colprof.html#E">-D"Printer B"</a> <a href="colprof.html#q">-qm</a>
+ <a href="colprof.html#k">-kp </a><a href="xicclu.html#k">0 0 .93
+ .87 0.65</a> <a href="colprof.html#S">-S</a><a
+ href="colprof.html#S"> sRGB.icm</a> <a href="colprof.html#c">-cmt</a>
+ <a href="colprof.html#d">-dpp</a> <a href="colprof.html#p1">PrinterB</a><br>
+ <br>
+ and the resulting B2A table black curve can be checked using xicclu:<br>
+ <br>
+ <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a
+ href="xicclu.html#f">-fb</a> <a href="xicclu.html#i">-ir</a> <a
+ href="xicclu.html#p1">PrinterB.icm</a><br>
+ <br>
+ <img style="width: 250px; height: 250px;" alt="sadsadas"
+ src="Kgraph5.jpg"><br>
+ <br>
+ <br>
+ <hr style="margin-left: 0px; margin-right: auto; width: 20%; height:
+ 2px;"><br>
+ <span style="font-weight: bold;">Examples of other inkings:<br>
+ <br>
+ </span>A smoothed zero black inking:<br>
+ <br>
+ <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a
+ href="xicclu.html#k">-kp </a><a href="xicclu.html#k">0 .7 .93 .87
+ 1.0</a> <a href="xicclu.html#l">-l290</a> <a
+ href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a
+ href="xicclu.html#p1">PrinterBt.icm</a><br>
+ <br>
+ <img style="width: 250px; height: 250px;" alt="sadsadas"
+ src="Kgraph6.jpg"><br>
+ <br>
+ A low black inking:<br>
+ <br>
+ <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a
+ href="xicclu.html#k">-kp </a><a href="xicclu.html#k">0 0 .93 .87
+ 0.15</a> <a href="xicclu.html#l">-l290</a> <a
+ href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a
+ href="xicclu.html#p1">PrinterBt.icm</a><br>
+ <br>
+ <img style="width: 250px; height: 250px;" alt="sadsadas"
+ src="Kgraph7.jpg"><br>
+ <br>
+ <br>
+ A high black inking:<br>
+ <br>
+ <a href="xicclu.html">xicclu</a> <a href="xicclu.html#g">-g</a> <a
+ href="xicclu.html#k">-kp </a><a href="xicclu.html#k">0 0 .93 .87
+ 1.2</a> <a href="xicclu.html#l">-l290</a> <a
+ href="xicclu.html#f">-fif</a> <a href="xicclu.html#i">-ir</a> <a
+ href="xicclu.html#p1">PrinterBt.icm</a><br>
+ <br>
+ <img style="width: 250px; height: 250px;" alt="sadsadas"
+ src="Kgraph8.jpg"><br>
+ <br>
+ <span style="font-weight: bold;"></span>
+ <h4>Overriding the ink limit<br>
+ </h4>
+ Normally the total ink limit will be read from the <span
+ style="font-weight: bold;">PrinterB.ti3</span> file, and will be
+ set at a level 10% lower than the number used in creating the test
+ chart values using <a href="targen.html#l">targen -l</a>. If you
+ want to override this with a lower limit, then use the <a
+ href="colprof.html#l">-l flag</a>.<br>
+ <br>
+ <a href="colprof.html">colprof</a> <a href="colprof.html#v">-v</a>
+ <a href="colprof.html#E">-D"Printer B"</a> <a href="colprof.html#q">-qm</a>
+ <a href="colprof.html#S">-S</a><a href="colprof.html#S"> sRGB.icm</a>
+ <a href="colprof.html#c">-cmt</a> <a href="colprof.html#d">-dpp</a>
+ <a href="colprof.html#k">-kr</a> <a href="xicclu.html#l">-l290</a>
+ <a href="colprof.html#p1">PrinterB</a><br>
+ <br>
+ Make sure you check the delta E report at the end of the profile
+ creation, to see if the profile is behaving reasonably.<br>
+ <br>
+ One way of checking that your ink limit is not too high, is to use "<span
+ style="font-weight: bold;">xicc -fif -ia</span>" to check, by
+ setting different ink limits using the <span style="font-weight:
+ bold;">-l</span> option, feeding Lab = 0 0 0 into it, and checking
+ the resulting black point. Starting with the ink limit used
+ with <span style="font-weight: bold;">targen</span> for the test
+ chart, reduce it until the black point starts to be affected. If it
+ is immediately affected by any reduction in the ink limit, then the
+ black point may be improved by increasing the ink limit used to
+ generate the test chart and then re-print and re-measuring it,
+ assuming other aspects such as wetness, smudging, spreading or
+ drying time are not an issue.<br>
+ <br>
+ <hr style="width: 100%; height: 2px;"><br>
+ <h3><a name="PC1"></a>Calibrating Printers<br>
+ </h3>
+ <span style="font-weight: bold;">Profiling</span> creates a
+ description of how a device behaves, while <span
+ style="font-weight: bold;">calibration</span> on the other hand is
+ intended to <span style="text-decoration: underline;">change</span>
+ how a device behaves. Argyll has the ability to create per-channel
+ device space calibration curves for print devices, that can then be
+ used to improve the behavior of of the device, making a subsequent
+ profile fit the device more easily and also allow day to day
+ correction of device drift without resorting to a full re-profile.<br>
+ <br>
+ <span style="font-weight: bold;">NOTE:</span> Because calibration
+ adds yet another layer to the way color is processed, it is
+ recommended that it not be attempted until the normal profiling
+ workflow is established, understood and verified.<br>
+ <h4><a name="PC2"></a>Calibrated print workflows</h4>
+ There are two main workflows that printer calibration curves can be
+ applied to:<br>
+ <br>
+ <span style="text-decoration: underline;">Workflow <span
+ style="font-weight: bold;">with</span> native calibration
+ capability</span>:<br>
+ <br>
+ Firstly the printer itself may have the capability of using per
+ channel calibration curves. In this situation, the calibration
+ process will be largely independent of profiling. Firstly the
+ printer is configured to have both its color management and
+ calibration disabled (the latter perhaps achieved by loading linear
+ calibration curves), and a print calibration test chart that
+ consists of per channel color wedges is printed. The calibration
+ chart is read and the resulting .ti3 file converted into calibration
+ curves by processing it using <span style="font-weight: bold;">printcal</span>.
+ The calibration is then installed into the printer. Subsequent
+ profiling will be performed on the <span style="text-decoration:
+ underline;">calibrated</span> printer (ie. the profile test chart
+ will have the calibration curves applied to it by the printer, and
+ the resulting ICC profile will represent the behavior of the
+ calibrated printer.)<br>
+ <br>
+ <span style="text-decoration: underline;">Workflow <span
+ style="font-weight: bold;">without</span> native calibration
+ capability</span>:<br>
+ <br>
+ The second workflow is one in which the printer has no calibration
+ capability itself. In this situation, the calibration process will
+ have to be applied using the ICC color management tools, so careful
+ coordination with profiling is needed. Firstly the printer is
+ configured to have its color management disabled, and a print
+ calibration test chart that consists of per channel color wedges is
+ printed. The calibration chart is converted into calibration curves
+ by reading it and then processing the resultant .ti3 using <span
+ style="font-weight: bold;">printcal</span>,. During the subsequent
+ <span style="text-decoration: underline;">profiling</span>, the
+ calibration curves will need to be applied to the profile test chart
+ in the process of using <span style="font-weight: bold;">printtarg</span>.
+ Once the the profile has been created, then in subsequent printing
+ the calibration curves will need to be applied to an image being
+ printed either explicitly when using <span style="font-weight:
+ bold;">cctiff</span> to apply color profiles <span
+ style="text-decoration: underline;">and</span> calibration, <span
+ style="font-weight: bold;">OR</span> by creating a version of the
+ profile that has had the calibration curves incorporated into it
+ using the <span style="font-weight: bold;">applycal</span> tool.
+ The latter is useful when some CMM (color management module) other
+ than <span style="font-weight: bold;">cctiff </span>is being used.<br>
+ <br>
+ Once calibration aim targets for a particular device and mode
+ (screening, paper etc.) have been established, then the printer can
+ be re-calibrated at any time to bring its per channel behavior back
+ into line if it drifts, and the new calibration curves can be
+ installed into the printer, or re-incorporated into the profile.
+
+ <h4><a name="PC3"></a>Creating a print calibration test chart</h4>
+ The first step is to create a print calibration test chart. Since
+ calibration only creates per-channel curves, only single channel
+ step wedges are required for the chart. The main choice is the
+ number of steps in each wedge. For simple fast calibrations perhaps
+ as few as 20 steps per channel may be enough, but for a better
+ quality of calibration something like 50 or more steps would be a
+ better choice.<br>
+ <br>
+ Let's consider two devices in our examples, "PrinterA" which is an
+ "RGB" printer device, and "PrinterB" which is CMYK. In fact there is
+ no such thing as a real RGB printer, since printers use white media
+ and the colorant must subtract from the light reflected on it to
+ create color, but the printer itself turns the incoming RGB into the
+ native print colorspace, so for this reason we are careful to tell
+ targen to use the "Print RGB" colorspace, so that it knows to create
+ step wedges from media white to full colorant values.<br>
+ <br>
+ For instance, to create a 50 steps per channel calibration test
+ chart for our RGB and CMYK devices, the following would be
+ sufficient:<br>
+ <br>
+ <a href="targen.html">targen</a> <a href="targen.html#v">-v</a>
+ <a href="targen.html#d">-d2</a> <a href="targen.html#s">-s50</a>
+ <a href="targen.html#e">-e3</a> <a href="targen.html#f">-f0</a> <a
+ href="targen.html#p1">PrinterA_c</a><br>
+ <br>
+ <a href="targen.html">targen</a> <a href="targen.html#v">-v</a>
+ <a href="targen.html#d">-d4</a> <a href="targen.html#s">-s50</a>
+ <a href="targen.html#e">-e4</a> <a href="targen.html#f">-f0</a> <a
+ href="targen.html#p1">PrinterB_c</a><br>
+ <a href="targen.html#p1"></a><br>
+ For an outline of how to then print and read the resulting test
+ chart, see <a href="Scenarios.html#PP2b">Printing a print
+ profile test chart</a>, and <a href="Scenarios.html#PP3">Reading
+ a print test chart using an instrument</a>. Note that the printer
+ must be in an un-profiled and un-calibrated mode when doing this
+ print. Having done this, there will be a PrinterA.ti3 or
+ PrinterB.ti3 file containing the step wedge calibration chart
+ readings.<br>
+ <br>
+ <span style="font-weight: bold;">NOTE</span> that if you are
+ calibrating a raw printer driver, and there is considerable dot
+ gain, then you may want to use the <a href="targen.html#p">-p</a>
+ parameter to adjust the test chart point distribution to spread them
+ more evenly in perceptual space, giving more accurate control over
+ the calibration. Typically this will be a value greater than one for
+ a device that has dot gain, e.g. values of 1.5, 2.0 or 2.5 might be
+ good places to start. You can do a preliminary calibration and use
+ the verbose output of printcal to recommend a suitable value for <span
+ style="font-weight: bold;">-p</span>.<br>
+ <h4><a name="PC4"></a>Creating a printer calibration<br>
+ </h4>
+ The <a href="printcal.html">printcal</a> tool turns a calibration
+ chart <a href="File_Formats.html#.ti3">.ti3</a> file into a <a
+ href="File_Formats.html#.cal">.cal</a> file. It has three main
+ operating modes:- Initial calibration, Re-Calibration, and
+ Verification. (A fourth mode, "Imitation" is very like Initial
+ Calibration, but is used for establishing a calibration target that
+ a similar printer can attempt to imitate.)<br>
+ <br>
+ The distinction between Initial Calibration and Re-Calibration is
+ that in the initial calibration we establish the "aim points" or
+ response we want out of the printer after calibration. There are
+ three basic parameters to set this for each channel: Maximum level,
+ minimum level, and curve shape.<br>
+ <br>
+ By default the maximum level will be set using a heuristic which
+ attempts to pick the point when there is diminishing returns for
+ applying more colorant. This can be overridden using the <span
+ style="font-weight: bold;">-x# percent</span> option, where <span
+ style="font-weight: bold;">#</span> represents the choice of
+ channel this will be applied to. The parameter is the percentage of
+ device maximum. <br>
+ <br>
+ The minimum level defaults to 0, but can be overridden using the <span
+ style="font-weight: bold;">-n# deltaE</span> option. A minimum of
+ 0 means that zero colorant will correspond to the natural media
+ color, but it may be desirable to set a non-pure media color using
+ calibration for the purposes of emulating some other media. The
+ parameter is in Delta E units.<br>
+ <br>
+ The curve shape defaults to being perceptually uniform, which means
+ that even steps of calibrated device value result in perceptually
+ even color steps. In some situations it may be desirable to alter
+ this curve (for instance when non color managed output needs to be
+ sent to the calibrated printer), and a simple curve shape target can
+ be set using the <span style="font-weight: bold;">-t# percent</span>
+ parameter. This affects the output value at 50% input value, and
+ represents the percentage of perceptual output. By default it is 50%
+ perceptual output for 50% device input.<br>
+ <br>
+ Once a device has been calibrated, it can be re-calibrated to the
+ same aim target.<br>
+ <br>
+ Verification uses a calibration test chart printed through the
+ calibration, and compares the achieved response to the aim target.<br>
+ <br>
+ The simplest possible way of creating the <span style="font-weight:
+ bold;">PrinterA.cal</span> file is:<br>
+ <br>
+ <a href="printcal.html">printcal</a> <a
+ href="printcal.html#i">-i</a> <a href="colprof.html#p2">PrinterA_c</a><br>
+ <br>
+ For more detailed information, you can add the <span
+ style="font-weight: bold;">-v</span> and <span
+ style="font-weight: bold;">-p</span> flags:<br>
+ <br>
+ <a href="printcal.html">printcal</a> <a
+ href="printcal.html#v">-v</a> <a href="printcal.html#p">-p</a> <a
+ href="printcal.html#i">-i</a> <a href="colprof.html#p2">PrinterB_c</a><br>
+ <br>
+ (You will need to select the plot window and hit a key to advance
+ past each plot).<br>
+ <br>
+ For re-calibration, the name of the previous calibration file will
+ need to be supplied, and a new calibration<br>
+ file will be created:<br>
+ <br>
+ <a href="printcal.html">printcal</a> <a
+ href="printcal.html#v">-v</a> <a href="printcal.html#p">-p</a> <a
+ href="printcal.html#r">-r</a> <a href="colprof.html#p1">PrinterB_c_old</a>
+ <a href="colprof.html#p2">PrinterB_c_new</a><br>
+ <br>
+ Various aim points are normally set automatically by <span
+ style="font-weight: bold;">printcal</span>, but these can be
+ overridden using the <a href="colprof.html#x">-x</a>, <a
+ href="colprof.html#n">-n</a> and <a href="colprof.html#t">-t</a>
+ options. e.g. say we wanted to set the maximum ink for Cyan to 80%
+ and Black to 95%, we might use:<br>
+ <br>
+ <a href="printcal.html">printcal</a> <a
+ href="printcal.html#v">-v</a> <a href="printcal.html#p">-p</a> <a
+ href="printcal.html#i">-i</a> <a href="colprof.html#x">-xc 80</a>
+ <a href="colprof.html#x">-xk 95</a> <a href="colprof.html#p2">PrinterB_c</a><br>
+ <br>
+ <a href="colprof.html#p2"></a>
+ <h4><a name="PC5"></a>Using a printer calibration</h4>
+ The resulting calibration curves can be used with the following
+ other Argyll tools:<br>
+ <br>
<a href="printtarg.html#K">printtarg</a> To apply @@ -2661,10 +2617,8 @@ chart, - - - - and/or to have it included in .ti3 file.<br> +
+ and/or to have it included in .ti3 file.<br>
<a href="cctiff.html#p2">cctiff</a> To apply @@ -2730,10 +2684,8 @@ an - - - - image file.<br> +
+ image file.<br>
<a href="applycal.html#p1">applycal</a> @@ -2791,10 +2743,8 @@ an - - - - To incorporate calibration into an ICC profile.<br> +
+ To incorporate calibration into an ICC profile.<br>
<a href="chartread.html#I">chartread</a> To override @@ -2860,405 +2810,396 @@ a - - - - profile chart.<br> - <br> - <br> - In a workflow <span style="font-weight: bold;">with</span> native - calibration capability, the calibration curves would be used with - printarg during subsequent <span style="font-weight: bold;">profiling</span> - so that any ink limit calculations will reflect final device values, - while not otherwise using the calibration within the ICC workflow:<br> - <br> - <a href="printtarg.html">printtarg</a> <a - href="printtarg.html#v">-v</a> <a href="printtarg.html#i">-ii1</a> - <a href="printtarg.html#p">-pA4</a> <a href="printtarg.html#I">-I - PrinterA_c.cal</a> <a href="printtarg.html#p1">PrinterA</a><br> - <br> - This will cause the .ti2 and resulting .ti3 and ICC profiles to - contain the calibration curves, allowing all the tools to be able to - compute final device value ink limits. The calibration curves must - also of course be installed into the printer. The means to do this - is currently outside the scope of Argyll (ie. either the print - system needs to be able to understand Argyll CAL format files, or - some tool will be needed to convert Argyll CAL files into the - printer calibration format).<br> - <br> - <br> - In a workflow <span style="font-weight: bold;">without</span> - native calibration capability, the calibration curves would be used - with printarg to <span style="text-decoration: underline;">apply</span> - the calibration to the test patch samples during subsequent <span - style="font-weight: bold;">profiling</span>, as well as embedding - it in the resulting .ti3 to allow all the tools to be able to - compute final device value ink limits:<br> - <br> - <a href="printtarg.html">printtarg</a> <a - href="printtarg.html#v">-v</a> <a href="printtarg.html#i">-ii1</a> - <a href="printtarg.html#p">-pA4</a> <a href="printtarg.html#K">-K - PrinterA_c.cal</a> <a href="printtarg.html#p1">PrinterA</a><br> - <a href="cctiff.html#p4"></a><br> - To apply calibration to an ICC profile, so that a calibration - unaware CMM can be used:<br> - <br> - <a href="applycal.html">applycal</a> <a - href="applycal.html#p1">PrinterA.cal</a> <a - href="applycal.html#p2">PrinterA.icm</a> <a - href="applycal.html#p3">PrinterA_cal.icm</a><br> - <br> - To apply color management and calibration to a raster image:<br> - <br> - <a href="cctiff.html">cctiff</a> - <a href="cctiff.html#p1">Source.icm</a> <a - href="cctiff.html#p1">PrinterA.icm</a> <a - href="cctiff.html#p2">PrinterA_c.cal</a> - <a href="cctiff.html#p3">infile.tif</a> <a - href="cctiff.html#p4">outfile.tif</a><br> - <br> - or<br> - <br> - <a href="cctiff.html">cctiff</a> - <a href="cctiff.html#p1">Source.icm</a> <a - href="cctiff.html#p1">PrinterA_c.icm</a> - <a href="cctiff.html#p3">infile.tif</a> <a - href="cctiff.html#p4">outfile.tif</a><br> - <br> - [ Note that cctiff will also process JPEG raster images. ]<br> - <br> - Another useful tool is <a href="synthcal.html">synthcal</a>, that - allows creating linear or synthetic calibration files for disabling - calibration or testing.<br> - Similarly, <a href="fakeread.html">fakeread</a> also supports - applying calibration curves and embedding them in the resulting .ti3 - file<br> - <br> - If you want to create a pre-conditioning profile for use with <a - href="targen.html#c">targen -c</a>, then use the PrinterA.icm - profile, <b>NOT</b> PrinterA_c.icm that has calibration curves - applied.<br> - <h4><a name="PC6"></a>How profile ink limits are handled when - calibration is being used.</h4> - Even though the profiling process is carried out on top of the - linearized device, and the profiling is generally unaware of the - underlying non-linearized device values, an exception is made in the - calculation of ink limits during profiling. This is made possible by - including the calibration curves in the profile charts .ti2 and - subsequent .ti3 file and resulting ICC profile <span - style="font-weight: bold;">'targ'</span> text tag, by way of the <span - style="font-weight: bold;">printtarg</span> <span - style="font-weight: bold;">-I</span> or <span style="font-weight: - bold;">-K</span> options. This is done on the assumption that the - physical quantity of ink is what's important in setting the ink - limit, and that the underlying non-linearized device values - represent such a physical quantity.<br> - <br> - <br> - <hr size="2" width="100%"> - <h3><a name="LP1"></a>Linking Profiles</h3> - Two device profiles can be linked together to create a device link - profile, than encapsulates a particular device to device transform. - Often this step is not necessary, as many systems and tools will - link two device profiles "on the fly", but creating a device link - profile gives you the option of using "smart CMM" techniques, such - as true gamut mapping, improved inverse transform accuracy, tailored - black generation and ink limiting.<br> - <br> - The overall process is to link the input space and output space - profiles using <a href="collink.html">collink</a>, creating a - device to device link profile. The device to device link profile can - then be used by cctiff (or other ICC device profile capable tools), - to color correct a raster files.<br> - <br> - Three examples will be given here, showing the three different modes - than <span style="font-weight: bold;">collink</span> supports.<br> - <br> - In <a href="collink.html#s">simple mode</a>, the two profiles are - linked together in a similar fashion to other <span - style="font-weight: bold;">CMMs</span> simply using the forward - and backwards color transforms defined by the profiles. Any gamut - mapping is determined by the content of the tables within the two - profiles, together with the particular intent chosen. Typically the - same intent will be used for both the source and destination - profile:<br> - <br> - <a href="collink.html">collink</a> <a href="collink.html#v">-v</a> - <a href="collink.html#q">-qm</a> <a href="collink.html#s">-s</a> <a - href="collink.html#si">-ip</a> <a href="collink.html#so">-op</a> - <a href="collink.html#p1">SouceProfile.icm</a> <a - href="collink.html#p2">DestinationProfile.icm</a> <a - href="collink.html#p3">Source2Destination.icm</a><br> - <br> - <br> - In <a href="collink.html#g">gamut mapping mode</a>, the - pre-computed intent mappings inside the profiles are not used, but - instead the gamut mapping between source and destination is tailored - to the specific gamuts of the two profiles, and the intent parameter - supplied to <span style="font-weight: bold;">collink</span>. - Additionally, source and destination viewing conditions should be - provided, to allow the color appearance space conversion to work as - intended. The colorimetric B2A table in the destination profile is - used, and this will determine any black generation and ink limiting:<br> - <br> - <a href="collink.html">collink</a> <a href="collink.html#v">-v</a> - <a href="collink.html#q">-qm</a> <a href="collink.html#g">-g</a> <a - href="collink.html#si">-ip</a> <a href="collink.html#c">-cmt</a> - <a href="collink.html#d">-dpp</a> <a href="collink.html#p1">MonitorSouceProfile.icm</a> - <a href="collink.html#p2">DestinationProfile.icm</a> <a - href="collink.html#p3">Source2Destination.icm</a><br> - <br> - [ If your viewing environment for the display and print doesn't - match the ones implied by the <a href="colprof.html#c">-cmt</a> and - <a href="colprof.html#d">-dpp</a> options, leave them out, and - evaluate what, if any appearance transformation is appropriate for - your environment at a later stage. ]<br> - <br> - In <a href="collink.html#G">inverse output table gamut mapping mode</a>, - the pre-computed intent mappings inside the profiles are not used, - but instead the gamut mapping between source and destination is - tailored to the specific gamuts of the two profiles, and the intent - parameter supplied to <span style="font-weight: bold;">collink</span>. - In addition, the B2A table is <span style="font-weight: bold;">not</span> - used in the destination profile, but the A2B table is instead - inverted, leading to improved transform accuracy, and in CMYK - devices, allowing the ink limiting and black generation parameters - to be set:<br> - <br> - For a CLUT table based RGB printer destination profile, the - following would be appropriate:<br> - <br> - <a href="collink.html">collink</a> <a href="collink.html#v">-v</a> - <a href="collink.html#q">-qm</a> <a href="collink.html#G">-G</a> <a - href="collink.html#si">-ip</a> <a href="collink.html#c">-cmt</a> - <a href="collink.html#d">-dpp</a> <a href="collink.html#p1">MonitorSouceProfile.icm</a> - <a href="collink.html#p2">RGBDestinationProfile.icm</a> <a - href="collink.html#p3">Source2Destination.icm</a><br> - <br> - For a CMYK profile, the total ink limit needs to be specified (a - typical value being 10% less than the value used in creating the - device test chart), and the type of black generation also needs to - be specified:<br> - <br> - <a href="collink.html">collink</a> <a href="collink.html#v">-v</a> - <a href="collink.html#q">-qm</a> <a href="collink.html#G">-G</a> <a - href="collink.html#si">-ip</a> <a href="collink.html#c">-cmt</a> - <a href="collink.html#d">-dpp</a> <a href="collink.html#l">-l250</a> - <a href="collink.html#k">-kr</a> <a href="collink.html#p1">MonitorSouceProfile.icm</a> - <a href="collink.html#p2">CMYKDestinationProfile.icm</a> <a - href="collink.html#p3">Source2Destination.icm</a><br> - <br> - Note that you should set the source (<a href="collink.html#c">-c</a>) - and destination (<a href="collink.html#d">-d</a>) viewing conditions - for the type of device the profile represents, and the conditions - under which it will be viewed.<br> - <br> - <h3><a name="LP3"></a>Image dependent gamut mapping using device - links<br> - </h3> - When images are stored in large gamut colorspaces (such as. L*a*b*, - ProPhoto, scRGB etc.), then using the colorspace gamut as the source - gamut for gamut mapping is generally a bad idea, as it leads to - overly compressed and dull images. The correct approach is to use a - source gamut that represents the gamut of the images themselves. - This can be created using tiffgamut, and an example workflow is as - follows:<br> - <br> - <a href="tiffgamut.html">tiffgamut</a> -f80 -pj -cmt ProPhoto.icm - image.tif<br> - <br> - <a href="collink.html">collink</a> <a href="collink.html#v">-v</a> - <a href="collink.html#q">-qh</a> <a href="collink.html#G">-G</a> <a - href="collink.html#Gp">image.gam</a> <a href="collink.html#si">-ip</a> - <a href="collink.html#c">-cmt</a> <a href="collink.html#d">-dpp</a> - <a href="collink.html#p1">ProPhoto.icm</a> <a - href="collink.html#p2">RGBDestinationProfile.icm</a> - <a href="collink.html#p3">Source2Destination.icm</a><br> - <br> - <a href="cctiff.html">cctiff</a> <a - href="cctiff.html#p1">Source2Destination.icm</a> - <a href="cctiff.html#p3">image.tif</a> <a - href="cctiff.html#p4">printfile.tif</a><br> - <br> - The printfile.tif is then send to the printer without color - management, (i.e. in the same way the printer characterization test - chart was printed), since it is in the printers native colorspace.<br> - <br> - You can adjust how conservatively the image gamut is preserved using - the tiffgamut -f parameter. Omitting it or using a larger value (up - to 100) preserves the color gradations of even the lesser used - colors, at the cost of compressing the gamut more.<br> - Using a smaller value will preserve the saturation of the most - popular colors, at the cost of not preserving the color gradations - of less popular colors.<br> - <br> - You can create a gamut that covers a set of source images by - providing more than one image file name to tiffgamut. This may be - more efficient for a group of related images, and ensures that - colors are transformed in exactly the same way for all of the - images.<br> - <br> - An alternative generating a gamut for a specific set of images, is - to use a general smaller gamut definition (i.e. the sRGB profile), - or a gamut that represents the typical range of colors you wish to - preserve.<br> - <br> - The arguments to collink should be appropriate for the output device - type - see the collink examples in the above section.<br> - <h3><a name="LP2"></a>Soft Proofing Link</h3> - Often it is desirable to get an idea what a particular devices - output will look like using a different device. Typically this might - be trying to evaluate print output using a display. Often it is - sufficient to use an absolute or relative colorimetric transform - from the print device space to the display space, but while these - provide a colorimetric preview of the result, they do not take into - account the subjective appearance differences due to the different - device conditions. It can therefore be useful to create a soft proof - appearance transform using collink:<br> - <br> - <a href="collink.html">collink</a> <a href="collink.html#v">-v</a> - <a href="collink.html#q">-qm</a> <a href="collink.html#G">-G</a> <a - href="collink.html#si">-ila</a> <a href="collink.html#c">-cpp</a> - <a href="collink.html#d">-dmt</a> <a href="collink.html#l">-t250</a> <a - href="collink.html#k"></a><a href="collink.html#p1">CMYKDestinationProfile.icm</a> - <a href="collink.html#p2">MonitorProfile.icm</a> <a - href="collink.html#p3">SoftProof.icm</a><br> - <br> - We use the Luminance matched appearance intent, to preserve the - subjective apperance of the target device, which takes into account - the viewing conditions and assumes adaptation to the differences in - the luminence range, but otherwise not attempting to compress or - change the gamut.<br> - <br> - If your viewing environment for the display and print doesn't match - the ones implied by the <a href="collink.html#c">-cpp</a> and <a - href="collink.html#d">-dmt</a> options, then either leave them out - or substitute values that do match your environment.<br> - - <hr size="2" width="100%"><br> - <h3><a name="TR1"></a>Transforming colorspaces of raster files</h3> - Although a device profile or device link profile may be useful with - other programs and systems, Argyll provides the tool <a - href="cctiff.html">cctiff</a> for directly applying a device to - device transform to a <a href="File_Formats.html#TIFF">TIFF</a> or - <a href="File_Formats.html#JPEG">JPEG</a> raster file. The cctiff - tool is capable of linking an arbitrary sequence of device profiles, - device links, abstract profiles and calibration curves. Each device - profile can be preceded by the <span style="font-weight: bold;">-i</span> - option to indicate the intent that should be used. Both 8 and 16 bit - per component files can be handled, and up to 8 color channels. The - color transform is optimized to perform the overall transformation - rapidly.<br> - <br> - If a device link is to be used, the following is a typical example:<br> - <br> - <a href="cctiff.html">cctiff</a> <a href="cctiff.html#p1">Source2Destination.icm</a> - <a href="cctiff.html#p3">infile.tif</a> <a href="cctiff.html#p4">outfile.tif</a><br> - or<br> - <a href="cctiff.html">cctiff</a> <a href="cctiff.html#p1">Source2Destination.icm</a> - <a href="cctiff.html#p3">infile.jpg</a> <a href="cctiff.html#p4">outfile.jpg</a><br> - <br> - <i><br> - </i>If a source and destination profile are to be used, the - following would be a typical example:<br> - <br> - <a href="cctiff.html"> cctiff</a> <a href="cctiff.html#i">-ip</a> - <a href="cctiff.html#p1i">SourceProfile.icm</a> <a - href="cctiff.html#i">-ip</a> <a href="cctiff.html#p1o">DestinationProfile.icm</a> - <a href="cctiff.html#p3">infile.tif</a> <a href="cctiff.html#p4">outfile.tif</a><br> - or<br> - <a href="cctiff.html"> cctiff</a> <a href="cctiff.html#i">-ip</a> - <a href="cctiff.html#p1i">SourceProfile.icm</a> <a - href="cctiff.html#i">-ip</a> <a href="cctiff.html#p1o">DestinationProfile.icm</a> - <a href="cctiff.html#p3">infile.jpg</a> <a href="cctiff.html#p4">outfile.jpg</a><br> - <br> - <br> - <hr size="2" width="100%"><br> - <h3><a name="TV1"></a>Creating Video Calibration 3DLuts</h3> - Video calibration typically involves trying to make your actual - display device emulate an ideal video display, one which matches - what your Video media was intended to be displayed on. An ICC device - link embodies the machinery to do exactly this, to take device - values in the target source colorspace and transform them into an - actual output device colorspace. In the Video and Film industries a - very similar, but less sophisticated means of doing this is to use - 3DLuts, which come in a multitude of different format. ICC device - links have the advantage of being a superset of 3dLuts, encapsulated - in a standard file format.<br> - <br> - To facilitate Video calibration of certain Video systems, ArgyllCMS - supports some 3DLut output options as part of <a - href="collink.html">collink</a>.<br> - <br> - What follows here is an outline of how to create Video calibration - 3DLuts using ArgyllCMS. First comes a general discussion of various - aspects of video device links/3dLuts, and followed with some - specific advice regarding the systems that ArgyllCMS supports. Last - is some recommended scenarios for verifying the quality of Video - calibration achieved.<br> - <h5>1) How to display test patches.<br> - </h5> - Argyll's normal test patch display will be used by default, as long - as any video encoding range considerations are dealt with (see - Signal encoding below).<br> - <br> - An alternative when working with MadVR V 0.86.9 or latter, is to use - the madTPG to display the patches in which case the MadVR video - encoding range setting will operate. This can give some quality - benefits due to MadVR's use of dithering. To display patches using +
+ profile chart.<br>
+ <br>
+ <br>
+ In a workflow <span style="font-weight: bold;">with</span> native
+ calibration capability, the calibration curves would be used with
+ printarg during subsequent <span style="font-weight: bold;">profiling</span>
+ so that any ink limit calculations will reflect final device values,
+ while not otherwise using the calibration within the ICC workflow:<br>
+ <br>
+ <a href="printtarg.html">printtarg</a> <a
+ href="printtarg.html#v">-v</a> <a href="printtarg.html#i">-ii1</a>
+ <a href="printtarg.html#p">-pA4</a> <a href="printtarg.html#I">-I
+ PrinterA_c.cal</a> <a href="printtarg.html#p1">PrinterA</a><br>
+ <br>
+ This will cause the .ti2 and resulting .ti3 and ICC profiles to
+ contain the calibration curves, allowing all the tools to be able to
+ compute final device value ink limits. The calibration curves must
+ also of course be installed into the printer. The means to do this
+ is currently outside the scope of Argyll (ie. either the print
+ system needs to be able to understand Argyll CAL format files, or
+ some tool will be needed to convert Argyll CAL files into the
+ printer calibration format).<br>
+ <br>
+ <br>
+ In a workflow <span style="font-weight: bold;">without</span>
+ native calibration capability, the calibration curves would be used
+ with printarg to <span style="text-decoration: underline;">apply</span>
+ the calibration to the test patch samples during subsequent <span
+ style="font-weight: bold;">profiling</span>, as well as embedding
+ it in the resulting .ti3 to allow all the tools to be able to
+ compute final device value ink limits:<br>
+ <br>
+ <a href="printtarg.html">printtarg</a> <a
+ href="printtarg.html#v">-v</a> <a href="printtarg.html#i">-ii1</a>
+ <a href="printtarg.html#p">-pA4</a> <a href="printtarg.html#K">-K
+ PrinterA_c.cal</a> <a href="printtarg.html#p1">PrinterA</a><br>
+ <a href="cctiff.html#p4"></a><br>
+ To apply calibration to an ICC profile, so that a calibration
+ unaware CMM can be used:<br>
+ <br>
+ <a href="applycal.html">applycal</a> <a
+ href="applycal.html#p1">PrinterA.cal</a> <a
+ href="applycal.html#p2">PrinterA.icm</a> <a
+ href="applycal.html#p3">PrinterA_cal.icm</a><br>
+ <br>
+ To apply color management and calibration to a raster image:<br>
+ <br>
+ <a href="file:///D:/src/argyll/doc/cctiff.html">cctiff</a>
+ <a href="file:///D:/src/argyll/doc/cctiff.html#p1">Source.icm</a> <a
+ href="file:///D:/src/argyll/doc/cctiff.html#p1">PrinterA.icm</a> <a
+ href="file:///D:/src/argyll/doc/cctiff.html#p2">PrinterA_c.cal</a>
+ <a href="file:///D:/src/argyll/doc/cctiff.html#p3">infile.tif</a> <a
+ href="file:///D:/src/argyll/doc/cctiff.html#p4">outfile.tif</a><br>
+ <br>
+ or<br>
+ <br>
+ <a href="file:///D:/src/argyll/doc/cctiff.html">cctiff</a>
+ <a href="file:///D:/src/argyll/doc/cctiff.html#p1">Source.icm</a> <a
+ href="file:///D:/src/argyll/doc/cctiff.html#p1">PrinterA_c.icm</a>
+ <a href="file:///D:/src/argyll/doc/cctiff.html#p3">infile.tif</a> <a
+ href="file:///D:/src/argyll/doc/cctiff.html#p4">outfile.tif</a><br>
+ <br>
+ [ Note that cctiff will also process JPEG raster images. ]<br>
+ <br>
+ Another useful tool is <a href="synthcal.html">synthcal</a>, that
+ allows creating linear or synthetic calibration files for disabling
+ calibration or testing.<br>
+ Similarly, <a href="fakeread.html">fakeread</a> also supports
+ applying calibration curves and embedding them in the resulting .ti3
+ file<br>
+ <br>
+ If you want to create a pre-conditioning profile for use with <a
+ href="targen.html#c">targen -c</a>, then use the PrinterA.icm
+ profile, <b>NOT</b> PrinterA_c.icm that has calibration curves
+ applied.<br>
+ <h4><a name="PC6"></a>How profile ink limits are handled when
+ calibration is being used.</h4>
+ Even though the profiling process is carried out on top of the
+ linearized device, and the profiling is generally unaware of the
+ underlying non-linearized device values, an exception is made in the
+ calculation of ink limits during profiling. This is made possible by
+ including the calibration curves in the profile charts .ti2 and
+ subsequent .ti3 file and resulting ICC profile <span
+ style="font-weight: bold;">'targ'</span> text tag, by way of the <span
+ style="font-weight: bold;">printtarg</span> <span
+ style="font-weight: bold;">-I</span> or <span style="font-weight:
+ bold;">-K</span> options. This is done on the assumption that the
+ physical quantity of ink is what's important in setting the ink
+ limit, and that the underlying non-linearized device values
+ represent such a physical quantity.<br>
+ <br>
+ <br>
+ <hr size="2" width="100%">
+ <h3><a name="LP1"></a>Linking Profiles</h3>
+ Two device profiles can be linked together to create a device link
+ profile, than encapsulates a particular device to device transform.
+ Often this step is not necessary, as many systems and tools will
+ link two device profiles "on the fly", but creating a device link
+ profile gives you the option of using "smart CMM" techniques, such
+ as true gamut mapping, improved inverse transform accuracy, tailored
+ black generation and ink limiting.<br>
+ <br>
+ The overall process is to link the input space and output space
+ profiles using <a href="collink.html">collink</a>, creating a
+ device to device link profile. The device to device link profile can
+ then be used by cctiff (or other ICC device profile capable tools),
+ to color correct a raster files.<br>
+ <br>
+ Three examples will be given here, showing the three different modes
+ than <span style="font-weight: bold;">collink</span> supports.<br>
+ <br>
+ In <a href="collink.html#s">simple mode</a>, the two profiles are
+ linked together in a similar fashion to other <span
+ style="font-weight: bold;">CMMs</span> simply using the forward
+ and backwards color transforms defined by the profiles. Any gamut
+ mapping is determined by the content of the tables within the two
+ profiles, together with the particular intent chosen. Typically the
+ same intent will be used for both the source and destination
+ profile:<br>
+ <br>
+ <a href="collink.html">collink</a> <a href="collink.html#v">-v</a>
+ <a href="collink.html#q">-qm</a> <a href="collink.html#s">-s</a> <a
+ href="collink.html#si">-ip</a> <a href="collink.html#so">-op</a>
+ <a href="collink.html#p1">SouceProfile.icm</a> <a
+ href="collink.html#p2">DestinationProfile.icm</a> <a
+ href="collink.html#p3">Source2Destination.icm</a><br>
+ <br>
+ <br>
+ In <a href="collink.html#g">gamut mapping mode</a>, the
+ pre-computed intent mappings inside the profiles are not used, but
+ instead the gamut mapping between source and destination is tailored
+ to the specific gamuts of the two profiles, and the intent parameter
+ supplied to <span style="font-weight: bold;">collink</span>.
+ Additionally, source and destination viewing conditions should be
+ provided, to allow the color appearance space conversion to work as
+ intended. The colorimetric B2A table in the destination profile is
+ used, and this will determine any black generation and ink limiting:<br>
+ <br>
+ <a href="collink.html">collink</a> <a href="collink.html#v">-v</a>
+ <a href="collink.html#q">-qm</a> <a href="collink.html#g">-g</a> <a
+ href="collink.html#si">-ip</a> <a href="collink.html#c">-cmt</a>
+ <a href="collink.html#d">-dpp</a> <a href="collink.html#p1">MonitorSouceProfile.icm</a>
+ <a href="collink.html#p2">DestinationProfile.icm</a> <a
+ href="collink.html#p3">Source2Destination.icm</a><br>
+ <br>
+ [ If your viewing environment for the display and print doesn't
+ match the ones implied by the <a href="colprof.html#c">-cmt</a> and
+ <a href="colprof.html#d">-dpp</a> options, leave them out, and
+ evaluate what, if any appearance transformation is appropriate for
+ your environment at a later stage. ]<br>
+ <br>
+ In <a href="collink.html#G">inverse output table gamut mapping mode</a>,
+ the pre-computed intent mappings inside the profiles are not used,
+ but instead the gamut mapping between source and destination is
+ tailored to the specific gamuts of the two profiles, and the intent
+ parameter supplied to <span style="font-weight: bold;">collink</span>.
+ In addition, the B2A table is <span style="font-weight: bold;">not</span>
+ used in the destination profile, but the A2B table is instead
+ inverted, leading to improved transform accuracy, and in CMYK
+ devices, allowing the ink limiting and black generation parameters
+ to be set:<br>
+ <br>
+ For a CLUT table based RGB printer destination profile, the
+ following would be appropriate:<br>
+ <br>
+ <a href="collink.html">collink</a> <a href="collink.html#v">-v</a>
+ <a href="collink.html#q">-qm</a> <a href="collink.html#G">-G</a> <a
+ href="collink.html#si">-ip</a> <a href="collink.html#c">-cmt</a>
+ <a href="collink.html#d">-dpp</a> <a href="collink.html#p1">MonitorSouceProfile.icm</a>
+ <a href="collink.html#p2">RGBDestinationProfile.icm</a> <a
+ href="collink.html#p3">Source2Destination.icm</a><br>
+ <br>
+ For a CMYK profile, the total ink limit needs to be specified (a
+ typical value being 10% less than the value used in creating the
+ device test chart), and the type of black generation also needs to
+ be specified:<br>
+ <br>
+ <a href="collink.html">collink</a> <a href="collink.html#v">-v</a>
+ <a href="collink.html#q">-qm</a> <a href="collink.html#G">-G</a> <a
+ href="collink.html#si">-ip</a> <a href="collink.html#c">-cmt</a>
+ <a href="collink.html#d">-dpp</a> <a href="collink.html#l">-l250</a>
+ <a href="collink.html#k">-kr</a> <a href="collink.html#p1">MonitorSouceProfile.icm</a>
+ <a href="collink.html#p2">CMYKDestinationProfile.icm</a> <a
+ href="collink.html#p3">Source2Destination.icm</a><br>
+ <br>
+ Note that you should set the source (<a href="collink.html#c">-c</a>)
+ and destination (<a href="collink.html#d">-d</a>) viewing conditions
+ for the type of device the profile represents, and the conditions
+ under which it will be viewed.<br>
+ <br>
+ <h3><a name="LP3"></a>Image dependent gamut mapping using device
+ links<br>
+ </h3>
+ When images are stored in large gamut colorspaces (such as. L*a*b*
+ or ProPhoto, etc.), then using the colorspace gamut as the source
+ gamut for gamut mapping is generally a bad idea, as it leads to
+ overly compressed and dull images. The correct approach is to use a
+ source gamut that represents the gamut of the images themselves.
+ This can be created using tiffgamut, and an example workflow is as
+ follows:<br>
+ <br>
+ <a href="tiffgamut.html">tiffgamut</a> -f80 -pj -cmt ProPhoto.icm
+ image.tif<br>
+ <br>
+ <a href="collink.html">collink</a> <a href="collink.html#v">-v</a>
+ <a href="collink.html#q">-qh</a> <a href="collink.html#G">-G</a> <a
+ href="collink.html#Gp">image.gam</a> <a href="collink.html#si">-ip</a>
+ <a href="collink.html#c">-cmt</a> <a href="collink.html#d">-dpp</a>
+ <a href="collink.html#p1">ProPhoto.icm</a> <a
+ href="file:///D:/src/argyll/doc/collink.html#p2">RGBDestinationProfile.icm</a>
+ <a href="file:///D:/src/argyll/doc/collink.html#p3">Source2Destination.icm</a><br>
+ <br>
+ <a href="file:///D:/src/argyll/doc/cctiff.html">cctiff</a> <a
+ href="file:///D:/src/argyll/doc/cctiff.html#p1">Source2Destination.icm</a>
+ <a href="file:///D:/src/argyll/doc/cctiff.html#p3">image.tif</a> <a
+ href="file:///D:/src/argyll/doc/cctiff.html#p4">printfile.tif</a><br>
+ <br>
+ The printfile.tif is then send to the printer without color
+ management, (i.e. in the same way the printer characterization test
+ chart was printed), since it is in the printers native colorspace.<br>
+ <br>
+ You can adjust how conservatively the image gamut is preserved using
+ the tiffgamut -f parameter. Omitting it or using a larger value (up
+ to 100) preserves the color gradations of even the lesser used
+ colors, at the cost of compressing the gamut more.<br>
+ Using a smaller value will preserve the saturation of the most
+ popular colors, at the cost of not preserving the color gradations
+ of less popular colors.<br>
+ <br>
+ You can create a gamut that covers a set of source images by
+ providing more than one image file name to tiffgamut. This may be
+ more efficient for a group of related images, and ensures that
+ colors are transformed in exactly the same way for all of the
+ images.<br>
+ <br>
+ The arguments to collink should be appropriate for the output device
+ type - see the collink examples in the above section.<br>
+ <h3><a name="LP2"></a>Soft Proofing Link</h3>
+ Often it is desirable to get an idea what a particular devices
+ output will look like using a different device. Typically this might
+ be trying to evaluate print output using a display. Often it is
+ sufficient to use an absolute or relative colorimetric transform
+ from the print device space to the display space, but while these
+ provide a colorimetric preview of the result, they do not take into
+ account the subjective appearance differences due to the different
+ device conditions. It can therefore be useful to create a soft proof
+ appearance transform using collink:<br>
+ <br>
+ <a href="collink.html">collink</a> <a href="collink.html#v">-v</a>
+ <a href="collink.html#q">-qm</a> <a href="collink.html#G">-G</a> <a
+ href="collink.html#si">-ila</a> <a href="collink.html#c">-cpp</a>
+ <a href="collink.html#d">-dmt</a> <a href="collink.html#l">-t250</a> <a
+ href="collink.html#k"></a><a href="collink.html#p1">CMYKDestinationProfile.icm</a>
+ <a href="collink.html#p2">MonitorProfile.icm</a> <a
+ href="collink.html#p3">SoftProof.icm</a><br>
+ <br>
+ We use the Luminance matched appearance intent, to preserve the
+ subjective apperance of the target device, which takes into account
+ the viewing conditions and assumes adaptation to the differences in
+ the luminence range, but otherwise not attempting to compress or
+ change the gamut.<br>
+ <br>
+ If your viewing environment for the display and print doesn't match
+ the ones implied by the <a href="collink.html#c">-cpp</a> and <a
+ href="collink.html#d">-dmt</a> options, then either leave them out
+ or substitute values that do match your environment.<br>
+
+ <hr size="2" width="100%"><br>
+ <h3><a name="TR1"></a>Transforming colorspaces of raster files</h3>
+ Although a device profile or device link profile may be useful with
+ other programs and systems, Argyll provides the tool <a
+ href="cctiff.html">cctiff</a> for directly applying a device to
+ device transform to a <a href="File_Formats.html#TIFF">TIFF</a> or
+ <a href="File_Formats.html#JPEG">JPEG</a> raster file. The cctiff
+ tool is capable of linking an arbitrary sequence of device profiles,
+ device links, abstract profiles and calibration curves. Each device
+ profile can be preceded by the <span style="font-weight: bold;">-i</span>
+ option to indicate the intent that should be used. Both 8 and 16 bit
+ per component files can be handled, and up to 8 color channels. The
+ color transform is optimized to perform the overall transformation
+ rapidly.<br>
+ <br>
+ If a device link is to be used, the following is a typical example:<br>
+ <br>
+ <a href="cctiff.html">cctiff</a> <a href="cctiff.html#p1">Source2Destination.icm</a>
+ <a href="cctiff.html#p3">infile.tif</a> <a href="cctiff.html#p4">outfile.tif</a><br>
+ or<br>
+ <a href="cctiff.html">cctiff</a> <a href="cctiff.html#p1">Source2Destination.icm</a>
+ <a href="cctiff.html#p3">infile.jpg</a> <a href="cctiff.html#p4">outfile.jpg</a><br>
+ <br>
+ <i><br>
+ </i>If a source and destination profile are to be used, the
+ following would be a typical example:<br>
+ <br>
+ <a href="cctiff.html"> cctiff</a> <a href="cctiff.html#i">-ip</a>
+ <a href="cctiff.html#p1i">SourceProfile.icm</a> <a
+ href="cctiff.html#i">-ip</a> <a href="cctiff.html#p1o">DestinationProfile.icm</a>
+ <a href="cctiff.html#p3">infile.tif</a> <a href="cctiff.html#p4">outfile.tif</a><br>
+ or<br>
+ <a href="cctiff.html"> cctiff</a> <a href="cctiff.html#i">-ip</a>
+ <a href="cctiff.html#p1i">SourceProfile.icm</a> <a
+ href="cctiff.html#i">-ip</a> <a href="cctiff.html#p1o">DestinationProfile.icm</a>
+ <a href="cctiff.html#p3">infile.jpg</a> <a href="cctiff.html#p4">outfile.jpg</a><br>
+ <br>
+ <br>
+ <hr size="2" width="100%"><br>
+ <h3><a name="TV1"></a>Creating Video Calibration 3DLuts</h3>
+ Video calibration typically involves trying to make your actual
+ display device emulate an ideal video display, one which matches
+ what your Video media was intended to be displayed on. An ICC device
+ link embodies the machinery to do exactly this, to take device
+ values in the target source colorspace and transform them into an
+ actual output device colorspace. In the Video and Film industries a
+ very similar, but less sophisticated means of doing this is to use
+ 3DLuts, which come in a multitude of different format. ICC device
+ links have the advantage of being a superset of 3dLuts, encapsulated
+ in a standard file format.<br>
+ <br>
+ To facilitate Video calibration of certain Video systems, ArgyllCMS
+ supports some 3DLut output options as part of <a
+ href="collink.html">collink</a>.<br>
+ <br>
+ What follows here is an outline of how to create Video calibration
+ 3DLuts using ArgyllCMS. First comes a general discussion of various
+ aspects of video device links/3dLuts, and followed with some
+ specific advice regarding the systems that ArgyllCMS supports. Last
+ is some recommended scenarios for verifying the quality of Video
+ calibration achieved.<br>
+ <h5>1) How to display test patches.<br>
+ </h5>
+ Argyll's normal test patch display will be used by default, as long
+ as any video encoding range considerations are dealt with (see
+ Signal encoding below).<br>
+ <br>
+ An alternative when working with MadVR V 0.86.9 or latter, is to use
+ the madTPG to display the patches in which case the MadVR video
+ encoding range setting will operate. This can give some quality
+ benefits due to MadVR's use of dithering. To display patches using
MadVR rather than Argyll, start madTPG and then use the option "<b>-d - - - - madvr</b>" in dispcal, dispread and dispwin. Leave the MadTPG - "VideoLUT" and "3dluts" buttons in their default (enabled) - state, as the various tools will automatically take care of - disabling the 3dLut and/or calibration curves as needed.<br> - <br> - Another option is to use a <a - href="http://en.wikipedia.org/wiki/Chromecast">ChromeCast</a> - using the option "<b>-dcc</b>" in dispcal, dispread and dispwin. - Note that the ChromeCast as a test patch source is probably the<b> - least accurate</b> of your choices, since it up-samples the test - patch and transforms from RGB to YCC and back, but should be - accurate within ± 1 bit. You may have to modify any firewall to - permit port 8081 to be accessed on your machine if it falls back to - the Default receiver (see <a href="Installing.html">installation - instructions</a> for your platform). - <h5>2) White point calibration & neutral axis calibration.</h5> - A Device Link is capable of embodying all aspects of the - calibration, including correcting the white point and neutral axis - behavior of the output device, but making such a Link just from two - ICC profile requires the use of Absolute Colorimetric intent during - linking, and this reduces flexibility. In addition, a typical ICC - device profile may not capture the neutral axis behavior quite as - well as an explicit calibration, since it doesn't sample the - displays neutral axis behaviour in quite as much detail. It is often - desirable therefore, to calibrate the display device so as to have - the specific white point desired so that one of the white point - relative linking intents can be used, and to improve the displays - general neutral axis behavior so that subsequent profiling works to - best advantage. In summary, there are basically 4 options in - handling white point & neutral axis calibration:<br> - <ul> - <li>Don't bother correcting the white point. Most displays are - close to the typical D65 target, and our eyes adapt to the white - automatically unless it is very far from the daylight locus or - we have something else to refer to. If this approach is taken, - then display profiling and linking can ignore calibration, and - one of the non Absolute Colorimetric intents (such as Relative - Colorimetric) is chosen during profile linking. It is wise to - make sure that the video card VideoLUTs are set to some known - state (ie. linear using "dispwin -c" , or set by a an installed - ICC display profile) though.<br> - </li> - <li>Calibrate the white point and linearise the neutral axis using - the display controls. Many TV's have internal calibration - controls that allow setting the white point, and possibly the - neutral axis response. Either a dedicated Video calibration +
+ madvr</b>" in dispcal, dispread and dispwin. Leave the MadTPG
+ "VideoLUT" and "3dluts" buttons in their default (enabled)
+ state, as the various tools will automatically take care of
+ disabling the 3dLut and/or calibration curves as needed.<br>
+ <br>
+ Another option is to use a <a
+ href="http://en.wikipedia.org/wiki/Chromecast">ChromeCast</a>
+ using the option "<b>-dcc</b>" in dispcal, dispread and dispwin.
+ Note that the ChromeCast as a test patch source is probably the<b>
+ least accurate</b> of your choices, since it up-samples the test
+ patch and transforms from RGB to YCC and back, but should be
+ accurate within ± 1 bit. You may have to modify any firewall to
+ permit port 8081 to be accessed on your machine if it falls back to
+ the Default receiver (see <a href="Installing.html">installation
+ instructions</a> for your platform).
+ <h5>2) White point calibration & neutral axis calibration.</h5>
+ A Device Link is capable of embodying all aspects of the
+ calibration, including correcting the white point and neutral axis
+ behavior of the output device, but making such a Link just from two
+ ICC profile requires the use of Absolute Colorimetric intent during
+ linking, and this reduces flexibility. In addition, a typical ICC
+ device profile may not capture the neutral axis behavior quite as
+ well as an explicit calibration, since it doesn't sample the
+ displays neutral axis behaviour in quite as much detail. It is often
+ desirable therefore, to calibrate the display device so as to have
+ the specific white point desired so that one of the white point
+ relative linking intents can be used, and to improve the displays
+ general neutral axis behavior so that subsequent profiling works to
+ best advantage. In summary, there are basically 4 options in
+ handling white point & neutral axis calibration:<br>
+ <ul>
+ <li>Don't bother correcting the white point. Most displays are
+ close to the typical D65 target, and our eyes adapt to the white
+ automatically unless it is very far from the daylight locus or
+ we have something else to refer to. If this approach is taken,
+ then display profiling and linking can ignore calibration, and
+ one of the non Absolute Colorimetric intents (such as Relative
+ Colorimetric) is chosen during profile linking. It is wise to
+ make sure that the video card VideoLUTs are set to some known
+ state (ie. linear using "dispwin -c" , or set by a an installed
+ ICC display profile) though.<br>
+ </li>
+ <li>Calibrate the white point and linearise the neutral axis using
+ the display controls. Many TV's have internal calibration
+ controls that allow setting the white point, and possibly the
+ neutral axis response. Either a dedicated Video calibration
package could be used, or ArgyllCMS <a href="dispcal.html">dispcal</a>'s @@ -3274,30 +3215,28 @@ a - - - - interactive adjustment mode can be used to set the white point. - Note that while adjusting the neutral axis for neutrality may - help, the Device Link will override the transfer curve - characteristic of the calibrated display, so aiming for a - transfer curve approximately the same as the target and - reasonably perceptually linear is all that is required. If this - approach is taken, then display profiling and linking can ignore - calibration, and one of the non Absolute Colorimetric intents is - chosen during profile linking. It is wise to make sure that the - video card VideoLUTs are set to some known state though.</li> - <li>[<b>Recommended</b>] Calibrate the white point and neutral - axis using ArgyllCMS <a href="dispcal.html">dispcal</a>. Since - the Device Link will override the calibrated transfer curve - characteristic of the display, there there may be no point in - doing much more than a medium calibration, and choosing a - standard that has a straight segment from black, such as L*a*b*, - sRGB, Rec709 or SMPTE240 curve. The exact shape of the - calibration curve is not critically important, as the profiling - and 3dLut will set the final response. If this approach is - taken, then the resulting calibration file should be provided to - dispread as the <a href="dispcal.html#k">-k parameter</a> or <a +
+ interactive adjustment mode can be used to set the white point.
+ Note that while adjusting the neutral axis for neutrality may
+ help, the Device Link will override the transfer curve
+ characteristic of the calibrated display, so aiming for a
+ transfer curve approximately the same as the target and
+ reasonably perceptually linear is all that is required. If this
+ approach is taken, then display profiling and linking can ignore
+ calibration, and one of the non Absolute Colorimetric intents is
+ chosen during profile linking. It is wise to make sure that the
+ video card VideoLUTs are set to some known state though.</li>
+ <li>[<b>Recommended</b>] Calibrate the white point and neutral
+ axis using ArgyllCMS <a href="dispcal.html">dispcal</a>. Since
+ the Device Link will override the calibrated transfer curve
+ characteristic of the display, there there may be no point in
+ doing much more than a medium calibration, and choosing a
+ standard that has a straight segment from black, such as L*a*b*,
+ sRGB, Rec709 or SMPTE240 curve. The exact shape of the
+ calibration curve is not critically important, as the profiling
+ and 3dLut will set the final response. If this approach is
+ taken, then the resulting calibration file should be provided to
+ dispread as the <a href="dispcal.html#k">-k parameter</a> or <a
href="dispcal.html#K">-K parameter</a>. See also below <b>Choice @@ -3310,478 +3249,476 @@ a - - - - of where to apply display per channel calibration curves.</b></li> - <li>Choose one of the Absolute Colorimetric intents in collink - (ie. -i aw). This greatly reduces flexibility, and may not be - quite as accurate as an explicit calibration.</li> - </ul> - If an explicit calibration is used, then it is a good idea to add - some test points down the neutral axis when profiling (targen <a - href="targen.html#g">-g parameter</a>). <br> - <br> - <b>3) Choice of where to apply display per channel calibration - curves</b><br> - <br> - If calibration curves are going to be used, then it needs to be - decided where they will be applied in the video processing chain. - There are two options:<br> - <br> - <b>a)</b> Install the calibration curves in the playback system. On - a PC the display, this can be done by loading the calibration curves - into the Video Card temporarily using "dispwin calibration.cal", or - installing the ICC profile into the system persistently using - something like "<a href="dispwin.html#I">dispwin -I profile.icm</a>",<br> - or when using MadVR 0.86.9 or latter by creating a 3dLut with - appended calibration curves using <a href="collink#H">-H - display.cal</a>.<br> - <br> - <b>b)</b> The calibration can be incorporated into the Device - Link/3dLUT by providing it to collink as the <a - href="collink.html#a">-a display.cal</a>. This is the only option - if the video display path does not have some separate facility to - handle calibration curves. Note that if the playback system has - graphic card VideoLUTs then they will have to be set to a defined - consistent state such as linear. When using MadVR 0.86.9 or latter - this will be done automatically since the -a option will append a - linear set of calibration curves to the 3dLut.<br> - <br> - The choice is dictated by a number of considerations:<br> - <ul> - <li>Does the video playback path have a facility for installing - the calibration curves ? If playing back system is a PC, then - typically the Graphics Card supports 1D VideoLUTs, thereby - making a) a possible choice.<br> - </li> - <li>Does the video playback <u>always</u> play back through the - Video Card VideoLUTs ? Some systems do not apply VIdeoLUTs to - things like overlay plane rendering. If not, then you need to - choose b), but also make sure that if it does use the Video Card - VideoLUTs in some situations, that they are set to linear (ie. - dispcal -c). One way of determining when the VideoLUTs get used - or not is to load a distinct calibration such as "strange.cal" - provided in the <b>ref</b> folder, and check visually if it is - affecting the video or not, ie. "dispcal strange.cal". Note that - using MadVR 0.86.9 or latter in combination with a 3dLut with - appended calibration curves will apply the calibration even with - overlay plane rendering.<br> - </li> - <li>Do you want/need other applications to share the calibration - curves or profile or not ? If you do, then it is desirable to - choose a).</li> - <li>Quality considerations. VideoLUTs may or may not be of greater - depth than the standard 8 bit per color component frame buffer. - If they are, and the video path passes that extra depth through - to the display, and the display is capable of using that extra - depth, then a) may be a desirable choice from a quality point of - view. You can get some idea whether this is the case by running - "dispcal -R". If the VideoLUT depth is not better than 8 bits, - then it may be more desirable to choose b), since renders like - MadVR can use dithering to give better than 8 bits precision in - the video playback.<br> - </li> - </ul> - <h5>4) Output device calibration and profiling.</h5> - Output device profiling should basically follow the guide above in <a - href="#PM1b">Adjusting and Calibrating a displays</a> and <a - href="#PM1">Profiling Displays</a>. The assumption is that either - you are calibrating/profiling your computer display for video, or - your TV is connected to the computer you are creating - calibrations/profiles on, and that the connection between the PC and - TV display is such that full range RGB signals are being used, or - that the Video card has automatically or manually been configured to - scale full range RGB values to Video levels for the TV. If the - latter is not possible, then use the -E options on dispcal and - dispread. (See <b>Signal encoding</b> bellow for more details on - this). It may also improve the accuracy of the display profile if - you use the <a href="dispread.html#Z">dispread -Z</a> option to - quantize the test values to the precision of the display - system. Don't use the -E options on dispcal and dispread, nor - the -Z option on dispread if you are using MadVR to display test - patches using the "-d madvr" option.<br> - <br> - Once the profile has been created, it is possible to then use the - resulting Device Link/3DLut with signal encoding other than full - range or Video level RGB. <br> - <h5>5) Target colorspace<br> - </h5> - In practical terms, there are five common Video and Digital Cinema - encoding colorspaces. <br> - <br> - For Standard Definition:<br> - <br> - EBU 3213 or "PAL 576i" primaries.<br> - <br> - SMPTE RP 145 or "NTSC 480i" primaries.<br> - <br> - For High Definition:<br> - <br> - Rec 709 primaries.<br> - <br> - For Ultra High Defintion<br> - <br> - Rec 2020 primaries.<br> - <br> - For Digital Cinema<br> - <br> - SMPTE-431-2 or "DCI-P3"<br> - <br> - PAL and NTSC have historically had poorly specified transfer curve - encodings, and the Rec 709 HDTV encoding curve is the modern <a - href="http://www.poynton.com/notes/DVAI/DVAI_TOC_full.html#23">recommendation</a>, - but the overall interpretation of Video sources may in fact be - partly determined by the expected standard Video display device - characteristics (see <b>Viewing conditions adjustment and gamut - mapping</b> below for more details).<br> - <br> - To enable targeting these colorspaces, ArgyllCMS provides 5 ICC - profiles in the ref directory to use as source - colorspaces: <br> - <br> - EBU3213_PAL.icm<br> - <br> - SMPTE_RP145_NTSC.icm<br> - <br> - Rec709.icm<br> - <br> - Rec2020.icm<br> - <br> - SMPTE431_P3.icm<br> - <h5>6) Signal encoding</h5> - Typical PC display output uses full range RGB signals (0 .. 255 in 8 - bit parlance), while typical Video encoding allows some head & - footroom for overshoot and sync of digitized analog signals, and - typically uses a 16..235 range in 8 bits. In many cases Video is - encoded as luma and color difference signals YCbCr (loosely known as - YUV as well), and this also uses a restricted range 16..235 for Y, - and 16..240 for Cb and Cr in 8 bit encoding. The extended gamut - xvYCC encoding uses 16..235 for Y, and 1..254 for Cb and Cr.<br> - <br> - The signal encoding comes into play in two situations: 1) - Calibrating and profiling the display, and 2) Using the resulting - Device Link/3DLut.<br> - The encoding may need to be different in these two situations, - either because different video source devices are being used for - calibration/profiling and for video playback, or because the video - playback system uses the Device Link/3DLut at a point in its - processing pipeline that requires a specific encoding.<br> - <br> - For calibration & profiling, the display will be driven by a - computer system so that dispcal and dispread can be used. By default - these programs expect to output full range RGB signals, and it is - assumed that either the display accepts full range signals, or that - the graphics card or connection path has been setup to convert the - full range values into Video range signals automatically or - manually. If this is not the case, then both dispcal and dispread - have a -E option that will modify them to output Video range RGB - values.<br> - <br> - If MadVR is the target of the calibration and profiling, then there - is an option to use it to display the calibration and profiling test - patches (<b>-d madvr</b>). In this case, MadVR should be configured - appropriately for full range or Video range encoding, and the -E - flag should <u>not</u> be used with dispcal or dispread, since - MadVR will be taking care of such conversions.<br> - <br> - If a calibration file was created using dispcal -E, then using it in - dispread will automatically trigger Video level RGB signals during - profiling. Any time such a Video level calibration is loaded into - the Graphics card VideoLUTs using dispwin, or the calibration curve - is converted to a 'vcgt' tag in a profile, the curve will also - convert full range RGB to Video range RGB. This should be kept in - mind so that if video playback is being performed with the - calibration curves installed in the Graphics card VideoLUTs, that - full range is converted only once to Video range (ie. In this - situation MadVR output should be set to full range if being played - back through the calibration curves in hardware, but only if dispcal - -E has been used). On the other hand, if the calibration curves are - incorporated into the DeviceLink/3dLUT, then the conversion to Video - levels has to be done somewhere else in the pipeline, such as using - MadVR video level output, or by the graphics card, etc.<br> - <br> - When creating the Device Link/3dLut, it is often necessary to - specify one of the video encodings so that it fits in to the - processing pipeline correctly. For instance the eeColor needs to - have input and output encoding that suits the HDMI signals passing - through it, typically Video Range RGB. MadVR needs Video Level RGB - to match the values being passed through the 3dLut at that point.<br> - <br> - There are several version of YCbCr encoding supported as well, even - though neither the eeColor nor the current version of MadVR need or - can use them at present.<br> - <h5>7) Black point mapping</h5> - <p>Video encoding assumes that the black displayed on a device is a - perfect black (zero light). No real device has a perfect black, - and if a colorimetric intent is used then certain image values - near black will get clipped to the display black point, loosing - shadow detail. To avoid this, some sort of black point mapping is - usually desirable. There are two mechanisms available in collink: - a) Custom EOTF with input and/or output black point mapping, or b) - using one of the smart gamut mapping intents that does black point - mapping (e.g. la, p, pa, ms or s).<br> - </p> - <h5>8) Viewing conditions adjustment and gamut mapping</h5> - <p> </p> - <p>In historical TV systems, there is a viewing conditions - adjustment being made between the bright studio conditions that TV - is filmed in, and the typical dim viewing environment that people - view it in. This is created by the difference between the encoding - response curve gamma of about 2.0, and a typical CRT response - curve gamma of 2.4. <br> - </p> - <p>In theory Rec709 defines the video encoding, but it seems in - practice that much video material is adjusted to look as intended - when displayed on a reference monitor having a display gamma of - somewhere between 2.2 and 2.4, viewed in a dim viewing - environment. The modern standard covering the display EOTF - (Electro-Optical Transfer Curve) is <a - href="http://www.itu.int/rec/R-REC-BT.1886-0-201103-I">BT.1886</a>, - which defines a pure power 2.4 curve with an input offset and - scale applied to account for the black point offset while - retaining dark shadow tonality. So another means of making the - viewing adjustment is to use the BT.1886-like EOTF for Rec709 - encoded material. Collink supports this using the <a - href="collink.html#I">-I b</a>, and allows some control over the - degree of viewing conditions adjustment by overriding the BT.1886 - gamma using the <a href="collink.html#Ib">-I b:g.g</a> - parameter. This is the <b>recommended</b> approach to start with, - since it gives good results with a single parameter.<br> - </p> - <p>The addition of a second optional parameter <a - href="collink.html#Ib">-I b:p.p:g.g</a> - allows control over the degree of black point offset accounted for - as an output offset, as opposed to input offset Once the effective - gamma value has been chosen to suite the viewing conditions and - set the overall contrast for mid greys, increasing the proportion - of black offset accounted for in the output of the curve is a way - of reducing the deep shadow detail, if it is being overly - emphasized. </p> - <p> An alternate approach to making this adjustment is to take - advantage of the viewing conditions adjustment using the CIECAM02 - model available in collink. Some control over the degree of - viewing conditions adjustment is possible by varying the viewing - condition parameters. </p> - <p>A third alternative is to combine the two approaches. The source - is defined as Rec709 primaries with a BT.1886-like EOTF display in - dim viewing conditions, and then CIECAM02 is used to adjust for - the actual display viewing conditions. Once again, control over - the degree of viewing conditions adjustment is possible by varying - the viewing condition parameters<br> - </p> - <p><br> - </p> - <p><b>9) Correcting for any black point inaccuracy in the display - profile</b><br> - </p> - <p>Some video display devices have particularly good black points, - and any slight raising of the black due to innacuracies in the - display profile near black can be objectionable. As well as using - the <a href="targen.html#V">targen -V flag</a> to improve - accuracy near black during profiling, if the display is known to - be well behaved (ie. that it's darkest black is actually at RGB - value 0,0,0), then the <a href="collink.html#b">collink -b</a> - flag can be used, to force the source RGB 0,0,0 to map to the - display 0,0,0.<br> - </p> - <h5>Putting it all together:</h5> - In this example we choose to create a display calibration first - using dispcal, and create a simple matrix profile as well:<br> - <br> - <tt>dispcal -v -o -qm -k0 -w 0.3127,0.3290 -gs -o TVmtx.icm - TV</tt><br> - <br> - We are targeting a D65 white point (<tt>-w 0.3127,0.3290)</tt> and - an sRGB response curve.<br> - <br> - If you are using the madTPG you would use:<br> - <br> - <tt>dispcal -v -d madvr -o -qm -k0 -w 0.3127,0.3290 -gs -o - TVmtx.icm TV</tt><br> - <br> - Then we need to create a display patch test set. We can use the - simple matrix to pre-condition the test patches, as this helps - distribute them where they will be of most benefit. If have - previously profiled your display, you should use that previous - profile, or if you decided not to do a dispcal, then the Rec709.icm - should be used as a substitute. Some per channel and a moderate - number of full spread patches is used here - more will increase - profiling accuracy, a smaller number will speed it up. Since the - video or film material is typically viewed in a darkened viewing - environment, and often uses a range of maximum brightnesses in - different scenes, the device behavior in the dark regions of its - response are often of great importance, and using the <a - href="targen.html#V">targen -V</a> parameter can help improve the - accuracy in this region at the expense of slightly lower accuracy in - lighter regions.<br> - <br> - <tt>targen -v -d3 -s30 -g100 -f1000 -cTVmtx.icm -V1.8 TV</tt><br> - <br> - The display can then be measured:<br> - <br> - <tt>dispread -v -k -Z8 TV.cal TV</tt><br> - <br> - or using madTPG:<br> - <br> - dispread -v -d madvr -K TV.cal TV<br> - <br> - and then a cLUT type ICC profile created. Since we will be using - collink smart linking, we minimize the B2A table size. We use the - default colprof -V parameter carried through from targen:<br> - <br> - <tt>colprof -v -qh -bl TV</tt><br> - <br> - Make sure you check the delta E report at the end of the profile - creation, to see if the sample data and profile is behaving - reasonably. Depending on the type of device, and the consistency of - the readings, average errors of 5 or less, and maximum errors of 15 - or less would normally be expected. If errors are grossly higher - than this, then this is an indication that something is seriously - wrong with the device measurement, or profile creation.<br> - <br> - If you would like to use the display ICC profile for general color - managed applications, then you would compute a more complete - profile:<br> - <br> - <tt>colprof -v -qh TV</tt><br> - <br> - The recommended approach then is to create a Device Link that uses a - BT.1886 black point and viewing conditions adjustment, say one of - the following:<br> - <br> - <tt> collink -v -Ib:2.4 -b -G -ir Rec709.icm TV.icm - HD.icm # dark conditions</tt><tt><br> - </tt><tt> collink -v -Ib -b -G -ir - Rec709.icm TV.icm HD.icm # dim conditions - good - default</tt><tt><br> - </tt><tt> collink -v -Ib:2.1 -b -G -ir Rec709.icm TV.icm - HD.icm # mid to dim conditions</tt><tt><br> - </tt><tt> collink -v -Ib:2.0 -b -G -ir Rec709.icm TV.icm - HD.icm # mid to light conditions</tt><br> - <br> - or you could do it using pure CIECAM02 adjustment and a black point - mapping:<br> - <br> - <tt> collink -v -ctv -dmd -da:1 -G -ila Rec709.icm TV.icm - HD.icm # very dark conditions</tt><tt><br> - </tt><tt> collink -v -ctv -dmd -da:3 -G -ila Rec709.icm - TV.icm HD.icm # dim conditions</tt><tt><br> - </tt><tt> collink -v -ctv -dmd -da:7 -G -ila Rec709.icm - TV.icm HD.icm # mid to dim conditions - good default</tt><tt><br> - </tt><tt> collink -v -ctv -dmd -da:15 -G -ila Rec709.icm - TV.icm HD.icm # mid conditions</tt><br> - <br> - or using both to model a reference video display system that is - adapted to your viewing conditions:<br> - <tt><br> - </tt><tt> collink -v -Ib -c md -dmd -da:5 -G -ila - Rec709.icm TV.icm HD.icm # very dark conditions</tt><tt><br> - </tt><tt> collink -v -Ib -c md -dmd -da:10 -G -ila Rec709.icm - TV.icm HD.icm # dim conditions</tt><tt><br> - </tt><tt> collink -v -Ib -c md -dmd -da:18 -G -ila Rec709.icm - TV.icm HD.icm # mid to dark conditions</tt><tt><br> - </tt><tt> collink -v -Ib -c md -dmd -da:30 -G -ila Rec709.icm - TV.icm HD.icm # mid to dark conditions</tt><br> - <br> - None of the above examples incorporate the calibration curves, so it - is assumed that the calibration curves would be installed so that - the Video Card applies calibration, ie:<br> - <br> - <tt>dispwin TV.cal</tt><br> - <br> - or the simple matrix profile installed:<br> - <br> - <tt>dispwin -I TVmtx.icm</tt><br> - <br> - or a the more complete display profile could be installed:<br> - <br> - dispwin -I TV.icm<br> - <br> - See also <a href="dispprofloc.html">here</a> for information on how - to make sure the calibration is loaded on each system start. If not, - then you will want to incorporate the calibration in the Device - Link/3dlut by using collink "-a TV.cal".<br> - <br> - If the video path needs Video Level RGB encoding but does not - provide a means to do this, then you will want to include the <b>-E</b> - flag in the dispcal and dispread command lines above.<br> - <br> - Below are specific recommendation for the eeColor and MadVR that - include the flags to create the .3dlut and encode the input and - output values appropriately, but only illustrate using the - recommended BT.1886 black point and viewing conditions adjustments, - rather than illustrating CIECAM02 etc. use.<br> - <br> - For faster exploration of different collink option, you could omit - the "colprof -bl" option, and use collink "-g" instead of "-G", - since this<br> - will greatly speed up collink. Once you are happy with the link - details, you can then generate a higher quality link/3dLut using - "collink -G ..".<br> - <br> - You can also increase the precision of the device profile by - increasing the number of test patches measured (ie. up to a few - thousand, depending on how long you are prepared to wait for the - measurement to complete, and how stable your display and instrument - are).<br> - <br> - Alternatives to relative colorimetric rendering ("-i r") or - luminance matched appearance ("-i la") used in the examples above - and below, are, perceptual ("-i p") which will ensure that the - source gamut is compressed rather than clipped by the display, or - even a saturation rendering ("-i ms"), which will expand the gamut - of the source to the full range of the output.<br> - <br> - <br> - <b>eeColor</b><br> - <br> - For PC use, where the encoding is full range RGB:<br> - <br> - <tt>collink -v -3e -Ib -b -G -ir -a TV.cal Rec709.icm TV.icm - HD.icm </tt><br> - <br> - For correct operation both the 3DLut HD.txt and the per channel - input curves HD-first1dred.txt, HD-first1dgreen.txt and - HD-first1dblue.txt. the latter by copying them over the default - input curve files uploaded by the TruVue application.<br> - <br> - See <a - href="http://www.avsforum.com/t/1464890/eecolor-processor-argyllcms"><http://www.avsforum.com/t/1464890/eecolor-processor-argyllcms></a> - for some more details.<br> - <br> - Where the eeColor is connected from a Video source using HDMI, it - will probably be processing TV RGB levels, or YCbCr encoded signals - that it converts to/from RGB internally, so<br> - <br> - <tt>collink -v -3e -et -Et -Ib -b -G -ir -a TV.cal - Rec709.icm TV.icm HD.icm </tt><br> - <br> - in this case just the HD.txt file needs installing on the eeColor, - but make sure that the original linear "first1*.txt files are - re-installed, or install the ones generated by collink, which will - be linear for -e t mode.<br> - <br> - <b>MadVR</b><br> - <br> - MadVR 0.86.9 or latter has a number of features to support accurate - profiling and calibration, and is the recommended version to - use. It converts from the media colorspace to the 3dLut input - space automatically with the type of source being played, but has - configuration for to 5 3dLuts, each one optimized for a particular - source color space. The advantage of building and installing several - 3dLuts is that unnecessary gamut clipping can be avoided.<br> - <br> - If you are just building one 3dLut then Rec709 source is a good one - to pick.<br> - <br> - If you want to share the VideoLUT calibration curves between your - normal desktop and MadVR, then it is recommended that you install - the display ICC profile and use the -H option:<br> - <br> - <tt> collink -v -3m -et -Et -Ib -b -G -ir -H - TV.cal Rec709.icm TV.icm HD.icm</tt><tt><br> - </tt><tt> </tt><tt><br> +
+ of where to apply display per channel calibration curves.</b></li>
+ <li>Choose one of the Absolute Colorimetric intents in collink
+ (ie. -i aw). This greatly reduces flexibility, and may not be
+ quite as accurate as an explicit calibration.</li>
+ </ul>
+ If an explicit calibration is used, then it is a good idea to add
+ some test points down the neutral axis when profiling (targen <a
+ href="targen.html#g">-g parameter</a>). <br>
+ <br>
+ <b>3) Choice of where to apply display per channel calibration
+ curves</b><br>
+ <br>
+ If calibration curves are going to be used, then it needs to be
+ decided where they will be applied in the video processing chain.
+ There are two options:<br>
+ <br>
+ <b>a)</b> Install the calibration curves in the playback system. On
+ a PC the display, this can be done by loading the calibration curves
+ into the Video Card temporarily using "dispwin calibration.cal", or
+ installing the ICC profile into the system persistently using
+ something like "<a href="dispwin.html#I">dispwin -I profile.icm</a>",<br>
+ or when using MadVR 0.86.9 or latter by creating a 3dLut with
+ appended calibration curves using <a href="collink#H">-H
+ display.cal</a>.<br>
+ <br>
+ <b>b)</b> The calibration can be incorporated into the Device
+ Link/3dLUT by providing it to collink as the <a
+ href="collink.html#a">-a display.cal</a>. This is the only option
+ if the video display path does not have some separate facility to
+ handle calibration curves. Note that if the playback system has
+ graphic card VideoLUTs then they will have to be set to a defined
+ consistent state such as linear. When using MadVR 0.86.9 or latter
+ this will be done automatically since the -a option will append a
+ linear set of calibration curves to the 3dLut.<br>
+ <br>
+ The choice is dictated by a number of considerations:<br>
+ <ul>
+ <li>Does the video playback path have a facility for installing
+ the calibration curves ? If playing back system is a PC, then
+ typically the Graphics Card supports 1D VideoLUTs, thereby
+ making a) a possible choice.<br>
+ </li>
+ <li>Does the video playback <u>always</u> play back through the
+ Video Card VideoLUTs ? Some systems do not apply VIdeoLUTs to
+ things like overlay plane rendering. If not, then you need to
+ choose b), but also make sure that if it does use the Video Card
+ VideoLUTs in some situations, that they are set to linear (ie.
+ dispcal -c). One way of determining when the VideoLUTs get used
+ or not is to load a distinct calibration such as "strange.cal"
+ provided in the <b>ref</b> folder, and check visually if it is
+ affecting the video or not, ie. "dispcal strange.cal". Note that
+ using MadVR 0.86.9 or latter in combination with a 3dLut with
+ appended calibration curves will apply the calibration even with
+ overlay plane rendering.<br>
+ </li>
+ <li>Do you want/need other applications to share the calibration
+ curves or profile or not ? If you do, then it is desirable to
+ choose a).</li>
+ <li>Quality considerations. VideoLUTs may or may not be of greater
+ depth than the standard 8 bit per color component frame buffer.
+ If they are, and the video path passes that extra depth through
+ to the display, and the display is capable of using that extra
+ depth, then a) may be a desirable choice from a quality point of
+ view. You can get some idea whether this is the case by running
+ "dispcal -R". If the VideoLUT depth is not better than 8 bits,
+ then it may be more desirable to choose b), since renders like
+ MadVR can use dithering to give better than 8 bits precision in
+ the video playback.<br>
+ </li>
+ </ul>
+ <h5>4) Output device calibration and profiling.</h5>
+ Output device profiling should basically follow the guide above in <a
+ href="#PM1b">Adjusting and Calibrating a displays</a> and <a
+ href="#PM1">Profiling Displays</a>. The assumption is that either
+ you are calibrating/profiling your computer display for video, or
+ your TV is connected to the computer you are creating
+ calibrations/profiles on, and that the connection between the PC and
+ TV display is such that full range RGB signals are being used, or
+ that the Video card has automatically or manually been configured to
+ scale full range RGB values to Video levels for the TV. If the
+ latter is not possible, then use the -E options on dispcal and
+ dispread. (See <b>Signal encoding</b> bellow for more details on
+ this). It may also improve the accuracy of the display profile if
+ you use the <a href="dispread.html#Z">dispread -Z</a> option to
+ quantize the test values to the precision of the display
+ system. Don't use the -E options on dispcal and dispread, nor
+ the -Z option on dispread if you are using MadVR to display test
+ patches using the "-d madvr" option.<br>
+ <br>
+ Once the profile has been created, it is possible to then use the
+ resulting Device Link/3DLut with signal encoding other than full
+ range or Video level RGB. <br>
+ <h5>5) Target colorspace<br>
+ </h5>
+ In practical terms, there are five common Video and Digital Cinema
+ encoding colorspaces. <br>
+ <br>
+ For Standard Definition:<br>
+ <br>
+ EBU 3213 or "PAL 576i" primaries.<br>
+ <br>
+ SMPTE RP 145 or "NTSC 480i" primaries.<br>
+ <br>
+ For High Definition:<br>
+ <br>
+ Rec 709 primaries.<br>
+ <br>
+ For Ultra High Defintion<br>
+ <br>
+ Rec 2020 primaries.<br>
+ <br>
+ For Digital Cinema<br>
+ <br>
+ SMPTE-431-2 or "DCI-P3"<br>
+ <br>
+ PAL and NTSC have historically had poorly specified transfer curve
+ encodings, and the Rec 709 HDTV encoding curve is the modern <a
+ href="http://www.poynton.com/notes/DVAI/DVAI_TOC_full.html#23">recommendation</a>,
+ but the overall interpretation of Video sources may in fact be
+ partly determined by the expected standard Video display device
+ characteristics (see <b>Viewing conditions adjustment and gamut
+ mapping</b> below for more details).<br>
+ <br>
+ To enable targeting these colorspaces, ArgyllCMS provides 5 ICC
+ profiles in the ref directory to use as source
+ colorspaces: <br>
+ <br>
+ EBU3213_PAL.icm<br>
+ <br>
+ SMPTE_RP145_NTSC.icm<br>
+ <br>
+ Rec709.icm<br>
+ <br>
+ Rec2020.icm<br>
+ <br>
+ SMPTE431_P3.icm<br>
+ <h5>6) Signal encoding</h5>
+ Typical PC display output uses full range RGB signals (0 .. 255 in 8
+ bit parlance), while typical Video encoding allows some head &
+ footroom for overshoot and sync of digitized analog signals, and
+ typically uses a 16..235 range in 8 bits. In many cases Video is
+ encoded as luma and color difference signals YCbCr (loosely known as
+ YUV as well), and this also uses a restricted range 16..235 for Y,
+ and 16..240 for Cb and Cr in 8 bit encoding. The extended gamut
+ xvYCC encoding uses 16..235 for Y, and 1..254 for Cb and Cr.<br>
+ <br>
+ The signal encoding comes into play in two situations: 1)
+ Calibrating and profiling the display, and 2) Using the resulting
+ Device Link/3DLut.<br>
+ The encoding may need to be different in these two situations,
+ either because different video source devices are being used for
+ calibration/profiling and for video playback, or because the video
+ playback system uses the Device Link/3DLut at a point in its
+ processing pipeline that requires a specific encoding.<br>
+ <br>
+ For calibration & profiling, the display will be driven by a
+ computer system so that dispcal and dispread can be used. By default
+ these programs expect to output full range RGB signals, and it is
+ assumed that either the display accepts full range signals, or that
+ the graphics card or connection path has been setup to convert the
+ full range values into Video range signals automatically or
+ manually. If this is not the case, then both dispcal and dispread
+ have a -E option that will modify them to output Video range RGB
+ values.<br>
+ <br>
+ If MadVR is the target of the calibration and profiling, then there
+ is an option to use it to display the calibration and profiling test
+ patches (<b>-d madvr</b>). In this case, MadVR should be configured
+ appropriately for full range or Video range encoding, and the -E
+ flag should <u>not</u> be used with dispcal or dispread, since
+ MadVR will be taking care of such conversions.<br>
+ <br>
+ If a calibration file was created using dispcal -E, then using it in
+ dispread will automatically trigger Video level RGB signals during
+ profiling. Any time such a Video level calibration is loaded into
+ the Graphics card VideoLUTs using dispwin, or the calibration curve
+ is converted to a 'vcgt' tag in a profile, the curve will also
+ convert full range RGB to Video range RGB. This should be kept in
+ mind so that if video playback is being performed with the
+ calibration curves installed in the Graphics card VideoLUTs, that
+ full range is converted only once to Video range (ie. In this
+ situation MadVR output should be set to full range if being played
+ back through the calibration curves in hardware, but only if dispcal
+ -E has been used). On the other hand, if the calibration curves are
+ incorporated into the DeviceLink/3dLUT, then the conversion to Video
+ levels has to be done somewhere else in the pipeline, such as using
+ MadVR video level output, or by the graphics card, etc.<br>
+ <br>
+ When creating the Device Link/3dLut, it is often necessary to
+ specify one of the video encodings so that it fits in to the
+ processing pipeline correctly. For instance the eeColor needs to
+ have input and output encoding that suits the HDMI signals passing
+ through it, typically Video Range RGB. MadVR needs Video Level RGB
+ to match the values being passed through the 3dLut at that point.<br>
+ <br>
+ There are several version of YCbCr encoding supported as well, even
+ though neither the eeColor nor the current version of MadVR need or
+ can use them at present.<br>
+ <h5>7) Black point mapping</h5>
+ <p>Video encoding assumes that the black displayed on a device is a
+ perfect black (zero light). No real device has a perfect black,
+ and if a colorimetric intent is used then certain image values
+ near black will get clipped to the display black point, loosing
+ shadow detail. To avoid this, some sort of black point mapping is
+ usually desirable. There are two mechanisms available in collink:
+ a) Custom EOTF with input and/or output black point mapping, or b)
+ using one of the smart gamut mapping intents that does black point
+ mapping (e.g. la, p, pa, ms or s).<br>
+ </p>
+ <h5>8) Viewing conditions adjustment and gamut mapping</h5>
+ <p> </p>
+ <p>In historical TV systems, there is a viewing conditions
+ adjustment being made between the bright studio conditions that TV
+ is filmed in, and the typical dim viewing environment that people
+ view it in. This is created by the difference between the encoding
+ response curve gamma of about 2.0, and a typical CRT response
+ curve gamma of 2.4. <br>
+ </p>
+ <p>In theory Rec709 defines the video encoding, but it seems in
+ practice that much video material is adjusted to look as intended
+ when displayed on a reference monitor having a display gamma of
+ somewhere between 2.2 and 2.4, viewed in a dim viewing
+ environment. The modern standard covering the display EOTF
+ (Electro-Optical Transfer Curve) is <a
+ href="http://www.itu.int/rec/R-REC-BT.1886-0-201103-I">BT.1886</a>,
+ which defines a pure power 2.4 curve with an input offset and
+ scale applied to account for the black point offset while
+ retaining dark shadow tonality. So another means of making the
+ viewing adjustment is to use the BT.1886-like EOTF for Rec709
+ encoded material. Collink supports this using the <a
+ href="collink.html#I">-I b</a>, and allows some control over the
+ degree of viewing conditions adjustment by overriding the BT.1886
+ gamma using the <a href="collink.html#Ib">-I b:g.g</a>
+ parameter. This is the <b>recommended</b> approach to start with,
+ since it gives good results with a single parameter.<br>
+ </p>
+ <p>The addition of a second optional parameter <a
+ href="file:///D:/src/argyll/doc/collink.html#Ib">-I b:p.p:g.g</a>
+ allows control over the degree of black point offset accounted for
+ as an output offset, as opposed to input offset Once the effective
+ gamma value has been chosen to suite the viewing conditions and
+ set the overall contrast for mid greys, increasing the proportion
+ of black offset accounted for in the output of the curve is a way
+ of reducing the deep shadow detail, if it is being overly
+ emphasized. </p>
+ <p> An alternate approach to making this adjustment is to take
+ advantage of the viewing conditions adjustment using the CIECAM02
+ model available in collink. Some control over the degree of
+ viewing conditions adjustment is possible by varying the viewing
+ condition parameters. </p>
+ <p>A third alternative is to combine the two approaches. The source
+ is defined as Rec709 primaries with a BT.1886-like EOTF display in
+ dim viewing conditions, and then CIECAM02 is used to adjust for
+ the actual display viewing conditions. Once again, control over
+ the degree of viewing conditions adjustment is possible by varying
+ the viewing condition parameters<br>
+ </p>
+ <p><br>
+ </p>
+ <p><b>9) Correcting for any black point inaccuracy in the display
+ profile</b><br>
+ </p>
+ <p>Some video display devices have particularly good black points,
+ and any slight raising of the black due to innacuracies in the
+ display profile near black can be objectionable. As well as using
+ the <a href="targen.html#V">targen -V flag</a> to improve
+ accuracy near black during profiling, if the display is known to
+ be well behaved (ie. that it's darkest black is actually at RGB
+ value 0,0,0), then the <a href="collink.html#b">collink -b</a>
+ flag can be used, to force the source RGB 0,0,0 to map to the
+ display 0,0,0.<br>
+ </p>
+ <h5>Putting it all together:</h5>
+ In this example we choose to create a display calibration first
+ using dispcal, and create a simple matrix profile as well:<br>
+ <br>
+ <tt>dispcal -v -o -qm -k0 -w 0.3127,0.3290 -gs -o TVmtx.icm
+ TV</tt><br>
+ <br>
+ We are targeting a D65 white point (<tt>-w 0.3127,0.3290)</tt> and
+ an sRGB response curve.<br>
+ <br>
+ If you are using the madTPG you would use:<br>
+ <br>
+ <tt>dispcal -v -d madvr -o -qm -k0 -w 0.3127,0.3290 -gs -o
+ TVmtx.icm TV</tt><br>
+ <br>
+ Then we need to create a display patch test set. We can use the
+ simple matrix to pre-condition the test patches, as this helps
+ distribute them where they will be of most benefit. If have
+ previously profiled your display, you should use that previous
+ profile, or if you decided not to do a dispcal, then the Rec709.icm
+ should be used as a substitute. Some per channel and a moderate
+ number of full spread patches is used here - more will increase
+ profiling accuracy, a smaller number will speed it up. Since the
+ video or film material is typically viewed in a darkened viewing
+ environment, and often uses a range of maximum brightnesses in
+ different scenes, the device behavior in the dark regions of its
+ response are often of great importance, and using the <a
+ href="targen.html#V">targen -V</a> parameter can help improve the
+ accuracy in this region at the expense of slightly lower accuracy in
+ lighter regions.<br>
+ <br>
+ <tt>targen -v -d3 -s30 -g100 -f1000 -cTVmtx.icm -V1.8 TV</tt><br>
+ <br>
+ The display can then be measured:<br>
+ <br>
+ <tt>dispread -v -k -Z8 TV.cal TV</tt><br>
+ <br>
+ or using madTPG:<br>
+ <br>
+ dispread -v -d madvr -K TV.cal TV<br>
+ <br>
+ and then a cLUT type ICC profile created. Since we will be using
+ collink smart linking, we minimize the B2A table size. We use the
+ default colprof -V parameter carried through from targen:<br>
+ <br>
+ <tt>colprof -v -qh -bl TV</tt><br>
+ <br>
+ Make sure you check the delta E report at the end of the profile
+ creation, to see if the sample data and profile is behaving
+ reasonably. Depending on the type of device, and the consistency of
+ the readings, average errors of 5 or less, and maximum errors of 15
+ or less would normally be expected. If errors are grossly higher
+ than this, then this is an indication that something is seriously
+ wrong with the device measurement, or profile creation.<br>
+ <br>
+ If you would like to use the display ICC profile for general color
+ managed applications, then you would compute a more complete
+ profile:<br>
+ <br>
+ <tt>colprof -v -qh TV</tt><br>
+ <br>
+ The recommended approach then is to create a Device Link that uses a
+ BT.1886 black point and viewing conditions adjustment, say one of
+ the following:<br>
+ <br>
+ <tt> collink -v -Ib:2.4 -b -G -ir Rec709.icm TV.icm
+ HD.icm # dark conditions</tt><tt><br>
+ </tt><tt> collink -v -Ib -b -G -ir
+ Rec709.icm TV.icm HD.icm # dim conditions - good
+ default</tt><tt><br>
+ </tt><tt> collink -v -Ib:2.1 -b -G -ir Rec709.icm TV.icm
+ HD.icm # mid to dim conditions</tt><tt><br>
+ </tt><tt> collink -v -Ib:2.0 -b -G -ir Rec709.icm TV.icm
+ HD.icm # mid to light conditions</tt><br>
+ <br>
+ or you could do it using pure CIECAM02 adjustment and a black point
+ mapping:<br>
+ <br>
+ <tt> collink -v -ctv -dmd -da:1 -G -ila Rec709.icm TV.icm
+ HD.icm # very dark conditions</tt><tt><br>
+ </tt><tt> collink -v -ctv -dmd -da:3 -G -ila Rec709.icm
+ TV.icm HD.icm # dim conditions</tt><tt><br>
+ </tt><tt> collink -v -ctv -dmd -da:7 -G -ila Rec709.icm
+ TV.icm HD.icm # mid to dim conditions - good default</tt><tt><br>
+ </tt><tt> collink -v -ctv -dmd -da:15 -G -ila Rec709.icm
+ TV.icm HD.icm # mid conditions</tt><br>
+ <br>
+ or using both to model a reference video display system that is
+ adapted to your viewing conditions:<br>
+ <tt><br>
+ </tt><tt> collink -v -Ib -c md -dmd -da:5 -G -ila
+ Rec709.icm TV.icm HD.icm # very dark conditions</tt><tt><br>
+ </tt><tt> collink -v -Ib -c md -dmd -da:10 -G -ila Rec709.icm
+ TV.icm HD.icm # dim conditions</tt><tt><br>
+ </tt><tt> collink -v -Ib -c md -dmd -da:18 -G -ila Rec709.icm
+ TV.icm HD.icm # mid to dark conditions</tt><tt><br>
+ </tt><tt> collink -v -Ib -c md -dmd -da:30 -G -ila Rec709.icm
+ TV.icm HD.icm # mid to dark conditions</tt><br>
+ <br>
+ None of the above examples incorporate the calibration curves, so it
+ is assumed that the calibration curves would be installed so that
+ the Video Card applies calibration, ie:<br>
+ <br>
+ <tt>dispwin TV.cal</tt><br>
+ <br>
+ or the simple matrix profile installed:<br>
+ <br>
+ <tt>dispwin -I TVmtx.icm</tt><br>
+ <br>
+ or a the more complete display profile could be installed:<br>
+ <br>
+ dispwin -I TV.icm<br>
+ <br>
+ See also <a href="dispprofloc.html">here</a> for information on how
+ to make sure the calibration is loaded on each system start. If not,
+ then you will want to incorporate the calibration in the Device
+ Link/3dlut by using collink "-a TV.cal".<br>
+ <br>
+ If the video path needs Video Level RGB encoding but does not
+ provide a means to do this, then you will want to include the <b>-E</b>
+ flag in the dispcal and dispread command lines above.<br>
+ <br>
+ Below are specific recommendation for the eeColor and MadVR that
+ include the flags to create the .3dlut and encode the input and
+ output values appropriately, but only illustrate using the
+ recommended BT.1886 black point and viewing conditions adjustments,
+ rather than illustrating CIECAM02 etc. use.<br>
+ <br>
+ For faster exploration of different collink option, you could omit
+ the "colprof -bl" option, and use collink "-g" instead of "-G",
+ since this<br>
+ will greatly speed up collink. Once you are happy with the link
+ details, you can then generate a higher quality link/3dLut using
+ "collink -G ..".<br>
+ <br>
+ You can also increase the precision of the device profile by
+ increasing the number of test patches measured (ie. up to a few
+ thousand, depending on how long you are prepared to wait for the
+ measurement to complete, and how stable your display and instrument
+ are).<br>
+ <br>
+ Alternatives to relative colorimetric rendering ("-i r") or
+ luminance matched appearance ("-i la") used in the examples above
+ and below, are, perceptual ("-i p") which will ensure that the
+ source gamut is compressed rather than clipped by the display, or
+ even a saturation rendering ("-i ms"), which will expand the gamut
+ of the source to the full range of the output.<br>
+ <br>
+ <br>
+ <b>eeColor</b><br>
+ <br>
+ For PC use, where the encoding is full range RGB:<br>
+ <br>
+ <tt>collink -v -3e -Ib -b -G -ir -a TV.cal Rec709.icm TV.icm
+ HD.icm </tt><br>
+ <br>
+ For correct operation both the 3DLut HD.txt and the per channel
+ input curves HD-first1dred.txt, HD-first1dgreen.txt and
+ HD-first1dblue.txt. the latter by copying them over the default
+ input curve files uploaded by the TruVue application.<br>
+ <br>
+ See <a
+ href="http://www.avsforum.com/t/1464890/eecolor-processor-argyllcms"><http://www.avsforum.com/t/1464890/eecolor-processor-argyllcms></a>
+ for some more details.<br>
+ <br>
+ Where the eeColor is connected from a Video source using HDMI, it
+ will probably be processing TV RGB levels, or YCbCr encoded signals
+ that it converts to/from RGB internally, so<br>
+ <br>
+ <tt>collink -v -3e -et -Et -Ib -b -G -ir -a TV.cal
+ Rec709.icm TV.icm HD.icm </tt><br>
+ <br>
+ in this case just the HD.txt file needs installing on the eeColor,
+ but make sure that the original linear "first1*.txt files are
+ re-installed, or install the ones generated by collink, which will
+ be linear for -e t mode.<br>
+ <br>
+ <b>MadVR</b><br>
+ <br>
+ MadVR 0.86.9 or latter has a number of features to support accurate
+ profiling and calibration, and is the recommended version to
+ use. It converts from the media colorspace to the 3dLut input
+ space automatically with the type of source being played, but has
+ configuration for to 5 3dLuts, each one optimized for a particular
+ source color space. The advantage of building and installing several
+ 3dLuts is that unnecessary gamut clipping can be avoided.<br>
+ <br>
+ If you are just building one 3dLut then Rec709 source is a good one
+ to pick.<br>
+ <br>
+ If you want to share the VideoLUT calibration curves between your
+ normal desktop and MadVR, then it is recommended that you install
+ the display ICC profile and use the -H option:<br>
+ <br>
+ <tt> collink -v -3m -et -Et -Ib -b -G -ir -H
+ TV.cal Rec709.icm TV.icm HD.icm</tt><tt><br>
+ </tt><tt> </tt><tt><br>
</tt><tt> collink -v -3m -et -Et -Ib -b -G -ir </tt><tt><tt>-H @@ -3805,11 +3742,9 @@ a - - - - TV.cal </tt>EBU3213_PAL.icm TV.icm SD_PAL.icm</tt><tt><br> - </tt><tt> </tt><tt><br> +
+ TV.cal </tt>EBU3213_PAL.icm TV.icm SD_PAL.icm</tt><tt><br>
+ </tt><tt> </tt><tt><br>
</tt><tt> collink -v -3m -et -Et -Ib -b -G -ir </tt><tt><tt>-H @@ -3833,18 +3768,16 @@ a - - - - TV.cal </tt>SMPTE_RP145_NTSC.icm TV.icm SD_NTSC.icm</tt><br> - <br> - For best quality it is better to let MadVR apply the calibration - curves using dithering, and allow it to set the graphics card to - linear by using the -a option:<br> - <br> - <tt> collink -v -3m -et -Et -Ib -b -G -ir -a - TV.cal Rec709.icm TV.icm HD.icm</tt><tt><br> - </tt><tt> </tt><tt><br> +
+ TV.cal </tt>SMPTE_RP145_NTSC.icm TV.icm SD_NTSC.icm</tt><br>
+ <br>
+ For best quality it is better to let MadVR apply the calibration
+ curves using dithering, and allow it to set the graphics card to
+ linear by using the -a option:<br>
+ <br>
+ <tt> collink -v -3m -et -Et -Ib -b -G -ir -a
+ TV.cal Rec709.icm TV.icm HD.icm</tt><tt><br>
+ </tt><tt> </tt><tt><br>
</tt><tt> collink -v -3m -et -Et -Ib -b -G -ir </tt><tt><tt>-a @@ -3868,11 +3801,9 @@ a - - - - TV.cal </tt>EBU3213_PAL.icm TV.icm SD_PAL.icm</tt><tt><br> - </tt><tt> </tt><tt><br> +
+ TV.cal </tt>EBU3213_PAL.icm TV.icm SD_PAL.icm</tt><tt><br>
+ </tt><tt> </tt><tt><br>
</tt><tt> collink -v -3m -et -Et -Ib -b -G -ir </tt><tt><tt>-a @@ -3896,184 +3827,182 @@ a - - - - TV.cal </tt>SMPTE_RP145_NTSC.icm TV.icm SD_NTSC.icm</tt><br> - <br> - the consequence though is that the appearance of other application - will shift when MadVR is using the 3dLut and loading the calibration - curves.<br> - <br> - The 3dLut can be used by opening the MadVR settings dialog, - selecting "calibration" and then selecting "calibrate this display - by using an external 3DLUT file", and then using the file dialog to - use it.<br> - <br> - If neither the -a no -H options are used, then no calibration curves - will be appended to the 3dLut, and MadVR will not change the - VideoLUTs when that 3dLut is in use. It is then up to you to manage - the graphics card VideoLUTs in some other fashion.<tt><br> - <br> - </tt> - <hr size="2" width="100%"><br> - <h3><a name="TV2"></a>Verifying Video Calibration</h3> - <p>Often it is desirable to verify the results of a video - calibration and profile, and the following gives an outline of how - to use ArgyllCMS tools to do this. It is only possible to expect - perfect verification if a colorimetric intent was used during - linking - currently it's not possible to exactly verify a - perceptual or CIECAM02 viewing condition adjusted link.<br> - <br> - </p> - <p>The first step is to create a set of test points. This is - essentially the same as creating a set of test points for the - purposes of profiling, although it is best not to create exactly - the same set, so as to explore the colorspace at different - locatioins. For the purposes here, we'll actually create a regular - grid test set, since this makes it easier to visualize the - results, although a less regular set would probably be better for - numerical evaluation:<br> - </p> - <p> targen -v -d3 -e1 -m6 -f0 -W verify<br> - </p> - <p>We make sure there is at least one white patch usin g -e1, a 20% - increment grid using -m6, no full spread patches, and create an - X3DOM 3d visualization of the point set using the -W flag. It is - good to take a look at the verifyd.x3d.html file using a Web - browser. You may want to create several test sets that look at - particular aspects, ie. neutral axis response, pure colorant - responses, etc.<br> - </p> - <p>Next we create a reference file by simulating the expected - response of the perfect video display system. Assuming the collink - options were "-et -Et -Ib -G -ir Rec709.icm TV.icm HD.icm" then we - would:<tt><tt><br> - </tt></tt></p> - <p><tt><tt> copy verify.ti1 ref.ti1<br> - fakeread -v -b -Z8 TV.icm Rec709.icm ref<br> - </tt></tt></p> - <p>You should adjust the parameters as necessary, so that the - reference matches the link options. For instance, if your link - options included "-I b:0.2:2.15" then the equivalent fakeread - option "-b 0.2:2.15:TV.icm" should be used, etc.<br> - </p> - <hr size="2" width="20%"> - <p>A sanity check we can make at this point is to see what the - expected result of the profiling & calibration will be, by - simulating the reproduction of this test set:<br> - </p> - <p><tt> copy verify.ti1 checkA.ti1</tt><tt><br> - fakeread -v -et -Z8 -p HD.icm -Et TV.icm checkA<br> - </tt></p> - <p>If you used collink -a, then the calibration incorporated in the - device link needs to be undone to match what the display profile - expects:</p> - <p><tt> fakeread -v -et -Z8 -p HD.icm -Et -K TV.cal TV.icm - checkA</tt></p> - <p><tt>and then you can verify:<br> - </tt></p> - <p><tt> colverify -v -n -w -x ref.ti3 checkA.ti3<br> - </tt></p> - <p>If you have targeted some other white point rather than video D65 - for the display, then use the -N flag instead of -n to align the - white points. [ Note that there can be some small discrepancies in - this case in some parts of the color space if a CIECAM02 linking - intent was used, due to the slightly different chromatic - adaptation algorithm it uses compared to the one used by verify to - match the white points.]<tt><br> - </tt></p> - <p><tt> v</tt><tt>erify -v -N -w -x ref.ti3 checkA.ti3</tt><br> - </p> - <p>This will give a numerical report of the delta E's, and also - generate an X3DOM plot of the errors in L*a*b* space. The - important thing is to take a look at the checkA.x3d.html file, to - see if gamut clipping is occurring - this is the case if the large - error vectors are on the sides or top of the gamut. Note that the - perfect cube device space values become a rather distorted cube - like shape in the perceptual L*a*b* space. If the vectors are - small in the bulk of the space, then this indicates that the link - is likely to be doing the right thing in making the display - emulate the video colorspace with a BT.1886 like black point - adjustment. You could also check just the in gamut test points - using:<br> - </p> - <p><tt> v</tt><tt>erify -v -N -w -x -L TV.icm ref.ti3 - checkA.ti3<br> - <br> - </tt></p> - <hr size="2" width="20%"> - <p>You can explicitly compare the gamuts of your video space and - your display using the gamut tools:<br> - </p> - <p><tt> iccgamut -ff -ia Rec709</tt><tt><br> - </tt><tt> iccgamut -ff -ia TV.icm</tt><tt><br> - </tt><tt> viewgam -i Rec709.gam TV.gam gamuts</tt><br> - </p> - <p>and look at the gamuts.x3d.html file, as well as taking notice of - % of the video volume that the display intersects. The X3DOM solid - volume will be the video gamut, while the wire frame is the - display gamut. If you are not targetting D65 with your display, - you should use iccgamut <b>-ir</b> instead of <b>-ia</b>, so as - to align the white points.<br> - </p> - <hr size="2" width="20%"> - <p>The main verification check is to actually measure the display - response and compare it against the reference. Make sure the - display is setup as you would for video playback and then use - dispread:<br> - </p> - <p><tt> copy verify.ti1 checkB.ti1</tt><tt><br> - </tt><tt> dispread -v -Z8 checkB</tt><br> - </p> - <p>You would add any other options needed (such as <b>-y</b> etc.) - to set your instrument up properly. If you are using madTPG, then - configure madVR to use the 3dLut you want to measure as the - default, and also use the dispread -V flag to make sure that the - 3dLut is being used for the measurements: [<b>Note</b> that if the - version of MadVR you are using does not have radio buttons in its - calibration setup to indicate a default 3dLut, then the 3dLut - under test should be the only one set - all others should be - blank. ]<br> - </p> - <p><tt> dispread -v -d madvr -V checkB</tt><br> - </p> - <p>Verify the same way as above:<br> - </p> - <p><tt> v</tt><tt>erify -v -n -w -x ref.ti3 checkB.ti3<br> - </tt></p> - <p>If your display does not cover the full gamut of your video - source, the errors are probably dominated by out of gamut colors. - You can verify just the in gamut test values by asking verify to - skip them, and this will give a better notion of the actual device - link and calibration accuracy:<tt><br> - </tt></p> - <p><tt> v</tt><tt>erify -v -n -w -x -L TV.icm ref.ti3 - checkB.ti3</tt></p> - <p><br> - </p> - <p> <br> - </p> - <p><br> - <br> - </p> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - <br> - </body> -</html> +
+ TV.cal </tt>SMPTE_RP145_NTSC.icm TV.icm SD_NTSC.icm</tt><br>
+ <br>
+ the consequence though is that the appearance of other application
+ will shift when MadVR is using the 3dLut and loading the calibration
+ curves.<br>
+ <br>
+ The 3dLut can be used by opening the MadVR settings dialog,
+ selecting "calibration" and then selecting "calibrate this display
+ by using an external 3DLUT file", and then using the file dialog to
+ use it.<br>
+ <br>
+ If neither the -a no -H options are used, then no calibration curves
+ will be appended to the 3dLut, and MadVR will not change the
+ VideoLUTs when that 3dLut is in use. It is then up to you to manage
+ the graphics card VideoLUTs in some other fashion.<tt><br>
+ <br>
+ </tt>
+ <hr size="2" width="100%"><br>
+ <h3><a name="TV2"></a>Verifying Video Calibration</h3>
+ <p>Often it is desirable to verify the results of a video
+ calibration and profile, and the following gives an outline of how
+ to use ArgyllCMS tools to do this. It is only possible to expect
+ perfect verification if a colorimetric intent was used during
+ linking - currently it's not possible to exactly verify a
+ perceptual or CIECAM02 viewing condition adjusted link.<br>
+ <br>
+ </p>
+ <p>The first step is to create a set of test points. This is
+ essentially the same as creating a set of test points for the
+ purposes of profiling, although it is best not to create exactly
+ the same set, so as to explore the colorspace at different
+ locatioins. For the purposes here, we'll actually create a regular
+ grid test set, since this makes it easier to visualize the
+ results, although a less regular set would probably be better for
+ numerical evaluation:<br>
+ </p>
+ <p> targen -v -d3 -e1 -m6 -f0 -W verify<br>
+ </p>
+ <p>We make sure there is at least one white patch usin g -e1, a 20%
+ increment grid using -m6, no full spread patches, and create an
+ X3DOM 3d visualization of the point set using the -W flag. It is
+ good to take a look at the verifyd.x3d.html file using a Web
+ browser. You may want to create several test sets that look at
+ particular aspects, ie. neutral axis response, pure colorant
+ responses, etc.<br>
+ </p>
+ <p>Next we create a reference file by simulating the expected
+ response of the perfect video display system. Assuming the collink
+ options were "-et -Et -Ib -G -ir Rec709.icm TV.icm HD.icm" then we
+ would:<tt><tt><br>
+ </tt></tt></p>
+ <p><tt><tt> copy verify.ti1 ref.ti1<br>
+ fakeread -v -b -Z8 TV.icm Rec709.icm ref<br>
+ </tt></tt></p>
+ <p>You should adjust the parameters as necessary, so that the
+ reference matches the link options. For instance, if your link
+ options included "-I b:0.2:2.15" then the equivalent fakeread
+ option "-b 0.2:2.15:TV.icm" should be used, etc.<br>
+ </p>
+ <hr size="2" width="20%">
+ <p>A sanity check we can make at this point is to see what the
+ expected result of the profiling & calibration will be, by
+ simulating the reproduction of this test set:<br>
+ </p>
+ <p><tt> copy verify.ti1 checkA.ti1</tt><tt><br>
+ fakeread -v -et -Z8 -p HD.icm -Et TV.icm checkA<br>
+ </tt></p>
+ <p>If you used collink -a, then the calibration incorporated in the
+ device link needs to be undone to match what the display profile
+ expects:</p>
+ <p><tt> fakeread -v -et -Z8 -p HD.icm -Et -K TV.cal TV.icm
+ checkA</tt></p>
+ <p><tt>and then you can verify:<br>
+ </tt></p>
+ <p><tt> colverify -v -n -w -x ref.ti3 checkA.ti3<br>
+ </tt></p>
+ <p>If you have targeted some other white point rather than video D65
+ for the display, then use the -N flag instead of -n to align the
+ white points. [ Note that there can be some small discrepancies in
+ this case in some parts of the color space if a CIECAM02 linking
+ intent was used, due to the slightly different chromatic
+ adaptation algorithm it uses compared to the one used by verify to
+ match the white points.]<tt><br>
+ </tt></p>
+ <p><tt> v</tt><tt>erify -v -N -w -x ref.ti3 checkA.ti3</tt><br>
+ </p>
+ <p>This will give a numerical report of the delta E's, and also
+ generate an X3DOM plot of the errors in L*a*b* space. The
+ important thing is to take a look at the checkA.x3d.html file, to
+ see if gamut clipping is occurring - this is the case if the large
+ error vectors are on the sides or top of the gamut. Note that the
+ perfect cube device space values become a rather distorted cube
+ like shape in the perceptual L*a*b* space. If the vectors are
+ small in the bulk of the space, then this indicates that the link
+ is likely to be doing the right thing in making the display
+ emulate the video colorspace with a BT.1886 like black point
+ adjustment. You could also check just the in gamut test points
+ using:<br>
+ </p>
+ <p><tt> v</tt><tt>erify -v -N -w -x -L TV.icm ref.ti3
+ checkA.ti3<br>
+ <br>
+ </tt></p>
+ <hr size="2" width="20%">
+ <p>You can explicitly compare the gamuts of your video space and
+ your display using the gamut tools:<br>
+ </p>
+ <p><tt> iccgamut -ff -ia Rec709</tt><tt><br>
+ </tt><tt> iccgamut -ff -ia TV.icm</tt><tt><br>
+ </tt><tt> viewgam -i Rec709.gam TV.gam gamuts</tt><br>
+ </p>
+ <p>and look at the gamuts.x3d.html file, as well as taking notice of
+ % of the video volume that the display intersects. The X3DOM solid
+ volume will be the video gamut, while the wire frame is the
+ display gamut. If you are not targetting D65 with your display,
+ you should use iccgamut <b>-ir</b> instead of <b>-ia</b>, so as
+ to align the white points.<br>
+ </p>
+ <hr size="2" width="20%">
+ <p>The main verification check is to actually measure the display
+ response and compare it against the reference. Make sure the
+ display is setup as you would for video playback and then use
+ dispread:<br>
+ </p>
+ <p><tt> copy verify.ti1 checkB.ti1</tt><tt><br>
+ </tt><tt> dispread -v -Z8 checkB</tt><br>
+ </p>
+ <p>You would add any other options needed (such as <b>-y</b> etc.)
+ to set your instrument up properly. If you are using madTPG, then
+ configure madVR to use the 3dLut you want to measure as the
+ default, and also use the dispread -V flag to make sure that the
+ 3dLut is being used for the measurements: [<b>Note</b> that if the
+ version of MadVR you are using does not have radio buttons in its
+ calibration setup to indicate a default 3dLut, then the 3dLut
+ under test should be the only one set - all others should be
+ blank. ]<br>
+ </p>
+ <p><tt> dispread -v -d madvr -V checkB</tt><br>
+ </p>
+ <p>Verify the same way as above:<br>
+ </p>
+ <p><tt> v</tt><tt>erify -v -n -w -x ref.ti3 checkB.ti3<br>
+ </tt></p>
+ <p>If your display does not cover the full gamut of your video
+ source, the errors are probably dominated by out of gamut colors.
+ You can verify just the in gamut test values by asking verify to
+ skip them, and this will give a better notion of the actual device
+ link and calibration accuracy:<tt><br>
+ </tt></p>
+ <p><tt> v</tt><tt>erify -v -n -w -x -L TV.icm ref.ti3
+ checkB.ti3</tt></p>
+ <p><br>
+ </p>
+ <p> <br>
+ </p>
+ <p><br>
+ <br>
+ </p>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ <br>
+ </body>
+</html>
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