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-<!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=ISO-8859-1">
- </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>&nbsp;&nbsp;&nbsp; <a href="#PM1a">Checking you can access your
- display<br>
- </a></h4>
- <h4>&nbsp;&nbsp;&nbsp; <a href="#PM1b">Adjusting and Calibrating a
- displays</a></h4>
- <h4>&nbsp;&nbsp;&nbsp; <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>&nbsp;&nbsp;&nbsp; <a href="#PM2">Creating display test values</a></h4>
- <h4> &nbsp;&nbsp;&nbsp; <a href="#PM3">Taking readings from a
- display</a></h4>
- <h4> &nbsp;&nbsp;&nbsp; <a href="#PM4">Creating a display profile</a></h4>
- <h4> &nbsp;&nbsp;&nbsp; <span style="text-decoration: underline;"></span><a
- href="#PM5">Installing a display profile</a></h4>
- <h4> &nbsp;&nbsp;&nbsp; <span style="text-decoration: underline;"></span><a
- href="#PM6">Expert tips when measuring displays</a></h4>
- <h4>&nbsp;&nbsp;&nbsp; <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>&nbsp;&nbsp;&nbsp; <a href="#PS2">Types of test charts</a></h4>
- <h4>&nbsp;&nbsp;&nbsp; <a href="#PS3">Taking readings from a
- scanner</a></h4>
- <h4>&nbsp;&nbsp;&nbsp; <a href="#PS4">Creating a scanner profile</a></h4>
- <h4><br>
- <a href="#PP1">Profiling Printers</a></h4>
- <h4> &nbsp;&nbsp;&nbsp; <a href="#PP2">Creating a print profile
- test chart</a></h4>
- <h4> &nbsp;&nbsp;&nbsp; <a href="Scenarios.html#PP2b">Printing a
- print profile test chart</a></h4>
- <h4> &nbsp;&nbsp;&nbsp; <a href="#PP3">Reading a print test chart
- using an instrument</a></h4>
- <h4> &nbsp;&nbsp;&nbsp; <a href="#PP4">Reading a print test chart
- using a scanner</a></h4>
- <h4> </h4>
- <h4>&nbsp;&nbsp;&nbsp; <a href="#PP5">Creating a printer profile<br>
- </a></h4>
- <h4>&nbsp;&nbsp;&nbsp; <a href="#PP6">Choosing a black generation
- curve</a></h4>
- <br>
- <h4><a href="Scenarios.html#PC1">Calibrating Printers</a></h4>
- <h4> &nbsp;&nbsp;&nbsp; <a href="Scenarios.html#PC2">Calibrated
- print workflows</a></h4>
- <h4> &nbsp;&nbsp;&nbsp; <a href="Scenarios.html#PC3">Creating a
- print calibration test chart</a></h4>
- <h4> </h4>
- <h4>&nbsp;&nbsp;&nbsp; <a href="Scenarios.html#PC4">Creating a
- printer calibration<br>
- </a></h4>
- <h4>&nbsp;&nbsp;&nbsp; <a href="Scenarios.html#PC5">Using a printer
- calibration</a></h4>
- <h4>&nbsp;&nbsp;&nbsp; <a href="#PC6">How profile ink limits are
- handled when calibration is being used<br>
- </a></h4>
- <h4><br>
- <a href="#LP1">Linking Profiles</a></h4>
- <h4><br>
- <a href="#TR1">Transforming colorspaces of raster files</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.&nbsp;
- Adjustment and calibration are prior steps to profiling, in which
- the display is adjusted using it's screen controls,&nbsp; and then
- per channel lookup tables are created to make it meet a well behaved
- response of the desired type. The&nbsp; 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>&nbsp;&nbsp;&nbsp; <a href="#PM1a">Checking you can access your
+ display<br>
+ </a></h4>
+ <h4>&nbsp;&nbsp;&nbsp; <a href="#PM1b">Adjusting and Calibrating a
+ displays</a></h4>
+ <h4>&nbsp;&nbsp;&nbsp; <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>&nbsp;&nbsp;&nbsp; <a href="#PM2">Creating display test values</a></h4>
+ <h4> &nbsp;&nbsp;&nbsp; <a href="#PM3">Taking readings from a
+ display</a></h4>
+ <h4> &nbsp;&nbsp;&nbsp; <a href="#PM4">Creating a display profile</a></h4>
+ <h4> &nbsp;&nbsp;&nbsp; <span style="text-decoration: underline;"></span><a
+ href="#PM5">Installing a display profile</a></h4>
+ <h4> &nbsp;&nbsp;&nbsp; <span style="text-decoration: underline;"></span><a
+ href="#PM6">Expert tips when measuring displays</a></h4>
+ <h4>&nbsp;&nbsp;&nbsp; <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>&nbsp;&nbsp;&nbsp; <a href="#PS2">Types of test charts</a></h4>
+ <h4>&nbsp;&nbsp;&nbsp; <a href="#PS3">Taking readings from a
+ scanner</a></h4>
+ <h4>&nbsp;&nbsp;&nbsp; <a href="#PS4">Creating a scanner profile</a></h4>
+ <h4><br>
+ <a href="#PP1">Profiling Printers</a></h4>
+ <h4> &nbsp;&nbsp;&nbsp; <a href="#PP2">Creating a print profile
+ test chart</a></h4>
+ <h4> &nbsp;&nbsp;&nbsp; <a href="Scenarios.html#PP2b">Printing a
+ print profile test chart</a></h4>
+ <h4> &nbsp;&nbsp;&nbsp; <a href="#PP3">Reading a print test chart
+ using an instrument</a></h4>
+ <h4> &nbsp;&nbsp;&nbsp; <a href="#PP4">Reading a print test chart
+ using a scanner</a></h4>
+ <h4> </h4>
+ <h4>&nbsp;&nbsp;&nbsp; <a href="#PP5">Creating a printer profile<br>
+ </a></h4>
+ <h4>&nbsp;&nbsp;&nbsp; <a href="#PP6">Choosing a black generation
+ curve</a></h4>
+ <br>
+ <h4><a href="Scenarios.html#PC1">Calibrating Printers</a></h4>
+ <h4> &nbsp;&nbsp;&nbsp; <a href="Scenarios.html#PC2">Calibrated
+ print workflows</a></h4>
+ <h4> &nbsp;&nbsp;&nbsp; <a href="Scenarios.html#PC3">Creating a
+ print calibration test chart</a></h4>
+ <h4> </h4>
+ <h4>&nbsp;&nbsp;&nbsp; <a href="Scenarios.html#PC4">Creating a
+ printer calibration<br>
+ </a></h4>
+ <h4>&nbsp;&nbsp;&nbsp; <a href="Scenarios.html#PC5">Using a printer
+ calibration</a></h4>
+ <h4>&nbsp;&nbsp;&nbsp; <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>
+ <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.&nbsp;
+ Adjustment and calibration are prior steps to profiling, in which
+ the display is adjusted using it's screen controls,&nbsp; and then
+ per channel lookup tables are created to make it meet a well behaved
+ response of the desired type. The&nbsp; 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
- 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
@@ -157,330 +195,368 @@
- -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&nbsp;
- 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,&nbsp; 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,&nbsp; 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, &nbsp;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>
- &nbsp;<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>
- &nbsp;<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 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&nbsp; <span style="font-weight: bold;">Microsoft&nbsp;Color&nbsp;Control&nbsp;Panel&nbsp;Applet&nbsp;for&nbsp;Windows&nbsp;XP</span>
- available for download from Microsoft to do this, but&nbsp;<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-&gt;Programs-&gt;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&nbsp;
+ 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,&nbsp; 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,&nbsp; 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, &nbsp;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>
+ &nbsp;<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>
+ &nbsp;<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&nbsp; <span style="font-weight: bold;">Microsoft&nbsp;Color&nbsp;Control&nbsp;Panel&nbsp;Applet&nbsp;for&nbsp;Windows&nbsp;XP</span>
+ available for download from Microsoft to do this, but&nbsp;<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-&gt;Programs-&gt;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>&nbsp;
@@ -490,20 +566,57 @@
- (<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,&nbsp; (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,&nbsp; (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
@@ -512,117 +625,154 @@
- 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>&nbsp; 1) Don't attempt to calibrate, just profile the display.<br>
- &nbsp; 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>&nbsp;2a) Use dispcal to create a calibration and a quick profile
- that incorporates the calibration into the profile.<br>
- &nbsp;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>
- &nbsp;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>
- &nbsp;&nbsp;&nbsp; <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>
- &nbsp;&nbsp;&nbsp; <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
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ 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>&nbsp; 1) Don't attempt to calibrate, just profile the display.<br>
+ &nbsp; 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>&nbsp;2a) Use dispcal to create a calibration and a quick profile
+ that incorporates the calibration into the profile.<br>
+ &nbsp;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>
+ &nbsp;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>
+ &nbsp;&nbsp;&nbsp; <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>
+ &nbsp;&nbsp;&nbsp; <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
@@ -632,17 +782,54 @@
- 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>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ 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
@@ -652,13 +839,50 @@
- HCT</a> :<br>
- <br>
- <img alt="HutchColor HCT" src="HCT.jpg" style="width: 182px; height:
- 140px;"><br>
- <br>
- <br>
- and <a
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ HCT</a> :<br>
+ <br>
+ <img alt="HutchColor HCT" src="HCT.jpg" style="width: 182px; height:
+ 140px;"><br>
+ <br>
+ <br>
+ and <a
href="http://www.christophe-metairie-photographie.com/eng%20digital%20target.html">Christophe
@@ -668,7 +892,44 @@ href="http://www.christophe-metairie-photographie.com/eng%20digital%20target.htm
- M&eacute;tairie's Digital TargeT 003</a> and <a
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ Métairie's Digital TargeT 003</a> and <a
href="http://www.christophe-metairie-photographie.com/eng%20digital%20target.html">Christophe
@@ -678,12 +939,49 @@ href="http://www.christophe-metairie-photographie.com/eng%20digital%20target.htm
- M&eacute;tairie's Digital Target - 3</a> :<br>
- <br>
- <img alt="CMP_DT_003" src="CMP_DT_003.jpg" style="width: 186px;
- height: 141px;">&nbsp; <img style="width: 203px; height: 140px;"
- alt="CMP_Digital_Target-3" src="CMP_Digital_Target-3.jpg"><br>
- <br>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ Métairie's Digital Target - 3</a> :<br>
+ <br>
+ <img alt="CMP_DT_003" src="CMP_DT_003.jpg" style="width: 186px;
+ height: 141px;">&nbsp; <img style="width: 203px; height: 140px;"
+ alt="CMP_Digital_Target-3" src="CMP_Digital_Target-3.jpg"><br>
+ <br>
and the <a href="http://www.silverfast.com/show/dc-targets/en.html">LaserSoft
@@ -693,106 +991,217 @@ href="http://www.christophe-metairie-photographie.com/eng%20digital%20target.htm
- 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
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ 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
- 201</a>:&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; <a
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ 201</a>:&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; <a
href="http://www.qpcard.com/en_b2c/color-reference-cards/instant-camera-raw-profiling-with-qpcard-202.html">QPcard
- 202</a>:<br>
- <br>
- <img style=" width: 41px; height: 141px;" alt="QPCard201"
- src="QPcard201.jpg">&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;
- &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; <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&nbsp; 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&nbsp;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>
- &nbsp;&nbsp; <a href="chartread.html">chartread</a> -n -a
- 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">&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;
+ &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; <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&nbsp; 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&nbsp;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>
+ &nbsp;&nbsp; <a href="chartread.html">chartread</a> -n -a
+ 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
@@ -801,78 +1210,119 @@ 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.<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>
- &nbsp;&nbsp;&nbsp;&nbsp; <a href="txt2ti3.html">txt2ti3</a>
- ColorCheckerSG.txt ColorCheckerSG<br>
- &nbsp;&nbsp;&nbsp;&nbsp; <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,&nbsp; making use of the chart reference file <span
- style="font-weight: bold;">ref/i1_RGB_Scan_1.4.ti2</span>:<br>
- &nbsp;&nbsp;&nbsp; <a href="chartread.html">chartread</a> -n -a
- 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 M&eacute;tairie'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 M&eacute;tairie's Digital Target-3 chart with
- 570 patches, the <span style="font-weight: bold;">ref/CMP_Digital_Target-3.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
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ 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>
+ &nbsp;&nbsp;&nbsp;&nbsp; <a href="txt2ti3.html">txt2ti3</a>
+ ColorCheckerSG.txt ColorCheckerSG<br>
+ &nbsp;&nbsp;&nbsp;&nbsp; <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,&nbsp; making use of the chart reference file <span
+ style="font-weight: bold;">ref/i1_RGB_Scan_1.4.ti2</span>:<br>
+ &nbsp;&nbsp;&nbsp; <a href="chartread.html">chartread</a> -n -a
+ 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-3 chart with 570
+ patches, the <span style="font-weight: bold;">ref/CMP_Digital_Target-3.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&nbsp; the <a href="cht_format.html">.cht_format
@@ -881,398 +1331,439 @@ 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),&nbsp; 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 profile is behaving reasonably.<br>
- <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
- &nbsp;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 &nbsp;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 &amp; 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>
- &nbsp;<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>
- &nbsp;<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&nbsp; 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>
- &nbsp;<a href="targen.html#d">-d2</a> <a href="targen.html#f">-f1053</a>
- <a href="targen.html#c">-c OldPrinterA</a>&nbsp;<a
- href="targen.html#p1">PrinterA</a><br>
- <br>
- <a href="targen.html">targen</a> <a href="targen.html#v">-v</a>
- &nbsp;<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>
- &nbsp;<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>
- &nbsp;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),&nbsp; 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
+ &nbsp;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 &nbsp;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 &amp; 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>
+ &nbsp;<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>
+ &nbsp;<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&nbsp; 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>
+ &nbsp;<a href="targen.html#d">-d2</a> <a href="targen.html#f">-f1053</a>
+ <a href="targen.html#c">-c OldPrinterA</a>&nbsp;<a
+ href="targen.html#p1">PrinterA</a><br>
+ <br>
+ <a href="targen.html">targen</a> <a href="targen.html#v">-v</a>
+ &nbsp;<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>
+ &nbsp;<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>
+ &nbsp;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
@@ -1282,97 +1773,134 @@ 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.).&nbsp; 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 &amp; B), while
- a reflective print, will have subtractive primaries (C, M, Y &amp;
- 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).&nbsp; 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.).&nbsp; 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 &amp; B), while
+ a reflective print, will have subtractive primaries (C, M, Y &amp;
+ 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).&nbsp; 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
@@ -1383,69 +1911,113 @@ 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>
- <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&nbsp; 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>
+ 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&nbsp; 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>),
@@ -1454,406 +2026,443 @@ 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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; (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&nbsp; how the minimum black is zero up to 93% of the
- white-&gt;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-&gt;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&nbsp; 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.
- &nbsp;
- <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>
- &nbsp;<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>
- &nbsp;<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&nbsp; <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>
- &nbsp; <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>
- &nbsp; <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>
- &nbsp; <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>
- &nbsp; <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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; (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&nbsp; how the minimum black is zero up to 93% of the
+ white-&gt;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-&gt;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&nbsp; 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.
+ &nbsp;
+ <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>
+ &nbsp;<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>
+ &nbsp;<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&nbsp; <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>
+ &nbsp; <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>
+ &nbsp; <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>
+ &nbsp; <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>
+ &nbsp; <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>
&nbsp;&nbsp;&nbsp; <a href="printtarg.html#K">printtarg</a>&nbsp;&nbsp;&nbsp;&nbsp;
To
apply
@@ -1871,7 +2480,44 @@ chart,
- and/or to have it included in .ti3 file.<br>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ and/or to have it included in .ti3 file.<br>
&nbsp;&nbsp;&nbsp; <a href="cctiff.html#p2">cctiff</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
To
apply
@@ -1889,7 +2535,44 @@ an
- image file.<br>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ image file.<br>
&nbsp;&nbsp;&nbsp; <a href="applycal.html#p1">applycal</a>&nbsp;&nbsp;&nbsp;&nbsp;
@@ -1899,7 +2582,44 @@ an
- To incorporate calibration into an ICC profile.<br>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ To incorporate calibration into an ICC profile.<br>
&nbsp;&nbsp;&nbsp; <a href="chartread.html#I">chartread</a>&nbsp;&nbsp;
To
override
@@ -1917,261 +2637,1046 @@ 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>
- &nbsp;&nbsp;&nbsp; <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>
- &nbsp;&nbsp;&nbsp; <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>
- &nbsp;&nbsp;&nbsp; <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>
- &nbsp;&nbsp;&nbsp; <a href="cctiff.html">cctiff</a> <a
- href="cctiff.html#p1">Source2Destination.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>
- or<br>
- &nbsp;&nbsp;&nbsp; <a href="cctiff.html">cctiff</a> <a
- href="cctiff.html#p1">Source2Destination.icm</a> <a
- href="cctiff.html#p2">PrinterA_c.cal</a> <a href="cctiff.html#p3">infile.jpg</a>
- <a href="cctiff.html#p4">outfile.jpg</a><br>
- <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>
- <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>
- <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="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>&nbsp;<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>
- &nbsp;
- <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>&nbsp; <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>&nbsp; <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>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- <br>
- </body>
-</html>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ 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>
+ &nbsp;&nbsp;&nbsp; <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>
+ &nbsp;&nbsp;&nbsp; <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>
+ &nbsp;&nbsp;&nbsp; <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>
+ &nbsp;&nbsp;&nbsp; <a href="cctiff.html">cctiff</a> <a
+ href="cctiff.html#p1">Source2Destination.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>
+ or<br>
+ &nbsp;&nbsp;&nbsp; <a href="cctiff.html">cctiff</a> <a
+ href="cctiff.html#p1">Source2Destination.icm</a> <a
+ href="cctiff.html#p2">PrinterA_c.cal</a> <a href="cctiff.html#p3">infile.jpg</a>
+ <a href="cctiff.html#p4">outfile.jpg</a><br>
+ <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>
+ <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>
+ <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="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>&nbsp;<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>
+ &nbsp;
+ <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>&nbsp; <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>&nbsp; <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). 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 "-d madvr" in dispcal, dispread and dispwin.
+ Leave the MadTPG "VideoLUT" and "3dluts" buttons in their
+ default&nbsp; (enabled) state, as the various tools will
+ automatically take care of disabling the 3dLut and/or calibration
+ curves as needed.<br>
+ <h5>2) White point calibration &amp; 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 &amp; 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
+
+
+
+ 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&nbsp; 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>.&nbsp; See also below <b>Choice
+ 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). Don't use the -E options on dispcal and 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>
+ &nbsp;&nbsp;&nbsp; EBU 3213 or "PAL 576i" primaries.<br>
+ <br>
+ &nbsp;&nbsp;&nbsp; SMPTE RP 145 or "NTSC 480i" primaries.<br>
+ <br>
+ For High Definition:<br>
+ <br>
+ &nbsp;&nbsp;&nbsp; Rec 709 primaries.<br>
+ <br>
+ For Ultra High Defintion<br>
+ <br>
+ &nbsp;&nbsp;&nbsp; Rec 2020 primaries.<br>
+ <br>
+ For Digital Cinema<br>
+ <br>
+ &nbsp;&nbsp;&nbsp; SMPTE-431-2&nbsp; 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:&nbsp;&nbsp;&nbsp; <br>
+ <br>
+ &nbsp;&nbsp;&nbsp; EBU3213_PAL.icm<br>
+ <br>
+ &nbsp;&nbsp;&nbsp; SMPTE_RP145_NTSC.icm<br>
+ <br>
+ &nbsp;&nbsp;&nbsp; Rec709.icm<br>
+ <br>
+ &nbsp;&nbsp;&nbsp; Rec2020.icm<br>
+ <br>
+ &nbsp;&nbsp;&nbsp; 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 &amp;
+ 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 &amp; 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) BT.1886 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 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 a black point offset. So
+ another means of making the viewing adjustment is to apply the
+ BT.1886-like response to 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&nbsp; 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> 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 rendered to a model BT.1886 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. </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>
+ &nbsp; <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>
+ &nbsp; <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>
+ &nbsp; <tt>targen -v -d3 -s30 -g100 -f1000 -cTVmtx.icm -V1.8 TV</tt><br>
+ <br>
+ The display can then be measured:<br>
+ <br>
+ &nbsp; <tt>dispread -v -k TV.cal TV</tt><br>
+ <br>
+ or using madTPG:<br>
+ <br>
+ &nbsp;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>
+ &nbsp; <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>
+ &nbsp; <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>&nbsp; collink -v -Ib:2.4 -G -ir Rec709.icm TV.icm
+ HD.icm&nbsp;&nbsp; # dark conditions</tt><tt><br>
+ </tt><tt> &nbsp; collink -v -Ib&nbsp;&nbsp;&nbsp;&nbsp; -G -ir
+ Rec709.icm TV.icm HD.icm&nbsp;&nbsp; # dim conditions - good
+ default</tt><tt><br>
+ </tt><tt> &nbsp; collink -v -Ib:2.1 -G -ir Rec709.icm TV.icm
+ HD.icm&nbsp;&nbsp; # mid to dim conditions</tt><tt><br>
+ </tt><tt> &nbsp; collink -v -Ib:2.0 -G -ir Rec709.icm TV.icm
+ HD.icm&nbsp;&nbsp; # mid to light conditions</tt><br>
+ <br>
+ or you could do it using pure CIECAM02 adjustment and a black point
+ mapping:<br>
+ <br>
+ <tt>&nbsp; collink -v -ctv -dmd -da:1 -G -ila Rec709.icm TV.icm
+ HD.icm&nbsp; # very dark conditions</tt><tt><br>
+ </tt><tt> &nbsp; collink -v -ctv -dmd -da:3 -G -ila Rec709.icm
+ TV.icm HD.icm&nbsp; # dim conditions</tt><tt><br>
+ </tt><tt> &nbsp; collink -v -ctv -dmd -da:7 -G -ila Rec709.icm
+ TV.icm HD.icm&nbsp; # mid to dim conditions - good default</tt><tt><br>
+ </tt><tt> &nbsp; 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> &nbsp; collink -v -Ib -c md -dmd -da:5&nbsp; -G -ila
+ Rec709.icm TV.icm HD.icm # very dark conditions</tt><tt><br>
+ </tt><tt> &nbsp; collink -v -Ib -c md -dmd -da:10 -G -ila Rec709.icm
+ TV.icm HD.icm&nbsp; # dim conditions</tt><tt><br>
+ </tt><tt> &nbsp; collink -v -Ib -c md -dmd -da:18 -G -ila Rec709.icm
+ TV.icm HD.icm&nbsp; # mid to dark conditions</tt><tt><br>
+ </tt><tt> &nbsp; collink -v -Ib -c md -dmd -da:30 -G -ila Rec709.icm
+ TV.icm HD.icm&nbsp;&nbsp; # 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>
+ &nbsp;&nbsp;&nbsp; <tt>dispwin TV.cal</tt><br>
+ <br>
+ or the simple matrix profile installed:<br>
+ <br>
+ &nbsp;&nbsp;&nbsp; <tt>dispwin -I TVmtx.icm</tt><br>
+ <br>
+ or a the more complete display profile could be installed:<br>
+ <br>
+ &nbsp; 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>
+ &nbsp; <tt>collink -v -3e -Ib -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">&lt;http://www.avsforum.com/t/1464890/eecolor-processor-argyllcms&gt;</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>
+ &nbsp; <tt>collink -v -3e -et -Et -Ib -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.&nbsp; 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>&nbsp;&nbsp;&nbsp; collink -v -3m -et -Et -Ib -G -ir -H TV.cal
+ Rec709.icm TV.icm HD.icm</tt><tt><br>
+ </tt><tt> </tt><tt><br>
+ </tt><tt> &nbsp;&nbsp;&nbsp; collink -v -3m -et -Et -Ib -G -ir </tt><tt><tt>-H
+
+
+
+
+
+
+
+
+
+
+
+ TV.cal </tt>EBU3213_PAL.icm TV.icm SD_PAL.icm</tt><tt><br>
+ </tt><tt> </tt><tt><br>
+ </tt><tt> &nbsp;&nbsp;&nbsp; collink -v -3m -et -Et -Ib -G -ir </tt><tt><tt>-H
+
+
+
+
+
+
+
+
+
+
+
+ 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>&nbsp;&nbsp;&nbsp; collink -v -3m -et -Et -Ib -G -ir -a TV.cal
+ Rec709.icm TV.icm HD.icm</tt><tt><br>
+ </tt><tt> </tt><tt><br>
+ </tt><tt> &nbsp;&nbsp;&nbsp; collink -v -3m -et -Et -Ib -G -ir </tt><tt><tt>-a
+
+
+
+
+
+
+
+
+
+
+
+ TV.cal </tt>EBU3213_PAL.icm TV.icm SD_PAL.icm</tt><tt><br>
+ </tt><tt> </tt><tt><br>
+ </tt><tt> &nbsp;&nbsp;&nbsp; collink -v -3m -et -Et -Ib -G -ir </tt><tt><tt>-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>&nbsp; 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 a
+ VRML 3d visualization of the point set using the -W flag. It is
+ good to take a look at the verifyd.wrl file using a VRML viewer.
+ 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>&nbsp; copy verify.ti1 ref.ti1<br>
+ &nbsp; fakeread -v -b 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:2.15" then the equivalent fakeread option
+ "-b 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 &amp; calibration will be, by
+ simulating the reproduction of this test set:<br>
+ </p>
+ <p><tt>&nbsp; copy verify.ti1 checkA.ti1</tt><tt><br>
+ &nbsp; fakeread -v -et -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>&nbsp; fakeread -v -et -p HD.icm -Et -K TV.cal TV.icm checkA</tt></p>
+ <p><tt>and then you can verify:<br>
+ </tt></p>
+ <p><tt>&nbsp; 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>&nbsp; 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 a VRML plot of the errors in L*a*b* space. The important
+ thing is to take a look at the checkA.wrl 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>&nbsp; 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>&nbsp; iccgamut -ff -ia Rec709</tt><tt><br>
+ </tt><tt> &nbsp; iccgamut -ff -ia TV.icm</tt><tt><br>
+ </tt><tt> &nbsp; viewgam -i Rec709.gam TV.gam gamuts.wrl</tt><br>
+ </p>
+ <p>and look at the gamuts.wrl file, as well as taking notice of % of
+ the video volume that the display intersects. The VRML 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 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>&nbsp; copy verify.ti1 checkB.ti1</tt><tt><br>
+ </tt><tt> &nbsp; dispread -v 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>&nbsp; dispread -v -d madvr -V checkB</tt><br>
+ </p>
+ <p>Verify the same way as above:<br>
+ </p>
+ <p><tt>&nbsp; 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>&nbsp; v</tt><tt>erify -v -n -w -x -L TV.icm ref.ti3
+ checkB.ti3</tt></p>
+ <p><br>
+ </p>
+ <p>&nbsp;<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>