From 22f703cab05b7cd368f4de9e03991b7664dc5022 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=B6rg=20Frings-F=C3=BCrst?= Date: Mon, 1 Sep 2014 13:56:46 +0200 Subject: Initial import of argyll version 1.5.1-8 --- doc/dispcal.html | 2256 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 2256 insertions(+) create mode 100644 doc/dispcal.html (limited to 'doc/dispcal.html') diff --git a/doc/dispcal.html b/doc/dispcal.html new file mode 100644 index 0000000..7327c8f --- /dev/null +++ b/doc/dispcal.html @@ -0,0 +1,2256 @@ + + + + dispcal + + + + +

spectro/dispcal

+

Summary

+ Given calibration target information [white point, maximum + brightness, and response curve ("gamma")], display a series of test + patches on the display, and using the colorimetric values read, + create a calibration lookup tables that make the display meet the + desired target. The type of instrument is determined by the + communication port selected. Emission and display measurement + instruments are supported.
+

Usage

+ dispcal + [-options] inoutfile
+  -v [n] +               + + + + + + + + + + + + + + + + + + + + Verbose mode
+  -display displayname [X11 only] Choose X11 display + name
+  -d n[,m] +             + [X11 only]Choose the display from the following list (default + 1),
+                       +and +optionally +choose +a +different +display +m +for + + + + + + + + + + + + + + + + + + + + VideoLUT access.
+  -d n                 +Choose +the +display +from +the +following +list +(default + + + + + + + + + + + + + + + + + + + + 1)
+  -dweb[:port]         + + + + + + + + + + + + + + + + + + + Display via a web server at port (default 8080)
+   -c + + + + + + + + + + + + + + + + + + + + listno     +        Set communication port from + the following list (default 1)
+  -r +              +      Report on the calibrated display then + exit
+  -R +              +      Report on the uncalibrated display then + exit
+  -m +              +      Skip adjustment of the monitor + controls
+   -o [profile.icm]     Create + fast matrix/shaper profile [different filename to outfile.icm]
+  -O description       + + + + + + + + + + + + + + + + + + + + Fast ICC Profile Description string (Default "outfile")
+  -u                   +Update +previous +calibration +and +(if +-o +used) +ICC + + + + + + + + + + + + + + + + + + + + profile VideoLUTs
+  -q [lmh]             + + + + + + + + + + + + + + + + + + + + Quality - Low, Medium (def), High
+  -p                   + + + + + + + + + Use telephoto mode (ie. for a projector) (if available)
+  -y X +                 + + + + + + + + + + + + + + + + + + + + Display type - instrument specific list to choose from.
+  -t [temp]            +White +Daylight +locus +target, +optional +target +temperaturee +in + + + + + + + + + + + + + + + + + + + + deg. K (deflt.)
+  -T [temp]            +White +Black +Body +locus +target, +optional +target +temperaturee + + + + + + + + + + + + + + + + + + + + in deg. K
+  -w x,y               + + + + + + + + + + + + + + + + + + + + Set the target white point as chromaticity coordinates
+  -b bright            + + + + + + + + + + + + + + + + + + + + Set the target white brightness in cd/m^2
+  -g gamma             + + + + + + + + + + + + + + + + + + + + Set the target response curve gamma (Def. 2.4)
+                       + + + + + + + + + + + + + + + + + + + + Use "-gl" for L*a*b* curve
+                + + + + + + + + + + + + + + + + + + + +        Use "-gs" for sRGB curve
+                       +Use +"-g709" +for +REC +709 +curve +(should +use + + + + + + + + + + + + + + + + + + + + -a as well!)
+                       + + + + + + + + + + + + + + + + + + + + Use "-g240" for SMPTE 240M curve (should use -a as well!)
+                       + + + + + + + + + + + + + + + + + + + + Use "-G2.4 -f0" for BT.1886                                           + + + + + + + + + + + + +
+  -G gamma +             + Set the target response curve actual technical gamma
+  -f [degree]          +Amount +of +black +level +accounted +for +with +output + + + + + + + + + + + + + + + + + + + + offset (default all output offset)
+  -a ambient           + + + + + + + + + + + + + + + + + + + + Use viewing condition adjustment for ambient in Lux
+  -k factor +            + Amount to try and correct black point hue. Default 1.0, LCD + default 0.0
+  -A rate +              + Rate of blending from neutral to black point. Default 4.0
+  -B bkbright          + + + + + + + + + + + + + + + + + + + + Set the target black brightness in cd/m^2
+  -e [n]               + + + + + + + + + + + + + + + + + + + + Run n verify passes on final curves
+  -E +                   + + + + + + + + + + + + + + + + + + + + Run only verify pass on installed calibration curves
+  -P + ho,vo,ss[,vs]     Position test window + and scale it
+                       +ho,vi: +0.0 += +left/top, +0.5 += +center, +1.0 + + + + + + + + + + + + + + + + + + + + = right/bottom etc.
+                       +ss: +0.5 += +half, +1.0 += +normal, +2.0 + + + + + + + + + + + + + + + + + + + + = double etc.
+                       + + + + + + + ss,vs: = optional horizontal, vertical scale.
+  -F +                   + + + + + + + + + + + + + + + + + + + + Fill whole screen with black background
+  -n              +     +[X11 +only] +Don't +set +override +redirect +on + + + + + + + + + + + + + + + + + + + + test window
+  -J +              +      Run instrument calibration first
+  -N                   + + + + + + + + + + + + + + + + + + + + Disable initial calibration of instrument if possible
+  -H +              +      Use high resolution spectrum mode (if + available)
+
+  -X file.ccmx         + + + + + + + + + + + + + + + + + + + + Apply Colorimeter Correction Matrix
+  -X + file.ccss          +Use +Colorimeter +Calibration + + + + + + + + + + + + + + + + + + + + Spectral Samples for calibration
+  -Q observ        +     Choose CIE Observer for spectrometer or CCSS + colorimeter data:
+             + + + + + + + + + + + + + + + + + + + +           1931_2 (def.), 1964_10, S&B 1955_2, shaw, + J&V 1978_2, 1964_10c
+  -I b|w               + + + + + + + + + + + + + + + + + + + + Drift compensation, Black: -Ib, White: -Iw, Both: -Ibw
+  -Y A +             +     Use non-adaptive integration time mode (if + available).
+  -C "command" +         Invoke shell + "command" each time a color is set
+  -M "command" +         Invoke shell + "command" each time a color is measured
+  -W n|h|x             +Override +serial +port +flow +control: +n += +none, + + + + + + + + + + + + + + + + + + + + h = HW, x = Xon/Xoff
+  -D [level]           + + + + + + + + + + + + + + + + + + + + Print debug diagnostics to stderr
+  inoutfile            + + + + + + + + + + + + + + + + + + + + Base name for created + or updated .cal  and .icm output files
+
+

Comments
+

+ This is the tool is used for adjusting and calibrating a display to + reach specified target behaviour, and optionally profiling it.  + For best results on a CRT, you should run this against a neutral + grey desktop background, and avoid having any bright images or + windows on the screen at the time you run dispcal. You could also + use the -B option to black + the whole screen out, although this will make it impossible to + control dispcal unless you have more than one display.
+
+ The -v flag reports progress information, + as well as other statistics about the progress of calibration. A + numerical argument greater than 1 gives greater verbosity.
+
+ When running on a UNIX based system that used + the X11 Windowing System, dispcal will by default use the + $DISPLAY environment variable to determine which local or remote + display and screen to read from. This can be overridden by supplying + an X11 display name to the -display + option. Note that if Xinerama is active, you can't select the screen + using $DISPLAY or -display, you have to select it using the -d parameter.
+
+ By default the main display will be the location of + the test window. If the system has more than one display or screen, + an alternate display/screen can be selected with the -d parameter. If you invoke dispcal so as to display the + usage information (i.e. "dispcal -?" or "dispcal --"), then the + discovered displays/screens will be listed. Multiple displays may + not be listed, if they appear as a single display to the operating + system (ie. the multi-display support is hidden in the video card + driver). On UNIX based system that used the X11 Windowing System, + the -d parameter will + override the screen specified by the $DISPLAY or parameter.
+
+ Note that if VideoLUTs for a + display are not accessible (i.e. no hardware calibration + capability), dispcal will + will issue a warning, but continue creating a calibration based on + the display "as-is" rather than its native response. See the -o flag for an explanation of the + implications of having no access to the VideoLUTs.
+
+ On X11 the inability to access VideoLUTs could be because you are + trying to access a remote display, and the remote display doesn't + support the XF86VidMode extension, or perhaps you are running + multiple monitors using NVidia TwinView, or MergedFB, and trying to + access anything other than the primary monitor. TwinView and + MergedFB don't properly support the XF86VidMode extension for + multiple displays. You can use dispwin -r + to test whether the VideoLUTs are accessible for a particular + display. See also below, on how to select a different display for + VideoLUT access. Also note that dispcal will fail if the Visual + depth doesn't match the VideoLUT depth. Typically the VideoLUTs have + 256 entries per color component, so the Visual generally needs to be + 24 bits, 8 bits per color component.
+
+ Because of the difficulty cause by TwinView and + MergedFB in X11 based systems, you can optionally specify a separate + display number after the display that is going to be used to present + test patches, for accessing the VideoLUT hardware. This must be + specified as a single string, e.g. -d + + + + + + + + + + + + + + + + + + + + 1,2 . Some experimentation may be needed using dispwin on such systems, to discover what + screen has access to the VideoLUT hardware, and which screens the + test patches appear on. You may be able to calibrate one screen, and + then share the calibration with another screen. Profiling can be + done independently to calibration on each screen.
+
+ -dweb or + -dweb:port starts a + standalone web server on your machine, which then allows a local or + remote web browser to display the the color test patches. By default + port 8080 is used, but this + can be overridden by appending a : + and the port number i.e. -dweb:8001. + The URL will be http:// + then name of the machine or its I.P. address followed by a colon and + the port number - e.g something like http://192.168.0.1:8080. If you use the verbose + option (-v) then a likely + URL will be printed once the server is started, or you could run ipconfig (MSWin) or /sbin/ifconfig (Linux or OS X) + and identify an internet address for your machine that way. JavaScript + needs to be enabled in your web browser for this to work.
+
+ Note that if you use this method of displaying test patches, that + there is no access to the display VideoLUTs and that the colors will + be displayed with 8 bit per component precision, and any + screen-saver or power-saver will not be disabled. You will also be + at the mercy of any color management applied by the web browser, and + may have to carefully review and configure such color management. + See the -o flag for an explanation of the + implications of having no access to the VideoLUTs.
+
+ -c The + instrument is assumed to communicate through a USB or serial + communication port, and the port can be selected with the -c + option, if the instrument is not connected to the first port. If you + invoke dispcal so as to + display the usage information (i.e. "dispcal -?" or "dispcal --"), + then the discovered USB and serial ports will be listed. On + UNIX/Linux, a list of all possible serial ports are shown, but not + all of them may actually be present on your system.
+
+ The -r and + -R flags + perform a quick measurement of current display behaviour, reports + and then exits. If the -r + flag is used the measurement are taken using the currently loaded + calibration (Video LUT) curves. If -R + is use, then the uncalibrated ("raw" or "native") behaviour is + measured. Reported are:
+
+     Black Brightness in cd/m^2
+     White Brightness in cd/m^2
+     The approximate Gamma
+     The white point x,y chromaticity co-ordinates
+     The correlated color temperature in Kelvin, and + the CIEDE200 to the Black Body locus.
+     The correlated Daylight temperature in Kelvin, + and the CIEDE200 to the Daylight locus.
+     The visual color temperature in Kelvin, and the + CIEDE200 to the Black Body locus.
+     The visual Daylight temperature in Kelvin, and + the CIEDE200 to the Daylight locus.
+     The visual color temperature in Kelvin
+ (for -R "raw":)
+     The apparent VideoLUT entry number of significant + bits.
+
+ Note that the correlated color temperature is the temperature of a + black body radiator that has the closest color to the white point + measured using the traditional CIE 1960 UCS space color difference + formula. The correlated daylight temperature is a similar thing, + except the CIE daylight locus is used. The visual color temperature + values are calculated similarly to the correlated color + temperatures, but using the modern CIEDE2000 color difference + formula to calculate a better visual approximation to the closest + temperature to the displays white point. There will be no difference + between the UCS and CIEDE2000 temperatures if the display white + point actually lies on the particular locus.
+
+ The -m + option skips the usual process of adjusting the display monitor + contrast, brightness and white point controls, and skips straight to + calibration.
+
+ -o [profile.icm] Normally dispcal creates just a + calibration file, which can then be used for subsequent + characterization using dispread and + profiling using colprof. If the -o flag is used, dispcal will also create a + shaper/matrix profile. By default it will create a profile named inoutfile.icm, but a differently + named file can be created or updated by specifying the name after + the -o flag. If the -u flag is used with -o, then the ICC profile vcgt calibration curves will be + updated.
+
+ Note that if VideoLUT access is not possible for the display, that + hardware calibration is not possible. dispcal will create + calibration curves anyway with a warning, and if a profile is + created, it will not 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 + R=G=B=1.0. Some systems may not cope properly with this type of + profile. See the tutorial for a + further explanation.
+
+ The -O parameter allows setting of the + shaper/matrix profile description tag. The parameter should be a + string that describes the device and profile. With most command line + shells, it will be necessary to enclose the parameter with double + quotes, so that spaces and other special characters are included in + the parameter, and not mistaken for the start of another flag, or as + a final command line parameter. Many programs that deal with ICC + profiles use the description tag to identify a profile, rather than + the profile filename, so using a descriptive string is important in + being able to find a profile. By default, the profile file name will + be used as the description.
+
+ -u Normally + dispcal creates a new + calibration file and optional profile, based on the requested + targets and the response of the display. This can take a fair amount + of time, particularly if a high quality level has been selected, so + to speed up the process of keeping a display in calibration the -u flag can be used. This uses + the same calibration targets as the previous calibration but does a + smaller number of refinement passes, enough to improve the accuracy + of the calibration to account for drift in the device. If the -o flag is used as well, then + the ICC profile will have + its vcgt tag updated with the new calibration. This keeps the + profile up to date with the display. Normally dispcal -u will use the same + quality level that was specified in the previous calibration, but + this can be overridden using the -q + flag. Any options that attempt to change the calibration target (ie. + white point, brightness, gamma etc.) will be ignored. Adjustment of + the display monitor controls is skipped. A profile cannot be updated + if the display does not support hardware calibration (no VideoLUT + access).
+
+   Quality - Low, Medium (def), High. The -q flag determines how much time + and effort to go to in calibrating the display. The higher the + quality, the more test readings will be done, the more refinement + passes will be done, the tighter will be the accuracy tolerance, and + the more detailed will be the calibration of the display. The result + will ultimately be limited by the accuracy of the instrument, the + repeatability of the display and instrument, and the resolution of + the Video Lookup table entries and Digital or Analogue output + (RAMDAC).
+
+ The -p flag + allows measuring in telephoto mode, using instruments that support + this mode, e.g. the ColorMunki. Telephoto mode is one for taking + emissive measurements from a distance (ie. telespectometer, + tele-colorimeter) mode, and typically would be used for measuring + projector type displays. If a device does not support a specific + telephoto mode, then the normal emissive mode may be suitable for + measuring projectors.
+
+   The -y + flag allows setting the Display Type. The selection typically + determines two aspects of of the instrument operation: 1) It may set the measuring mode + to suite refresh or non-refresh displays. + Typically only LCD (Liquid Crystal) displays have a non-refresh + nature. 2) It may select an + instrument calibration matrix suitable for a particular display + type. The selections available depends on the type and model of + instrument, and a list of the options for the discovered instruments + will be shown in the usage + information. For more details on what particular instruments support + and how this works, see Operation of + particular instruments. 3) Any installed CCSS files + (if applicable), or CCMX files. These files are typically created + using ccxxmake, + and installed using oeminst. The + default and Base Calibration types will be indicated in the usage.
+
+ -t Set the target white point + locus to the equivalent of a Daylight spectrum of the given + temperature in degrees Kelvin. By default the white point target + will be the native white of the display, and it's color temperature + and delta E to the daylight spectrum locus will be shown during + monitor adjustment, and adjustments will be recommended to put the + display white point directly on the Daylight locus. If a Daylight + color temperature is given as an argument to -t, then this will become the + target of the adjustment, and the recommended adjustments will be + those needed to make the monitor white point meet the target. + Typical  values might be 5000 for matching printed output, or + 6500, which gives a brighter, bluer look. A white point temperature + different to that native to the display may limit the maximum + brightness possible.
+
+ -T  Same functionality as + the -t option, except the + white point locus will be the Black Body, or Planckian locus, rather + than the Daylight locus. While these two white point loci are quite + close, they are subtly different. If a temperature is given as an + argument, this will become the Black Body target temperature during + adjustment.
+
+ -w  An + alternative to specifying a  white point target in Daylight or + Black Body degrees Kevin, is to specify it in chromaticity + co-ordinates. This allows the white point to be a color other than + one on the Daylight or Black Body. Note that the x,y numbers must be + specified as a single string (no space between the numbers and the + comma).
+
+ -b  Set + the target brightness of white in cd/m^2. If this number cannot be + reached, the brightest output possible is chosen, consistent with + matching the white point target. Note that many of the instruments + are not particularly accurate when assessing the absolute display + brightness in cd/m^2. NOTE + that some LCD screens behave a little strangely near their absolute + white point, and may therefore exhibit odd behavior at values just + below white. It may be advisable in such cases to set a brightness + slightly less than the maximum such a display is capable of.
+
+ -g gamma  +Set + + + + + + + + + + + + + + + + + + + + the target response curve gamma. This is normally an exponential + curve (output = input ^gamma), and defaults to 2.4 on MSWindows and + Macintosh OS X 10.6 or latter and Linux/Unix (which is typical of a + CRT type displays real response), and 1.8 on a Macintosh (prior to + OS X 10.6). Four pre-defined curves can be used as well: the sRGB + colorspace response curve, which is an exponent curve with a + straight segment at the dark end and an overall response of + approximately gamma 2.2 (-gs), +the + + + + + + + + + + + + + + + + + + + + L* curve, which is the response of the CIE L*a*b* perceptual + colorspace (-gl). the REC + 709 video standard response curve (-g709) + and the SMPTE 240M video standard response curve (-g240)
+
+ Note that a real display + can't reproduce any of these ideal curves, since it will have a + non-zero black point, whereas all the ideal curves assume zero light + at zero input. In the case of a gamma curve target, dispcal uses an + actual technical power curve shape that aims for the same relative + output at 50% input as the ideal gamma power curve. To allow for the + non-zero black level of a real display, by default dispcal will offset the target + curve values so that zero input gives the actual black level of the + display (output offset). This ensures that the target curve better + corresponds to the typical natural behavior of displays, but it may + not be the most visually even progression from display minimum, but + this behavior can be changed using the -f option (see below).
+
+ Also note that many color + spaces are encoded with, and labelled as having a gamma of + approximately 2.2 (ie. sRGB, + REC 709, SMPTE 240M, Macintosh OS X 10.6), but are actually intended + to be displayed on a display with a typical CRT gamma of 2.4 viewed in a darkened + environment. This is because this 2.2 + gamma is a source gamma encoding in bright viewing conditions such + as a television studio, while typical display viewing conditions are + quite dark by comparison, and a contrast expansion of (approx.) + gamma 1.1 is desirable to make the images look as intended. So if + you are displaying images encoded to the sRGB standard, or + displaying video through the calibration, just setting the gamma + curve to sRGB or REC 709 (respectively) is probably not what you want! What you + probably want to do, is to set the gamma curve to about gamma 2.4, + so that the contrast range is expanded appropriately, or alternatively + use sRGB or REC 709 or a gamm of 2.2 but also use the -a + parameter to specify the actual ambient viewing conditions, so that + dispcal can make an + appropriate contrast enhancement. If your instrument is capable of + measuring ambient light levels, then you can do so during the + interactive display control adjustment. See + <http://www.color.org/sRGB.xalter> for details of how sRGB is + intended to be used.
+
+ It is hard to know whether Apple Macintosh computers prior to OS X + 10.6 should also have such an adjustment, since it is not really + possible to know whether colors labelled as being in such a + colorspace are actually encoded in that gamma with the expectation + that they will be displayed on a display with that actual response, + or whether they are intended to be displayed on a display that + contrast expands by a power 1.1.  Both situations might be the + case, depending on how source material is created!
+
+ -G gamma  +As + + + + + + + + + + + + + + + + + + + + explained above, the gamma value provided to the -g option is used to set and + actual response curve that makes an allowance for the non-zero black + of the actual display, and will have the same relative output at 50% + input as the ideal gamma power curve, and so best matches typical + expectations. The -G option + is an alternative that allows the actual + power to be specified instead, meaning that when combined with the + displays non-zero black value, the response at 50% input will + probably not match that of the ideal power curve with that gamma + value.
+
+ -f [degree]: + As explained in for the -g + and -G options, real + displays do not have a zero black response, while all the target + response curves do, so this has to be allowed for in some way. The + default way of handling this (equivalent to -f 1.0)  is to + allow for this at the output of the ideal response curve, by + offsetting and scaling the output values. This defined a curve that will match the responses + that many other systems provide and may be a better match to the + natural response of the display, but will give a less visually even + response from black. The + other alternative is to offset and scale the input values into the + ideal response curve so that zero input gives the actual non-zero + display response. This ensures the most visually even progression + from display minimum, but might be hard to achieve since it is + different to the naturally response of a display. A subtlety is to + provide a split between how much of the offset is accounted for as + input to the ideal response curve, and how much is accounted for at + the output, and this can be done by providing a parameter -f degree, where the degree is + 0.0 accounts for it all as input offset, and 1.0 accounts for all of + it as output offset. If -f + is used without a specified degree, a degree of 0.0 is assumed, the + opposite of the default. Note + that using all input offset (degree == 0.0) is equivalent to the use + of the BT.1886 transfer + function.
+
+ -a ambient: + As explained for the -g + parameter, often colors are encoded in a situation with viewing + conditions that are quite different to the viewing conditions of a + typical display, with the expectation that this difference in + viewing conditions will be allowed for in the way the display is + calibrated. The -a option + is a way of doing this. By default dispcal + will not make any allowances for viewing conditions, but will + calibrate to the specified response curve, but if the -a option is used, or the + ambient level is measured during the interactive display controls + portion of the calibration, an appropriate viewing conditions + adjustment will be performed. For a gamma value or sRGB, the + original viewing conditions will be assumed to be that of the sRGB + standard viewing conditions, while for REC 709 and SMPTE 240M they + will be assumed to be television studio viewing conditions. By + specifying or measuring the ambient lighting for your display, a + viewing conditions adjustment based on the CIECAM02 color appearance + model will be made for the brightness of  your display and the + contrast it makes with your ambient light levels.
+
+ -k factor: + Normally this will be set automatically, based on the measured black + level of the display. A -k + factor of 1.0 will make all colors down the neutral axis (R=G=B) + have the same hue as the chosen white point. Near the black point, + red, green or blue can only be added, not subtracted from zero, so + the process of making the near black colors have the desired hue, + will lighten them to some + extent. For a device with a good contrast ratio or a black point + that has nearly the same hue as the white, this should not affect + the contrast ration too severely. If the device contrast ratio is + not so good, and the native black hue is noticeably different to + that of the chosen white point (which is often the case for LCD type displays, or CRT type displays with one + channel which has a poor level of black), this could have a + noticeably detrimental effect on an already limited contrast ratio, + and result in a black that is not as good as it can be, and a lower + -k factor should be used. -k values can range between 0.0 + (no correction of black) to 1.0 (full correction of black). If less + than full correction is chosen, then the resulting calibration + curves will have the target white point down most of the curve, but + will then blend over to the native or compromise black point that is + blacker, but not of the right hue. The rate of this blend can be + controlled with the -A + parameter (see below).
+
+ -A rate:  +If + + + + + + + + + + + + + + + + + + + + the black point is not being set completely to the same hue as the + white point (ie. because the -k + factor is less than 1.0), then the resulting calibration curves will + have the target white point down most of the curve, but will then + blend over to the native or compromise black point that is blacker, + but not of the right hue. The rate of this blend can be controlled + with the -A parameter. The + default value 4.0, which results in a target that switches from the + white point target to the black, moderately close to the black + point. While this typically gives a good visual result with the + target neutral hue being maintained to the point where the crossover + to the black hue is not visible, it may be asking too much of some + displays (typically LCD type displays), and there may be some visual + effects due to inconsistent color with viewing angle. For this + situation a smaller value may give a better visual result (e.g. try + values of 3.0 or 2.0. A value of 1.0 will set a pure linear blend + from white point to black point). If there is too much coloration + near black, try a larger value, e.g. 6.0 or 8.0.
+
+ -B  Set + the target brightness of black in cd/m^2. Setting too high a value + may give strange results as it interacts with trying to achieve the + target "advertised" gamma curve shape. You could try using -f 1 if + this causes a problem.
+
+ -e [n] Run n verify passes on the final + curves. This is an extra set of instrument readings, that can be + used to estimate how well the device will match the targets with the + computed calibration curves. Note that the usefulness of the + verification is sometimes limited by the repeatability of the device + & instrument readings. This is often evident for CRT displays, + which (due to their refresh rate) flicker. More than one + verification pass can be done by providing the parameter n, and by then comparing the + successive verifications, some idea of the repeatability can be + ascertained. The verification uses a fixed number of semi-random + test values to test the calibration.
+
+ -E Run + verify pass on the display as it is currently setup (currently + installed LUT curves). This will use the usual input parameters to + establish the expected (target) characteristic. Note that if the initial + calibration was modified due to it being out of gamut of the + display, verify will show the resulting discrepancy. You can use dispwin to load a .cal file into the display + before running dispcal -E. + Note that if you set an Ambient light level interactively during the + calibration, you need to enter the same number that was measured and + set using the -a parameter + for verify.
+
+ The -P + parameter allows you to position and size the test patch window. By + default it is places in the center of the screen, and sized + appropriately for the type of instrument. The ho and vo values govern the horizontal + and vertical offset respectively. A value of 0.0 positions the + window to the far left or top of the screen, a value of 0.5 + positions it in the center of the screen (the default), and 1.0 + positions it to the far right or bottom of the screen. If three + parameters are provided, then the ss + parameter is a scale factor for the test window size. A value of 0.5 + for instance, would produce a half sized window. A value of 2.0 will + produce a double size window. If four parameters are provided, then + the last two set independent horizontal and vertical scaling + factors. Note that the ho,vo,ss or ho,vo,hs,vs numbers must be + specified as a single string (no space between the numbers and the + comma). For example, to create a double sized test window at the top + right of the screen, use -P 1,0,2 + . To create a window twice as wide as high: -P 1,0,2,1.
+
+ The -F + flag causes the while screen behind the test window to be masked + with black. This can aid black accuracy when measuring CRT displays + or projectors.
+
+ -n When + running on a UNIX based system that used the X11 Windowing System, dispcal + normally selects the override redirect so that the test window will + appear above any other windows on the display. On some systems this + can interfere with window manager operation, and the -n + option turns this behaviour off.
+
+ The -J + option runs through the black and sensor relative calibration + routines for the Xrite DTP92 and DTP94 instruments, the black level + calibration for the Eye-One Display 1, and a CRT frequency + calibration for the Eye-One Display 2. For the black calibration the + instrument should be placed on an opaque, black surface, and any + stray light should be avoided by placing something opaque over the + instrument. If a Spectrolino is being used, then a white and black + calibration will always be performed before the instrument can be + placed on the display, unless the -N + flag is used. Generally it is not necessary to do a calibration + every time an instrument is used, just now and again. There is also + no point in doing  a CRT frequency calibration, as this will be + done automatically at the commencement of patch reading, and will be + lost between runs.
+
+ -N Any + instrument that requires regular calibration will ask for + calibration on initial start-up. Sometimes this can be awkward if + the instrument is being mounted in some sort of measuring jig, or + annoying if several sets of readings are being taken in quick + succession. The -N + suppresses this initial calibration if a valid and not timed out + previous calibration is recorded in the instrument or on the host + computer. It is advisable to only use this option on the second and + subsequent measurements in a single session.
+
+ The -H + option turns on high resolution spectral mode, if the instrument + supports it, such as the Eye-One Pro. See Operation of particular instruments + for more details. This may give better accuracy for display + measurements.
+
+ The -X file.ccmx option reads + a Colorimeter Correction Matrix + from the given file, and applies it to the colorimeter instruments + readings. This can improve a colorimeters accuracy for a particular + type of display. A list of contributed ccmx files is here.
+
+ The -X file.ccss option reads + a Colorimeter Calibration + Spectral Sample from the given file, and uses it to set the + colorimeter instruments calibration. This will only work with + colorimeters that rely on sensor spectral sensitivity calibration + information (ie. the X-Rite i1d3, + or the DataColor Spyder4).This +can +improve +a + + + + + + + + + + + + + + + + + + + + colorimeters accuracy for a particular type of display.
+
+ The -Q flag allows specifying a tristimulus + observer, and is used to compute PCS (Profile Connection Space) + tristimulus values from spectral readings or using a colorimeter + that has CCSS capability. The following choices are available:
+   1931_2 selects the standard CIE 1931 2 degree + observer. The default.
+   1964_10 selects the standard CIE 1964 10 degree + observer.
+   1955_2 selects the Stiles and Birch 1955 2 degree + observer
+   1978_2 selects the Judd and Voss 1978 2 degree + observer
+   shaw selects the Shaw and Fairchild 1997 2 degree + observer
+   1964_10c selects a version of the CIE 1964 10 degree + observer that has been adjusted using a 3x3 matrix to better agree + with the 1931 2 degree observer.
+
+ NOTE that if you select + anything other than the default 1931 2 degree observer, that the Y + values will not be cd/m^2, due to the Y curve not being the CIE 1924 + photopic V(λ) luminosity function.
+
+ The -I b|w options invoke + instrument black level, and display white level compensation + (respectively). Instrument black level drift compensation attempts + to combat instrument black calibration drift by using a display + black test patch as a reference. If an instrument is not + acclimatised sufficiently to the measurement conditions, changes in + temperature can affect the black readings. Display white level drift + compensation attempts to combat changes in display brightness as it + warms up by measuring a white patch every so often, and using it to + normalise all the other readings. If just instrument black drift + compensation is needed, use -Ib. + If just display white level compensation is needed, use -Iw. If both are needed, use -Ibw or -Iwb.
+
+ The -Y A + option uses a non-adaptive integration time emission measurement + mode, if the instrument supports it, such as the Eye-One Pro or + ColorMunki. By default an adaptive integration time measurement mode + will be used for emission measurements, but some instruments support + a fixed integration time mode that can be used with display devices. + This may give increased consistency and faster measurement times, + but may also give less accurate low level readings.
+
+ The -C "command" option allows a + method of relaying each test value to some other display than that + on the system running dispcal (for instance, a photo frame, PDA + screen etc.), by causing the given command to be invoked to the + shell, with six arguments. The first three arguments are the RGB + test color as integers in the range 0 to 255, the second three + parameters are the RGB test color as floating point numbers in the + range 0.0 to 1.0. The script or tool should relay the given color to + the screen in some manner (e.g. by generating a raster file of the + given color and sending it to the display being profiled), before + returning. Note that a test window will also be created on the + system running dispread.
+
+ The -M "command" option allows a + method of gathering each test value from some external source, such + as an instrument that is not directly supported by Argyll. The given + command is involked to the shell, with six arguments. The first + three arguments are the RGB test color as integers in the range 0 to + 255, the second three parameters are the RGB test color as floating + point numbers in the range 0.0 to 1.0. The script or tool should + create a file called "command.meas" + that contains the XYZ values for the given RGB (or measured from the + test window) in cd/m^2 as three numbers separated by spaces, before + returning. If the command returns a non-zero return value, dispcal + will abort. Note that a test window will also be created on the + system running dispcal.
+
+ The -W n|h|x + parameter overrides the default serial communications flow control + setting. The value n turns + all flow control off, h + sets hardware handshaking, and x + sets Xon/Xoff handshaking. This commend may be useful in workaround + serial communications issues with some systems and cables.
+
+ The -D flag causes communications and other + instrument diagnostics to be printed to stdout. A level can be set + between 1 .. 9, that may give progressively more verbose + information, depending on the instrument. This can be useful in + tracking down why an instrument can't connect.
+
+ inoutfile + The final parameter on the command line is the base filename for the + .cal file and the optional ICC + profile. Normally this will be created (or an existing file will be + overwritten). If the -u + flag is used, then these files will be updated. If a different ICC + profile name needs to be specified, do so as an argument to the -o flag.
+
+ NOTE that on an X11 system, + if the environment variable ARGYLL_IGNORE_XRANDR1_2 + is set (ie. set it to "yes"), then the presence of the XRandR 1.2 + extension will be ignored, and other extensions such as Xinerama and + XF86VidMode extension will be used. This may be a way to work around + buggy XRandR 1.2 implementations.
+
+
+

Discussion and guide to display control + adjustment:

+
+ The adjustment of the display controls (brightness, contrast, R, G + & B channel controls etc.) is very dependent on the particular + monitor. Different types and brands of monitors will have different + controls, or controls that operate in different ways. Some displays + have almost no user controls, and so you may well be best skipping + display adjustment, and going straight to calibration.
+
+ Almost all LCD displays lack a real contrast control. Those that do present such a + control generally fake it by adjusting the video signal. For this + reason it is usually best to set an LCD's contrast control at its neutral setting (ie. the + setting at which it doesn't change the video signal). Unfortunately, + it can be hard to know what this neutral setting is. On some + displays it is 50%, others 75%. If the LCD display has a "reset to + factory defaults" mode, then try using this first, as a way of + setting the contrast + control to neutral. The LCD brightness + control generally adjusts the level of backlighting the display + gets, which affects the maximum brightness, and also tends to raise + or lower the black level in proportion, without changing the + displays response curve shape or overall contrast ratio. If your LCD + display has a backlight + control as well as a brightness + control, then the brightness control is also probably being faked, + and you are probably better off setting it to it's neutral setting, + and using the backlight + control in place of brightness + in the following adjustments.
+
+ Some high end displays have the ability to mimic various standard + colorspaces such as sRGB or AdobeRGB. You could choose to calibrate + and profile the display in such an emulation mode, although you + probably don't want to fight the emulations white point and gamma. + To get the best out of such a display you really want to choose it's + "Native Gamut" setting, whatever that is called. Note that some + people have reported bad experiences in trying to use "6-axis custom + controls" on displays such as the Dell U2410, so attempting to use + such a mode should be approached with caution. Ideally such a mode + should be used to give just the underlying native display response, + but the settings to achieve this may be very difficult to determine, + and/or it may not be possible, depending on how such a mode distorts + the RGB signals.
+
+ On CRT based displays, the brightness + control generally adjusts the black level of the display (sometimes + called the offset), and as + a side effect, tends to change the maximum brightness too. A CRT contrast control generally + adjusts the maximum brightness (sometimes called gain) without affecting the + black level a great deal. On a CRT both the brightness and contrast controls will tend to + affect the shape or gamma of the display response curve.
+
+ Many displays have some sort of color temperature adjustment. This + may be in the form of some pre-set color temperatures, or in the + form of individual Red, Green and Blue channel gain adjustments. + Some CRT displays also have R, G & B channel offset adjustments + that will affect the color temperatures near black, as well as + affect the individual channels curve shape. The color temperature + adjustment will generally affect the maximum brightness, and may + also affect the black level and the shape of the display response + curves.
+
+ Some special (expensive) LCD displays may have a white point + adjustment that changes the color of the backlight. If you do not + have one of these types of LCD displays, then attempting to change + the white point of the display (even if it appears to have a "white point selection" or R/G/B "gain" controls") may not be a good idea, as once + again these controls are probably being faked by manipulating the + signal levels. Even if you do manage to change the white point + significantly, it may do things like change the mid tone color too + dramatically, or create a display response that is hard to correct + with calibration, or results in side effects such as quantization + (banding) or other undesirable effects. You may have to try out + various controls (and your aim points for the display calibration), + to decide what is reasonable to attempt on an LCD display.
+
+ Due to the variety of controls as well as the interaction between + them, it can be an iterative process to arrive at a good monitor + set-up, before proceeding on to calibrating and profiling a display. + For this reason, dispcal + offers a menu of adjustment modes, so that the user can + interactively and iteratively adjust the display controls to meet + the desired targets.
+
+   1) Black level (CRT: Brightness)
+   2) White point (Color temperature, R,G,B, Gain/Contrast)
+   3) White level (CRT: Gain/Contrast, LCD: + Brightness/Backlight)
+   4) Black point (R,G,B, Offset/Brightness)
+   5) Check all
+   6) Measure and set ambient for viewing condition adjustment
+   7) Continue on to calibration
+   8) Exit
+
+ There are four basic adjustment modes. Normally one would proceed + through them in the order above, then perhaps repeat the first + adjustment, before checking the overall settings. The White point + and White level modes operate slightly differently, depending on + whether a white target point has been set using the -t -T or -w options, and on whether a + brightness target has been set using the -b option.
+
+
+ The first mode lets you adjust the black level of a CRT display. + Given the current white level, it calculates a value that should + produce a 1% display brightness if the black level is set correctly. + After doing some initial measurements, it will show the target + brightness value (in cd/m^2) on one line, and then underneath it + will show continuously updated readings from the display. The left + most character will switch from '\' to '/' or back again each time a + reading is updated. Some instruments can be quite slow in measuring + dark colors, and it's best to wait for a reading update before + changing the controls more than once. Underneath the target value is + displayed the current reading, and to the right of this is a '+', + '-' or '=' symbol, which gives a hint as to which way to adjust the + brightness control to improve the match to the target.
+
+   Adjust CRT brightness to get target level. + Press space when done.
+      Target + 0.60
+   / Current 0.68  + -
+
+ Once happy with the adjustment, press space to go back to the menu.
+
+
+ The second mode lets you adjust the color of the white point of the + display. If a target white point has been set, it will show the + target brightness value (in cd/m^2) on one line, together with the + target chromaticity co-ordinates for the white point, and then + underneath it will show continuously updated readings from the + display. The left most character will switch from '\' to '/' or back + again each time a reading is updated. Underneath the target + brightness value is displayed the current reading, and then the + current chromaticity co-ordinate values. To the right of this is the + current delta E of the white point from the target, and further to + the right are hints '+', '-' or '='  as to which direction to + adjust the individual Red, Green and Blue gain settings to move the + white point in the direction of the target, and reduce the delta E. + If the symbol is doubled, then this channel will have the greatest + effect. If you do not have individual channel gain controls, then + try choosing amongst color temperature pre-sets, to find one with + the lowest delta E. Depending on the stability of the display, the + coarseness of the controls, and the repeatability of the instrument, + you may not be able to get a perfectly zero delta E.
+
+    Adjust R,G & B gain to get + target x,y. Press space when done.
+      Target B 60.00, x 0.3451, y 0.3516
+   / Current B 60.05, x 0.3426, y 0.3506  DE  + 1.4  R+  G+  B--
+
+ If you did not set a white point target, then the information shown + is a little different - it will show the initial white point value, + as well as the color temperature, and the CIEDE2000 of the white + point to either the Daylight or Black Body locus (depending on + whether the -T flag was + set). The constantly updated values show the same thing, and the + Red, Green and Blue control hints show the direction to adjust the + controls to place the white point on the locus. The control that + will have the most direct effect on the color temperature will be + the Blue, while the Green will most directly move the white point + towards or away from the locus, thereby reducing the delta E of the + white point to the locus (but there is interaction).
+
+ Adjust R,G & B gain to desired white point. + Press space when done.
+   Initial B 47.25, x + 0.3417, y 0.3456, CDT 5113 DE  6.9
+ \ Current B 47.38, x 0.3420, + y 0.3460  CDT 5104 DE  6.7  R-- G+  B-
+
+  The brightness value is just there as a guide to what effect + the adjustment is having on the overall brightness. Usually the + white level brightness is adjusted using the next adjustment mode. + Once happy with the adjustment, press space to go back to the menu.
+
+
+ The third mode lets you adjust the brightness of white on the + display. If you set a target brightness using the -b + parameter, it will show the target brightness value (in cd/m^2) on + one line, and then underneath it will show continuously updated + readings from the display. The left most character will switch from + '\' to '/' or back again each time a reading is updated. Underneath + the target value is displayed the current reading, and to the right + of this is a '+', '-' or '=' symbol, which gives a hint as to which + way to adjust the CRT contrast or LCD brightness control to improve + the match to the target.
+
+    Adjust CRT Contrast or LCD + Brightness to get target level. Press space when done.
+      Target 60.00
+   / Current 59.96  +
+
+ If you did not set a brightness target, it will show the initial + brightness as the target, and the current brightness, which you can + then set any way you want:
+
+ Adjust CRT Contrast or LCD Brightness to desired + level. Press space when done.
+   Initial 47.32
+ / Current 47.54
+
+ Once happy with the adjustment, press space to go back to the menu.
+
+
+ The fourth mode lets you adjust the color of the black point of the + display, if the display has Red, Green and Blue channel offset + controls. It will show the target 1% brightness value (in cd/m^2) on + one line, together with the target chromaticity co-ordinates for the + black point, and then underneath it will show continuously updated + readings from the display. The left most character will switch from + '\' to '/' or back again each time a reading is updated. Underneath + the target brightness value is displayed the current reading, and + then the current chromaticity co-ordinate values. To the right of + this is the current delta E of the black point from the target, and + further to the right are hints '+', '-' or '='  as to which + direction to adjust the individual Red, Green and Blue offset + settings to move the black point in the right direction. If the + symbol is doubled, then this channel will have the greatest effect. +
+
+   Adjust R,G & B offsets to get target x,y. + Press space when done.
+      Target B 0.60, x 0.3451, y 0.3516
+   \ Current B 0.62, x 0.2782, y 0.2331  DE  + 10.3  R+  G++ B-
+
+ The 1%  brightness value is just there as a guide to what + effect the adjustment is having on the 1% brightness level. The + combined channel offsets may have an effect on this in combination + with the CRT brightness control. Press space to go back to the menu.
+
+
+ The fifth selection checks on the overall settings.  If targets + have been set, it will be like:
+
+   Target Brightness = 50.00, Current = 47.44, + error = -5.1%
+   Target 50% Level  = 10.32, Current =  8.10, + error = -4.4%
+   Target Near Black =  0.47, Current =  0.68, + error =  0.4%
+   Target white = x 0.3458, y 0.3586, Current = x 0.3420, y + 0.3454, error =  7.55 DE
+   Target black = x 0.3458, y 0.3586, Current = x 0.2908, y + 0.2270, error = 29.69 DE
+
+ or if no targets are set:
+
+   Current Brightness = 46.28
+   Target 50% + Level  = 10.07, Current =  7.52, error = -5.5%
+   Target Near Black + =  0.46, Current =  0.46, error = -0.0%
+   Current white = x + 0.3439, y 0.3466, VCT 5098K DE  3.0
+   Target black = x + 0.3439, y 0.3466, Current = x 0.3093, y 0.2165, error = 30.30 DE
+
+ and will then go back to the menu.
+
+ The sixth selection 6) + allows the reading of you ambient lighting conditions if your + instrument supports such a mode. Doing so will enable the -a option to compensate for your + viewing conditions in the subsequent calibration. See -a.
+
+ Once  you're happy with the display set-up, you can either + proceed on to the rest of the calibration by selecting 7), or exit and re-start by + selecting 8). You might + want to re-start if you want to change the calibration targets.
+
+
+

Other caveats:

+ NOTE that some LCD screens + behave a little strangely near their absolute white point, and may + therefore exhibit odd behavior at values just below white. It may be + advisable in such cases to set a brightness slightly less than the + maximum such a display is capable of.
+
+ The program attempts to stop any screensaver or powersaver from + interfering with the measurements, but this may not be effective on + some systems, so it may be necessary to manually disable the + screensaver and/or powersaver before commencing the calibration with + a large number of patches.
+
+ The calibration tables produced maintain the maximum level of + precision available on a system. If the display has VideoLUTs + available (Video Lookup Tables that the frame buffer values pass + through on their way to the display) and thier outputs are better + than 8 bits per component, then the resulting curves can reflect + this, although few current operating systems and/or display cards + actually support better than 8 bit per component output.
+
+ If calibration curves are created for a display in which VideoLUTs + are not available, then the resulting calibration file will be + marked to indicate this, and a subsequent profile created with the + calibration will not have the calibration converted to the 'vcgt' + tag, since such a tag can't be loaded into the displays VideoLUTs.
+
+ If communications break down with a USB connected instrument, you + may have to unplug it, and plug it in again to recover operation.
+
+ Some systems (Apple OSX in particular) have a special set of user + interface controls ("Universal Access") that allows altering the + display in ways designed to assist visually impaired users, by + increasing contrast etc. This will interfere badly with any attempts + to calibrate or profile such a system, and must be turned off in + order to do so. Note that certain magic keyboard sequences can turn + this on by accident.
+
+
+
+
+
+ + -- cgit v1.2.3