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/refine.html | 354 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 354 insertions(+) create mode 100644 doc/refine.html (limited to 'doc/refine.html') diff --git a/doc/refine.html b/doc/refine.html new file mode 100644 index 0000000..cfe18b9 --- /dev/null +++ b/doc/refine.html @@ -0,0 +1,354 @@ + + + + refine + + + + +

tweak/refine

+

Summary

+ Refine creates an abstract + profile, by comparing CIE measurement values from two test charts. + The charts will usually be in .ti3 + format, but only XYZ, Lab or spectral values will be used (ie. all + device space values are ignored). Typically the charts would be + printed on a target system (the one being emulated, say a printing + press), and the proofing system (the one that is being profiled). + The abstract profile that refine + produces will be a correction that makes the proofing system behave + more like the target. This can then be used to recreate the proofing + systems ICC profile, or device link. By feeding a previous abstract + correction profile in as well, iterative improvement can be made to + the proofing reproduction.
+
+ verify is a useful tool to use on the two + test charts, to check how well the refinement is proceeding. If a + white point relative match is being created (refine -R), then use + veryify -N.
+

Usage Summary

+ usage: refine [-options] cietarget ciecurrent [outdevicc] + [inabs] outabs
+  -v            + + Verbose
+  -c            +Create + + initial abstract correction profile
+  -g            +Don't + + impose output device gamut limit
+  -r res        Set + abstract profile clut resolution (default 33)
+  -d factor     Override default damping + factor (default 0.950000)
+  -R            +Aim + + for white point relative match rather than absolute
+  -f + [illum]    Use Fluorescent Whitening Agent + compensation [opt. simulated inst. illum.:
+                 + + + M0, M1, M2, A, C, D50 (def.), D50M2, D65, F5, F8, F10 or + file.sp]
+  -i illum      Choose + illuminant for computation of CIE XYZ from spectral data + & FWA:
+                 + + + A, C, D50 (def.), D50M2, D65, F5, F8, F10 or file.sp
+  -o observ     Choose CIE Observer for + spectral data:
+                  +1931_2, + + 1964_10, S&B 1955_2, J&V 1978_2 (def.)
+  cietarget     + Target CIE or spectral values, CGATS file (e.g. .ti3)
+  ciecurrent    + Actual CIE or spectral values, CGATS file (e.g. .ti3)
+  [outdevicc]   + Output device ICC profile to set gamut limit (not used if -g)
+  [inabs]       +Previous + + abstract correction ICC profile (not used if -c)
+  outabs        +Created/refined + + abstract correction ICC profile
+

Usage Details

+ refine provides a way of improving the profile accuracy of a + proofing system.
+
+ The -v flag prints out extra information during the + checking, and prints each patch value, rather than just a summary.
+
+ The -c option is used when refine is being used for the + first time, and there is no previous abstract profile to continue + refining. If -c is used, + then the name of the previous abstract correction profile should not + be supplied.
+
+ If the -g flag indicates that an output device profile is + not being supplied, and that corrections should be attempted, even + if the colors are outside the devices gamut. Normally an output + device profile is supplied, and corrections aren't applied to colors + outside the devices gamut, since this will not achieve anything + useful, and can distort the results.
+
+ If the -r parameter overrides the resolution of the CLUT + grid used in the abstract profile. By default the value is 33, but + other
+ values can be chosen. An odd number is recommended.
+
+ If the -d parameter sets how aggressively refine should try + and correct errors. Normally it will try and exactly compensate for + the color errors revealed in comparing the two measurement files, + but if the device behaviour is unusual, or not very repeatable, this + may result in successive applications of refine making things worse, + rather than better. If this is the case, try using a smaller number, + such as 0.8, or 0.5.
+
+ If the -R flag is used, + then refine creates an abstract profile for improving the match of + the patch values when  interpreted in a white point relative + (ie. Relative Colorimetric) intent. If used to create a corrected + device link profile using collink, + remember to create a Relative colorimetric intent device link + profile.
+
+ The -f flag enables Fluorescent Whitening Agent (FWA) + compensation. This only works if spectral data is available and, the + instrument is not UV filtered.  FWA compensation adjusts the + spectral samples so that they appear to have been measured using an + illuminant that has a different level of Ultra Violet to the one the + instrument actually used in the measurement. The optional + illumination parameter allows specifying a standard or custom + illumination spectrum to be used as the similated instrument + illuminant, overriding the default D50 or CIE computation + illuminant used for FWA (see -i below). See colprof -f for + a fuller explanation. The same value should be used as was used + during the creation of the profile.
+
+ The -i flag allows specifying a standard or custom + illumination spectrum, applied to the spectral test point values to + compute CIE tristimulus values. A, D50, D50M2, + D65, F5, F8, F10 are a selection of + standard illuminant spectrums, with D50 being the default. + If a filename is specified instead, it will be assumed to be an + Argyll specific .sp + spectrum file. If FWA compensation is used during measurement, this + illuminant will be used by default as the simulated instrument + illuminant. The same value should be used as was used during the + creation of the profile.
+
+ The -o flag allows specifying a tristimulus observer, and is + used to compute CIE tristimulus values. The following choices are + available:
+   1931_2 selects the standard CIE 1931 2 degree + observer.
+   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
+
+ If both CIE and spectral values are present in the input files, the + CIE values will be used by default. Using the -i, -o or -f + flag will force spectral values to be used. The the -i, -o or -f + flags will apply to both the target and measured input files.
+
+ cietarget         +Is + + the filename of the target CIE or spectral values. This is a CGATS file (e.g. a .ti3 made using chartread). These are the color values + wanted for each patch in the test chart, typically the product of + the target print system.
+
+ ciecurrent +         Is the filename of the + actual, current measured CIE or spectral values. This is a CGATS file (e.g. a .ti3 made using chartread). The errors between these + patches and the patches in the cietarget file will be used to create a + correction profile.
+
+  [outdevicc]     +If + + the -g flag is not used, + then the output device ICC profile should be supplied here, to allow + refine to limit its + corrections to colors that are within the gamut of the device.
+
+  [inabs]           +After + + the first correction has been created, subsequent corrections need + to improve upon previous ones, so the previous correction profile + should be provided here. For the first correction, the -c flag should be used, and this + argument is omitted.
+
+  outabs            +The + + name of the created or refined abstract correction ICC profile
+
+

Discussion

+ Refine is typically used in + a proofing situation, in which a verification chart is being used to + check the accuracy of a proofing system. (It might also be used for + more arbitrary color alterations by created two test chart files by + hand.) By using the errors between the target chart and the measured + values, refine attempts to improve the match between the proofing + system and its target.
+
+ There is facility in collink, colprof and revfix + to incorporate an abstract profile.
+
+ For systems using two device profiles or a device link to convert + between the target space printing files and the proofing device + space, the following would be a typical scenario:
+
+
We have a reference set of test + chart values, read from the target system reference.ti3. The ICC profile + for the target system is target.icm. + The ICC profile for the proofing system is proofer.icm. If using a device + link, the device link used to print proofer test charts is + currently target_proofer.icm:
+
+
+ First we print the test chart out on the proofing system and read + it in, resulting in a chart1.ti3 + file.
+
+ Lets check how well the proofing system current matches using + verify:
+
+     verify  reference.ti3 chart1.ti3
+
+ We then create our initial abstract correction fix profile fix1.icm using refine:
+
+     refine -v -c  reference.ti3 chart1.ti3 + proofer.icm fix1.icm
+
+ Applying this to your process for creating the proofer device + profile or target to proofing device link (choose one of the three + options below, depending whether you are using the proofer profile + and just want to alter its colorimetric B2A table using revfix, whether you are going + to recreate the proofer file from the original measurement data + using  colprof, or + whether you are using a device link profile created using collink):
+
+     revfix -v -1 -ke -p fix1.icm proofer.icm + proofer_fix1.icm
+ or
+     copy proofer.ti3 proofer_fix1.ti3
+     colprof -v -p fix1.icm proofer_fix1
+ or
+     collink -v -s -ia -oa -p fix1.icm target.icm + proofer.icm target_proofer_fix1.icm
+
+ Note that the above example is a simple one - you should use all + the same options as you used to create your initial proofer.icm  + + or target_proofer.icm, + with the addition of the "-p fix1.icm" option to specify the + abstract correction profile be applied.
+
+ Use the proofer_fix1.icm + or target_proofer_fix1.icm + to print out the test chart again, and read it in, resulting in chart2.ti3 file.
+
+ Lets check how well the proofing system matches after this first + round of refinement using verify:
+
+     verify  reference.ti3 chart2.ti3
+
+
+ >>>
+
+  We +can + + then start another round of improvement:
+
+ We refine our previous abstract correction fix profile using + refine:
+
+     refine -v  reference.ti3 chart2.ti3 + proofer.icm fix1.icm fix2.icm
+
+ Applying this new abstract profile to our process for creating the + proofing device profile or link again:
+
+     revfix -v -1 -ke -p fix2.icm proofer.icm + proofer_fix2.icm
+ or
+     copy proofer.ti3 proofer_fix2.ti3
+     colprof -v -p fix2.icm proofer_fix2
+ or
+     collink -v -s -ia -oa -p fix2.icm target.icm + proofer.icm target_proofer_fix2.icm
+
+ Use the proofer_fix2.icm + or target_proofer_fix2.icm + to print out the test chart again, and read it in, resulting in chart3.ti3 file.
+
+ Check again how well the proofing system matches after this first + round of refinement using verify:
+
+     verify  reference.ti3 chart3.ti3
+
+ Rounds of improvements can be continues by looping back to >>>, being careful to + increment the names of the fixN.icm,  + + proofer_fixN.icm or target_proofer_fixN.icm and chartN.ti3files. Stop when + exhausted, or if it looks like things are getting worse, rather + than better. If the latter happens, it might be good to revert to + the results from a previous round.
+
+
+
+
+
+
+
+
+ + -- cgit v1.2.3