464 lines
18 KiB
HTML
Executable File
464 lines
18 KiB
HTML
Executable File
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<title>refine</title>
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<meta http-equiv="content-type" content="text/html;
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charset=windows-1252">
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<meta name="author" content="Graeme Gill">
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</head>
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<body>
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<h2><b>tweak/refine</b></h2>
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<h3>Summary</h3>
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<span style="font-weight: bold;">Refine</span> creates an abstract
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profile, by comparing CIE measurement values from two test charts.
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The charts will usually be in <a href="File_Formats.html#.ti3">.ti3</a>
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format, but only XYZ, Lab or spectral values will be used (ie. all
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device space values are ignored). Typically the charts would be
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printed on a target system (the one being emulated, say a printing
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press, or created using an ideal target profile such as Rec709), and
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the proofing system (the device that is being profiled). The
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abstract profile that <span style="font-weight: bold;">refine</span>
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produces will be a correction that makes the proofing system behave
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more like the target. This can then be used to recreate the proofing
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systems ICC profile, or device link. By feeding a previous abstract
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correction profile in as well, iterative improvement can be made to
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the proofing reproduction.<br>
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<br>
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<a href="colverify.html">colverify</a> is a useful tool to use on
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the two test charts, to check how well the refinement is proceeding.
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If a white point relative match is being created (refine -R), then
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use veryify -N.<br>
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<h3>Usage Summary</h3>
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<tt>usage: refine [-options] cietarget ciecurrent [outdevicc]
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[inabs] outabs</tt><tt><br>
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</tt><tt>
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-v
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Verbose</tt><tt><br>
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</tt><tt>
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-c
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Create
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initial abstract correction profile</tt><tt><br>
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</tt><tt>
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-g
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Don't
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impose output device gamut limit</tt><tt><br>
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</tt><tt> -r res Set
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abstract profile clut resolution (default 33)</tt><tt><br>
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</tt><tt> -d factor Override default
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damping factor (default 0.950000)</tt><tt><br>
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</tt><tt>
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-R
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Aim
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for white point relative match rather than absolute</tt><tt><br>
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</tt><tt> -f [illum] Use Fluorescent
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Whitening Agent compensation [opt. simulated inst. illum.:</tt><tt><br>
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</tt><tt>
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M0, M1, M2, A, C, D50 (def.), D50M2, D65, F5, F8, F10 or file.sp]</tt><tt><br>
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</tt><tt> -i illum Choose
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illuminant for computation of CIE XYZ from spectral data &
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FWA:</tt><tt><br>
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</tt><tt>
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A, C, D50 (def.), D50M2, D65, F5, F8, F10 or file.sp</tt><tt><br>
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</tt><tt> -o observ Choose CIE
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Observer for spectral data:</tt><tt><br>
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</tt><tt>
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1931_2,
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1964_10, 2015_2 (def.), 2015_10, S&B 1955_2, J&V 1978_2 or
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file.cmf</tt><tt><br>
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</tt><tt> cietarget Target CIE or
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spectral values, CGATS file (e.g. .ti3)</tt><tt><br>
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</tt><tt> ciecurrent Actual CIE or spectral
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values, CGATS file (e.g. .ti3)</tt><tt><br>
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</tt><tt> [outdevicc] Output device ICC profile to
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set gamut limit (not used if -g)</tt><tt><br>
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</tt><tt> [inabs] Previous
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abstract correction ICC profile (not used if -c)</tt><tt><br>
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</tt><tt> outabs
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Created/refined abstract correction ICC profile</tt><br>
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<h3>Usage Details</h3>
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<b>refine</b> provides a way of improving the profile accuracy of a
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proofing system.<br>
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<br>
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The <b>-v</b> flag prints out extra information during the
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checking, and prints each patch value, rather than just a summary.<br>
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<br>
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The <b>-c</b> option is used when refine is being used for the
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first time, and there is no previous abstract profile to continue
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refining. If <span style="font-weight: bold;">-c</span> is used,
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then the name of the previous abstract correction profile should not
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be supplied.<br>
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<br>
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If the <b>-g </b>flag indicates that an output device profile is
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not being supplied, and that corrections should be attempted, even
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if the colors are outside the devices gamut. Normally an output
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device profile is supplied, and corrections aren't applied to colors
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outside the devices gamut, since this will not achieve anything
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useful, and can distort the results.<br>
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<br>
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If the <b>-r </b>parameter overrides the resolution of the CLUT
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grid used in the abstract profile. By default the value is 33, but
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other<br>
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values can be chosen. An odd number is recommended. <br>
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<br>
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If the <b>-d </b>parameter sets how aggressively refine should try
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and correct errors. Normally it will try and exactly compensate for
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the color errors revealed in comparing the two measurement files,
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but if the device behaviour is unusual, or not very repeatable, this
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may result in successive applications of refine making things worse,
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rather than better. If this is the case, try using a smaller number,
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such as 0.8, or 0.5.<br>
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<br>
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If the <span style="font-weight: bold;">-R</span> flag is used,
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then refine creates an abstract profile for improving the match of
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the patch values when interpreted in a white point relative
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(ie. Relative Colorimetric) intent. If used to create a corrected
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device link profile using <a href="collink.html">collink</a>,
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remember to create a Relative colorimetric intent device link
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profile.<br>
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<br>
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The <b>-f</b> flag enables Fluorescent Whitening Agent (FWA)
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compensation. This only works if spectral data is available and, the
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instrument is not UV filtered. FWA compensation adjusts the
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spectral samples so that they appear to have been measured using an
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illuminant that has a different level of Ultra Violet to the one the
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instrument actually used in the measurement. The optional
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illumination parameter allows specifying a standard or custom
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illumination spectrum to be used as the similated instrument
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illuminant, overriding the default <b>D50</b> or CIE computation
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illuminant used for FWA (see <b>-i</b> below<b>). </b>See <a
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href="colprof.html#f">colprof -f</a> for a fuller explanation. The
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same value should be used as was used during the creation of the
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profile.<br>
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<br>
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The <b>-i</b> flag allows specifying a standard or custom
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illumination spectrum, applied to the spectral test point values to
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compute CIE tristimulus values. <b>A</b>, <b>D50</b>, <b>D50M2,
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D65</b>, <b>F5</b>, <b>F8</b>, <b>F10</b> are a selection of
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standard illuminant spectrums, with <b>D50</b> being the default.
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If a filename is specified instead, it will be assumed to be an
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Argyll specific <a href="File_Formats.html#.sp">.sp</a> spectrum
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file. If FWA compensation is used during measurement, this
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illuminant will be used by default as the simulated instrument
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illuminant. The same value should be used as was used during the
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creation of the profile.<br>
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<br>
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The <b>-o</b> flag allows specifying a tristimulus observer, and is
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used to compute CIE tristimulus values. The following choices are
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available:<br>
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<b> 1931_2</b> selects the standard CIE 1931 2 degree
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observer.<br>
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<b>1964_10</b> selects the standard CIE 1964 10 degree
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observer.<br>
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<b> 2015_2</b> selects the standard CIE 2015 2 degree observer<br>
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<b>2015_10</b> selects the standard CIE 2015 10 degree
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observer<br>
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<b>1955_2</b> selects the Stiles and Birch 1955 2 degree
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observer<br>
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<b>1978_2 </b>selects the Judd and Voss 1978 2 degree
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observer<br>
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<b>shaw</b> selects the Shaw and Fairchild 1997 2 degree
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observer<br>
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<i><b>file.cmf</b></i> selects an observer specified by the
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given <a href="File_Formats.html#.cmf">.cmf</a> file.<br>
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<br>
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If both CIE and spectral values are present in the input files, the
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CIE values will be used by default. Using the <span
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style="font-weight: bold;">-i</span>, <span style="font-weight:
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bold;">-o</span> or <span style="font-weight: bold;">-f</span>
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flag will force spectral values to be used. The the <span
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style="font-weight: bold;">-i</span>, <span style="font-weight:
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bold;">-o</span> or <span style="font-weight: bold;">-f</span>
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flags will apply to both the target and measured input files.<br>
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<br>
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<span style="font-style: italic; font-weight: bold;">cietarget</span>
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Is
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the filename of the target CIE or spectral values. This is a <a
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href="File_Formats.html#CGATS">CGATS</a> file (e.g. a <a
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href="File_Formats.html#.ti3">.ti3</a> made using <a
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href="chartread.html">chartread</a>). These are the color values
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wanted for each patch in the test chart, typically the product of
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the target print system.<br>
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<br>
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<span style="font-style: italic; font-weight: bold;">ciecurrent</span>
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Is the filename of the
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actual, current measured CIE or spectral values. This is a <a
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href="File_Formats.html#CGATS">CGATS</a> file (e.g. a <a
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href="File_Formats.html#.ti3">.ti3</a> made using <a
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href="chartread.html">chartread</a>). The errors between these
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patches and the patches in the <span style="font-style: italic;
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font-weight: bold;">cietarget</span> file will be used to create a
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correction profile.<br>
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<br>
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[<span style="font-style: italic; font-weight: bold;">outdevicc</span>]
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If
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the <span style="font-weight: bold;">-g</span> flag is not used,
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then the output device ICC profile should be supplied here, to allow
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<span style="font-weight: bold;">refine</span> to limit its
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corrections to colors that are within the gamut of the device.<br>
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<br>
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[<span style="font-weight: bold; font-style: italic;">inabs</span>]
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After
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the first correction has been created, subsequent corrections need
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to improve upon previous ones, so the previous correction profile
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should be provided here. For the first correction, the <span
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style="font-weight: bold;">-c</span> flag should be used, and this
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argument is omitted.<br>
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<br>
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<span style="font-weight: bold; font-style: italic;">outabs</span>
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The
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name of the created or refined abstract correction ICC profile<br>
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<br>
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<h3> Discussion</h3>
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<span style="font-weight: bold;">Refine</span> is typically used in
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a proofing situation, in which a verification chart is being used to
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check the accuracy of a proofing system. (It might also be used for
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more arbitrary color alterations by created two test chart files by
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hand.) By using the errors between the target chart and the measured
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values, refine attempts to improve the match between the proofing
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system and its target.<br>
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<br>
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There is facility in <a href="collink.html">collink</a>, <a
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href="colprof.html">colprof</a> and <a href="revfix.html">revfix</a>
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to incorporate an abstract profile. <br>
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<br>
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For systems using two device profiles or a device link to convert
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between the target space printing files and the proofing device
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space, the following would be a typical scenario:<br>
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<br>
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<div style="margin-left: 40px;">We have a reference set of test
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chart values, read from the target system <span
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style="font-weight: bold;">reference.ti3</span>. The ICC profile
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for the target system is <span style="font-weight: bold;">target.icm</span>.
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The ICC profile for the proofing system is <span
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style="font-weight: bold;">proofer.icm</span>. If using a device
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link, the device link used to print proofer test charts is
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currently <span style="font-weight: bold;">target_proofer.icm</span>:<br>
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<br>
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<br>
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First we print the test chart out on the proofing system and read
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it in, resulting in a <span style="font-weight: bold;">chart1.ti3</span>
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file.<br>
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<br>
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Lets check how well the proofing system current matches using
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colverify:<br>
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<br>
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colverify reference.ti3 chart1.ti3<br>
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<br>
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We then create our initial abstract correction fix profile <span
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style="font-weight: bold;">fix1.icm</span> using refine:<br>
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<br>
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refine -v -c reference.ti3 chart1.ti3
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proofer.icm fix1.icm<br>
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<br>
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Applying this to your process for creating the proofer device
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profile or target to proofing device link (choose one of the three
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options below, depending whether you are using the proofer profile
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and just want to alter its colorimetric B2A table using <span
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style="font-weight: bold;">revfix</span>, whether you are going
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to recreate the proofer file from the original measurement data
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using <span style="font-weight: bold;">colprof</span>, or
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whether you are using a device link profile created using <span
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style="font-weight: bold;">collink</span>):<br>
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<br>
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revfix -v -1 -ke -p fix1.icm proofer.icm
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proofer_fix1.icm<br>
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or<br>
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copy proofer.ti3 proofer_fix1.ti3<br>
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colprof -v -p fix1.icm proofer_fix1<br>
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or<br>
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collink -v -s -ia -oa -p fix1.icm target.icm
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proofer.icm target_proofer_fix1.icm<br>
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<br>
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Note that the above example is a simple one - you should use all
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the same options as you used to create your initial <span
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style="font-weight: bold;"><span style="font-weight: bold;"></span>proofer.icm
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</span>or <span style="font-weight: bold;">target_proofer.icm</span>,
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with the addition of the "-p fix1.icm" option to specify the
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abstract correction profile be applied.<br>
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<br>
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Use the <span style="font-weight: bold;">proofer_fix1.icm</span>
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or <span style="font-weight: bold;">target_proofer_fix1.icm</span>
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to print out the test chart again, and read it in, resulting in <span
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style="font-weight: bold;">chart2.ti3</span> file.<br>
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<br>
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Lets check how well the proofing system matches after this first
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round of refinement using colverify:<br>
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<br>
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colverify reference.ti3 chart2.ti3<br>
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<br>
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<br>
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<span style="font-weight: bold;"><span style="font-weight: bold;">>>></span></span><br>
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<span style="font-weight: bold;"><span style="font-weight: bold;"></span></span><br>
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<span style="font-weight: bold;"><span style="font-weight: bold;"> </span></span>We
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can
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then start another round of improvement:<br>
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<br>
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We refine our previous abstract correction fix profile using
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refine:<br>
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<br>
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refine -v reference.ti3 chart2.ti3
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proofer.icm fix1.icm fix2.icm<br>
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<br>
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Applying this new abstract profile to our process for creating the
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proofing device profile or link again:<br>
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<br>
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revfix -v -1 -ke -p fix2.icm proofer.icm
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proofer_fix2.icm<br>
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or<br>
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copy proofer.ti3 proofer_fix2.ti3<br>
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colprof -v -p fix2.icm proofer_fix2<br>
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or<br>
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collink -v -s -ia -oa -p fix2.icm target.icm
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proofer.icm target_proofer_fix2.icm<br>
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<br>
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Use the <span style="font-weight: bold;">proofer_fix2.icm</span>
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or <span style="font-weight: bold;">target_proofer_fix2.icm</span>
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to print out the test chart again, and read it in, resulting in <span
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style="font-weight: bold;">chart3.ti3</span> file.<br>
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<br>
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Check again how well the proofing system matches after this first
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round of refinement using colverify:<br>
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<br>
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colverify reference.ti3 chart3.ti3<br>
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<br>
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Rounds of improvements can be continues by looping back to <span
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style="font-weight: bold;">>>></span>, being careful to
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increment the names of the <span style="font-weight: bold;">fixN.icm</span>,
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<span style="font-weight: bold;">proofer_fixN.icm</span> or <span
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style="font-weight: bold;">target_proofer_fixN.icm</span> and <span
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style="font-weight: bold;">chartN.ti3</span>files. Stop when
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exhausted, or if it looks like things are getting worse, rather
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than better. If the latter happens, it might be good to revert to
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the results from a previous round.<br>
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</div>
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<br>
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<br>
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<br>
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<br>
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<br>
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<br>
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<br>
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</body>
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</html>
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