253 lines
12 KiB
HTML
Executable File
253 lines
12 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>revfix</title>
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<meta http-equiv="content-type"
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content="text/html; charset=ISO-8859-1">
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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>xicc/revfix</b></h2>
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<h3>Summary</h3>
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Regenerate a CLUT device profiles B2A table data by inverting the A2B
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table.<br>
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<h3>Usage Summary</h3>
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<small><span style="font-family: monospace;">revfix [-options] iccin
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iccout</span><br style="font-family: monospace;">
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<span style="font-family: monospace;"> -v
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Verbose</span><br
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style="font-family: monospace;">
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<span style="font-family: monospace;"> -0
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Process perceptual</span><br
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style="font-family: monospace;">
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<span style="font-family: monospace;"> -1
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Process absolute/relative colorimetric</span><br
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style="font-family: monospace;">
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<span style="font-family: monospace;"> -2
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Process saturation</span><br
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style="font-family: monospace;">
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<span style="font-family: monospace;"> -r res
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Override BtoA1
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CLUT res.</span><br style="font-family: monospace;">
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<span style="font-family: monospace;"> </span><a
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style="font-family: monospace;" href="#k">-k</a><span
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style="font-family: monospace;"> [ezhxr]
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e =
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same K as existing BtoA table (def)</span><br
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style="font-family: monospace;">
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<span style="font-family: monospace;">
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z =
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zero, h = 0.5 K, x = max K, r = ramp K</span><br
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style="font-family: monospace;">
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<span style="font-family: monospace;"> </span><a
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style="font-family: monospace;" href="#kp">-k p stle stpo enle enpo
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shape</a><br style="font-family: monospace;">
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<span style="font-family: monospace;">
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p =
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curve parameters</span><br style="font-family: monospace;">
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<span style="font-family: monospace;">
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stle: K
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level at White 0.0 - 1.0</span><br style="font-family: monospace;">
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<span style="font-family: monospace;">
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stpo:
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start point of transition Wh 0.0 - Bk 1.0</span><br
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style="font-family: monospace;">
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<span style="font-family: monospace;">
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enpo:
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End point of transition Wh 0.0 - Bk 1.0</span><br
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style="font-family: monospace;">
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<span style="font-family: monospace;">
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enle: K level at Black 0.0 - 1.0</span><br
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style="font-family: monospace;">
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<span style="font-family: monospace;">
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shape:
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1.0 = straight, 0.0-1.0 concave, 1.0-2.0
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convex</span><br style="font-family: monospace;">
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<span style="font-family: monospace;"> </span><a
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style="font-family: monospace;" href="#K">-K parameters</a><span
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style="font-family: monospace;"> Same as
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-k, but
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target is K locus rather than K value itself</span><br
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style="font-family: monospace;">
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<span style="font-family: monospace;"> </span><a
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style="font-family: monospace;" href="#l">-l tlimit</a><span
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style="font-family: monospace;">
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set total ink limit, 0
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- 400%
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(estimate by default)</span><br style="font-family: monospace;">
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<span style="font-family: monospace;"> </span><a
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style="font-family: monospace;" href="#L">-L klimit</a><span
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style="font-family: monospace;">
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set black ink limit, 0
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- 100%
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(estimate by default)</span><br style="font-family: monospace;">
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<span style="font-family: monospace;"> </span><a
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style="font-family: monospace;" href="#p">-p aprof.icm</a><span
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style="font-family: monospace;">
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Include abstract
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profile in output tables</span></small><br>
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<h3>Usage Details and Discussion</h3>
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Existing ICC profiles may not contain accurately inverted AtoB table
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data in their B2A tables, and this tool provides a means of
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addressing this, or regenerating the B2A information with a different
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black generation and/or ink limit, or applying an abstract correction
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profile to the B2A table, without completely recreating the profile.<br>
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<br>
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Currently <b>revfix</b> does not support creating real perceptual or
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saturation B2A tables, but can only create relative colorimetric
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tables. It also will not handle CLUT profile that use a matrix element
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in them.<br>
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<br>
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<b>-v</b> Turn on verbose mode. Gives progress information as the
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table is created. Since B2A tables can take a long time to generate,
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this is often useful to monitor progress.<br>
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<br>
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The B2A table to be re-creating can be specified by using the <b>-0</b>,
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<b>-1</b>, and <b>-2</b>f lags. Normally only the <b>-1</b> flag
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should be specified, but the perceptual and saturation tables can be
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replaces instead/as well, if their respective flags are specified.<br>
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<br>
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Normally the re-created B2A table will have the same CLUT resolution as
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the existing table, but this can be overridden by using the <b>-r</b>
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flag.
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Typically a resolution of 9 might be used for a medium quality CMYK
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table,
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with 17 being used for a high quality CMYK table. For an RGB profile, a
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resolution of 17 might be used for a medium quality table, and 33 being
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used for a high quality table.<br>
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<tt></tt><br>
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<a name="k"></a> -<b>k</b> parameter sets the target level of black (K)
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when creating a B2A CMYK output tables. This is often called a black
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level, a black inking rule, black generation, or under color
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removal. These set the target black level.<br>
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<br>
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Possible arguments to the <b>-k</b> flag are:<br>
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<br>
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<b> -kz</b> selects minimum black (0.0)<br>
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<b> -kh</b> selects a black value of 0.5<br>
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<b> -kx</b> selects the maximum possible black (1.0)<br>
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<b> -kr</b> selects a linear black ramp, starting at minimum black for
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highlight, and maximum black for shadow (equivalent to -kp 0 0 1 1 1).
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This is the default.<br>
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<br>
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<b><a name="kp"></a>-k p stle stpo enpo enle shape</b> allows an
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arbitrary black value ramp to be defined, consisting of a starting
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value (stle) for highlights, a breakpoint L value (stpo) where it
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starts to transition to the shadow level, an end breakpoint L (enpo)
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where it flattens out again, and the finishing black level (enle) for
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the shadows. There is also a curve parameter, that modifies the
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transition from stle to enle to either be concave (ie. the
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transition starts gradually and and finished more abruptly) using
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values 0.0-1.0, with 0.0 being most concave, or convex (the transition
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starts more abruptly but finishes gradually), using values 1.0-2.0,
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with 2.0 being the most convex.<br>
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<br>
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Typical black value generation curve with parameters something
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like: -kp 0 .1 .9 1 .5<br>
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<br>
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<tt> 1.0 K |
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enpo<br>
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| _______
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enle<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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stle
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| ------/<br>
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+-------------------<br>
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0.0 K
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0.0 stpo 1.0<br>
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White
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Black<br>
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</tt>
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<br>
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For minimum sensitivity of printed output to the lighting spectrum, it
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currently seems best to use the maximum possible black, but other black
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generation levels (ie. 0.3 to 0.5) may well be preferred if one wants
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to
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minimize the noisy appearance of black on an inkjet device, or
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if the banding behaviour or other rendering flaws of the printer is to
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be minimized. <br>
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<br>
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The <a href="xicclu.html">xicclu</a> tool can be used to plot out
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the resulting black level for a given set of parameters, by using the <a
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href="xicclu.html#g">-g</a> flag of a profile already created from the
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same .ti3 file.<br>
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<br>
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<a name="K"></a> <span style="font-weight: bold;">-K parameters.</span>
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Any of the <span style="font-weight: bold;">-k</span> options above
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can use the <span style="font-weight: bold;">-K</span> version, in
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which rather than a black value target being defined by the inking
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rule, a black <span style="text-decoration: underline;">locus</span>
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target is defined. For each lookup, the minimum possible black level
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and the maximum possible black level is determined, the former
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corresponding to a locus target of 0, and the latter corresponding to a
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locus target of 1. For instance, at
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the
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white point, no black will be used in the output, even if the black
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locus specifies a maximum (since the maximum amount of black that
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can be used to print white is actually zero). Similarly, at the black
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point, black may well be used, even if the black locus specifies
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zero black (since a certain amount of black is needed to achieve the
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desired density of color). <br>
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<tt> </tt><br>
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<a name="l"></a>The <b>-l</b> <i>tlimit</i> parameter sets the ink
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limit (TAC, Total
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Area Coverage) for the CMYK separation, as a total percentage from 0%
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to 400%. By default, this value will be estimated from the profile. The
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limit value should generally be set a little below the value used in
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the test chart
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generation, to avoid the very edges of the gamut. If the test chart ink
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limit has been chosen to be a little beyond an acceptable level, then
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this
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number should be the acceptable level. Although limits can be set below
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200%, this will generally restrict the color gamut noticeably, as fully
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saturated
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secondary colors will not be reproduced. Values are between 220% and
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300%
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for typical printing devices. The ink limit
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will be in final raw device values if the profile includes
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calibration information.<br>
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<br>
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<br>
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<a name="L"></a> The <b>-L</b> <i>klimit</i> parameter sets the black
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channel ink limit for the CMYK separation, as a total percentage from
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0%
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to 100%. By default, this value will be estimated from the profile. For
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printing press like devices, this can be used to prevent
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the
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black channel screening pattern "filling in". Typical values might be
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from
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95% to 99%. The ink limit
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will be in final raw device values if the profile includes
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calibration information.<br>
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<br>
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<br>
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The <b><a name="p"></a>-p</b> option allows specifying an abstract
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profile be applied to all of the output tables. An abstract
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profile is a way of specifying a color adjustment in a device
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independent way. The abstract profile might have been created using one
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of the <span style="font-weight: bold;">tweak</span> tools, such as <a
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href="refine.html">refine</a>.<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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