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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>collink</title>
<meta http-equiv="content-type" content="text/html;
charset=ISO-8859-1">
<meta name="author" content="Graeme Gill">
</head>
<body>
<h2><b>link/collink</b></h2>
<h3>Summary</h3>
Link two ICC device profiles to create an ICC device link profile.<br>
<br>
<b> collink</b> takes two device ICC profiles, and links them
together, either in a simple fashion using the standard ICC forward
and reverse tables of the specified intent, or using color
appearance space and true gamut mapping, together with possibly
inverting the forward profile, to allow black ink regeneration
or to retain the source black characteristic from the source
profile.<br>
<h3>Usage Summary</h3>
<small><span style="font-family: monospace;">collink [-options] <span
style="font-style: italic;">srcprofile dstprofile
linkedprofile</span></span><br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#v">-v</a><span
style="font-family: monospace;">
Verbose<br>
</span></small><small><span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#A">-A "manufacturer"</a><span
style="font-family: monospace;"> Set the manufacturer
description string</span><br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#M">-M "model"</a><span
style="font-family: monospace;">
Set the model
description string</span><br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#D">-D "description"</a><span
style="font-family: monospace;"> Set the profile
Description string (Default "</span><span
style="font-style: italic; font-family: monospace;">inoutfile</span><span
style="font-family: monospace;">")</span><br style="font-family:
monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#C">-C "copyright"</a><span
style="font-family: monospace;"> Set the
copyright string</span></small><br style="font-family:
monospace;">
<small><span style="font-family: monospace;"></span><span
style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#V">-V</a><span
style="font-family: monospace;">
Verify
existing
profile, rather than link (Debug option)</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#q">-q lmhu</a><span
style="font-family: monospace;">
Quality - Low, Medium (def),
High, Ultra</span><br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#r">-r <i>res</i></a><span
style="font-family: monospace;">
Override
clut
res. set by -q</span><br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#n">-n</a><span
style="font-family: monospace;">
Don't
preserve
device curves in result</span><br style="font-family:
monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#f">-f</a><span
style="font-family: monospace;">
Special :- Force neutral colors
to be K only output.<br>
</span></small><small><span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#fk">-fk</a><span
style="font-family: monospace;">
Special :- Force K only neutral colors
to be K only output<br>
</span></small><small><span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#fcmy">-fcmy</a><span
style="font-family: monospace;">
Special :- Force 100% C,M or Y only to stay pure</span></small><br
style="font-family: monospace;">
<small><span style="font-family: monospace;"></span><span
style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#F">-F</a><span
style="font-family: monospace;">
Special :- Force all colors to be
K only output.</span><br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#p">-p aprof.icm</a><span
style="font-family: monospace;">
Include
abstract profile in link</span><br style="font-family:
monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#s">-s</a><span
style="font-family: monospace;">
Simple
Mode
(default)</span><br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#g">-g [src.gam]</a><span
style="font-family: monospace;">
Gamut Mapping Mode [optional source image gamut]</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#G">-G [src.gam]</a><span
style="font-family: monospace;">
Gamut
Mapping Mode using inverse outprofile A2B [optional source
gamut]</span><br style="font-family: monospace;">
<br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><u
style="font-family: monospace;">Simple Mode Options:</u><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#si">-i <i>in_intent</i></a><span
style="font-family: monospace;"> p =
perceptual, r = relative colorimetric,</span><br
style="font-family: monospace;">
<span style="font-family: monospace;">
s
= saturation, a = absolute colorimetric</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#so">-o </a><i
style="font-family: monospace;"><a href="#so">out_intent</a> </i><span
style="font-family: monospace;"> p =
perceptual, r = relative colorimetric,</span><br
style="font-family: monospace;">
<span style="font-family: monospace;">
s
= saturation, a = absolute colorimetric</span><br
style="font-family: monospace;">
<br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><u
style="font-family: monospace;">Mapping Mode Options:</u><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#i">-i <i>intent</i></a><span
style="font-family: monospace;">
set linking intent from the following choice:</span><br
style="font-family: monospace;">
<span style="font-family: monospace;">
a
-
Absolute Colorimetric (in Jab) [ICC Absolute Colorimetric]<br>
aw
-
Absolute Colorimetric (in Jab) with scaling to fit white point<br
style="font-family: monospace;">
</span><span style="font-family: monospace;">
aa
-
Absolute Appearance</span><br style="font-family: monospace;">
<span style="font-family: monospace;">
r
-
White Point Matched Appearance [ICC Relative Colorimetric]</span><br
style="font-family: monospace;">
<span style="font-family: monospace;">
la
-
Luminance matched Appearance</span><br style="font-family:
monospace;">
<span style="font-family: monospace;">
p
-
Perceptual (Preferred) [ICC Perceptual]<br>
</span></small><small><span style="font-family: monospace;">
pa
- Perceptual Appearance</span></small><br style="font-family:
monospace;">
<small><span style="font-family: monospace;"></span><span
style="font-family: monospace;">
ms
-
Saturation</span><br style="font-family: monospace;">
<span style="font-family: monospace;">
s
-
Enhanced Saturation [ICC Saturation]</span><br
style="font-family: monospace;">
<span style="font-family: monospace;">
al
-
Absolute Colorimetric (Lab)</span><span style="font-family:
monospace;"></span><br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#w">-w [J,a,b]</a><span
style="font-family: monospace;"> Use forced
whitepoint hack [optional color to map the white to]</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#c">-c <i>viewcond</i></a><span
style="font-family: monospace;"> set source viewing
conditions for CIECAM02,</span><br style="font-family:
monospace;">
<span style="font-family: monospace;">
either
an enumerated choice, or a parameter</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#d">-d <i>viewcond</i></a><span
style="font-family: monospace;"> set destination
viewing conditions for CIECAM02,</span><br style="font-family:
monospace;">
<span style="font-family: monospace;">
either
an enumerated choice, or a parameter:value change<br>
</span></small><small><span style="font-family: monospace;">
pp - Practical
Reflection Print (ISO-3664 P2)</span><br style="font-family:
monospace;">
<span style="font-family: monospace;">
pe - Print evaluation environment (CIE 116-1995)<br>
</span></small><small><span style="font-family: monospace;">
pc - Critical print evaluation environment (ISO-3664 P1)</span></small><small><span
style="font-family: monospace;"></span><span style="font-family:
monospace;"></span><span style="font-family: monospace;"></span><span
style="font-family: monospace;"></span><br style="font-family:
monospace;">
<span style="font-family: monospace;">
mt - Monitor in
typical work environment</span><br style="font-family:
monospace;">
<span style="font-family: monospace;">
mb - Monitor in bright work environment</span><br
style="font-family: monospace;">
<span style="font-family: monospace;">
md - Monitor in darkened work
environment</span><br style="font-family: monospace;">
<span style="font-family: monospace;">
jm - Projector in dim
environment</span><br style="font-family: monospace;">
<span style="font-family: monospace;">
jd - Projector in dark
environment</span><br style="font-family: monospace;">
<span style="font-family: monospace;">
pcd - Photo CD - original scene
outdoors</span><br style="font-family: monospace;">
<span style="font-family: monospace;">
ob - Original scene - Bright
Outdoors</span><br style="font-family: monospace;">
<span style="font-family: monospace;">
cx - Cut Sheet Transparencies
on a viewing box</span><br style="font-family: monospace;">
<span style="font-family: monospace;">
s:surround
n
= auto, a = average, m = dim, d = dark,</span><br
style="font-family: monospace;">
<span style="font-family: monospace;">
c = transparency (default average)</span><br style="font-family:
monospace;">
<span style="font-family: monospace;">
w:X:Y:Z
Adapted
white point as XYZ (default media white)</span><br
style="font-family: monospace;">
<span style="font-family: monospace;">
w:x:y
Adapted
white point as x, y</span><br style="font-family: monospace;">
<span style="font-family: monospace;">
a:adaptation
Adaptatation
luminance in cd.m^2 (default 50.0)</span><br style="font-family:
monospace;">
<span style="font-family: monospace;">
b:background
Background
%
of image luminance (default 20)<br>
l:scenewhite
Scene white in cd.m^2 if surround = auto (default 250)<br
style="font-family: monospace;">
</span><span style="font-family: monospace;">
f:flare
Flare
light
% of image luminance (default 1)</span><br style="font-family:
monospace;">
<span style="font-family: monospace;">
f:X:Y:Z
Flare
color as XYZ (default media white)</span><br style="font-family:
monospace;">
<span style="font-family: monospace;">
f:x:y
Flare
color as x, y</span><br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#t">-t <i>tlimit</i></a><span
style="font-family: monospace;">
set
source
total ink limit, 0 - 400% (estimate by default)</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#T">-T <i>klimit</i></a><span
style="font-family: monospace;">
set
source
total ink limit, 0 - 100% (estimate by default)</span><br
style="font-family: monospace;">
<br style="font-family: monospace;">
<span style="font-family: monospace;"> </span><u
style="font-family: monospace;">Inverse outprofile A2B Options:</u><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#k">-k tezhxr</a><span
style="font-family: monospace;">
CMYK Black generation</span><br
style="font-family: monospace;">
<span style="font-family: monospace;">
t
= transfer K from source to destination, e = retain K of
destination B2A table</span><br style="font-family: monospace;">
<span style="font-family: monospace;">
z
= zero K, h = 0.5 K, x = maximum K, r = ramp K (default)</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#kp">-k p stle stpo enpo
enle shape</a><br style="font-family: monospace;">
<span style="font-family: monospace;">
p
= black level generation curve parameters</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#kq">-k q stle0 stpo0
enpo0 enle0 shape0 stle2 stpo2 enpo2 enle2 shape2</a><br
style="font-family: monospace;">
<span style="font-family: monospace;">
q
= transfer source K to dual curve limits</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#K">-K parameters</a><span
style="font-family: monospace;">
Same as -k, but target is K locus rather than K value itself</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#l">-l <i>tlimit</i></a><span
style="font-family: monospace;">
set
destination
total ink limit, 0 - 400% (estimate by default)</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"> </span><a
style="font-family: monospace;" href="#L">-L <i>klimit</i></a><span
style="font-family: monospace;">
set
destination
total ink limit, 0 - 100% (estimate by default)<br>
</span></small> <small><span style="font-family:
monospace;"><a href="#P">-P</a>
Create
gamut
gammap_p.wrl and gammap_s.wrl diagostics</span></small><small><br>
<br>
<span style="font-family: monospace;"></span></small><span
style="font-family: monospace;"> <span
style="text-decoration: underline;"><span style="font-style:
italic;"></span></span></span><a href="#p1"><i
style="font-family: monospace;">srcprofile</i></a><span
style="font-family: monospace;">
source
ICC
profile. A </span><small><span style="font-family: monospace;">TIFF
or JPEG file with embedded profile may be used here.</span></small><br
style="font-family: monospace;">
<span style="font-family: monospace;"><span
style="text-decoration: underline;"><span style="font-style:
italic;"></span></span></span><a href="#p2"><i
style="font-family: monospace;">dstprofile</i></a><span
style="font-family: monospace;">
destination
ICC
profile. </span><span style="font-family: monospace;">A </span><small><span
style="font-family: monospace;">TIFF or JPEG file with embedded
profile may be used here.</span></small><br style="font-family:
monospace;">
<span style="font-family: monospace;"> </span><a href="#p3"><i
style="font-family: monospace;">linkedprofile</i></a><span
style="font-family: monospace;">
resulting device link profile</span><br>
<h3>Usage Details and Discussion</h3>
<b><a name="v"></a> -v</b> Turns on verbose mode. Gives progress
information as the profile is created. Since gamut map mode inverse
profile linking can take a long time to perform, this is often
useful. <br>
<br>
<a name="A"></a>The <b>-A</b> parameter allows setting of the
device manufacturer description tag. This parameter may not be
relevant for a link profile, but if used should be a string that
identifies the manufacturer of the primary device used in the link.
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 parameters. By
default no manufacturer description string tag will be generated for
the profile.<br>
<br>
<a name="M"></a>The <b>-M</b> parameter allows setting of the
device mode description tag. This parameter may not be relevant for
a link profile, but if used should be a string that identifies the
particular model of primary device used in the link. 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 parameters. By default no model
description string tag will be generated for the profile.<br>
<br>
<a name="D"></a>The <b>-D</b> parameter allows setting of the
profile description tag. The parameter should be a string that
describes the profile. On many systems, it will be this string that
will be used to identify the profile from a list of possible
profiles. 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 base name of the resulting profile will be used as the
description.<br>
<br>
<a name="C"></a>The <b>-C</b> parameter allows setting of the
profile copyright tag. The parameter should be a string that
describes the copyright (if any) claimed on the profile being
generated.. 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
parameters. By default a generic copyright string will be generated
for the profile.<br>
<br>
<br>
<b><a name="V"></a> -V</b> Verifies an existing profile. This is
really a debugging option. It is only useful if all the linking
parameters are identical to those used during the creation of the
profile being verified.<br>
<br>
<b><a name="q"></a> -q [lmhu]</b> Quality
- Low, Medium (def), High, Ultra<br>
<b><a name="r"></a> -r res </b>
Override clut res. set by <b>-q</b><br>
<br>
This sets the basic quality of the resulting link, by choosing the
resolution of various tables in the resulting profile, as well as
the resolution of other temporary tables used in creating the link.
The <b>-r</b> flag allows overriding the resolution set by the <b>-q</b>
option, for the ICC profile CLUT multi-dimensional interpolation
table. It is highly recommended that <span style="font-weight:
bold;">-qm</span> be used as a starting point, and other settings
only tried after this has been evaluated. <span style="font-weight:
bold;">-qu</span> should almost never be used, except to prove
that it should almost never be used.<br>
<br>
<a name="n"></a>Normally the per channel device curves in the source
and destination profiles are preserved in the resulting device link
profile, but the <b>-n</b> option disables this. This can be useful
if the device linearisation curves are inappropriate in nature.<br>
<br>
<a name="f"></a> The <b>-f</b> option is a special purpose flag
useful only for 3 or 4 component (RGB, CMY or CMYK) source to CMYK
destination linking, that causes the destination to be <span
style="font-weight: bold;">K only</span> for neutral axis input.
Neutral axis input is assumed for R=G=B or C=M=Y input values. So as
to get a smooth mapping from the source to the K only destination,
by default the gamut mapping will be adjusted to target the
destination K only black, and Perceptual gamut mapping will be
selected along with maximum K inking. If other options are selected
that conflict with achieving a smooth mapping, warnings messages
will be emitted.<br>
<br>
<a name="F"></a> The <b>-F</b> option is a special purpose flag
useful only mapping to a CMYK destination, that causes the
destination to be converted to K only monochrome. So as to get a
smooth mapping from the source to the K only destination, by default
the gamut mapping will be adjusted to target the destination K only
black, and Perceptual gamut mapping will be selected along with
maximum K inking. If other options are selected that conflict with
achieving a smooth mapping, warnings messages will be emitted.<br>
<br>
<a name="fk"></a> The <b>-fk</b> option is a special purpose
flag useful only for CMYK source to CMYK destination linking, that
causes K only source values to map to K only destination values.
This is often useful in re-targeting CMYK material while preserving
K only text and graphics. So as to get a smooth mapping from the
source to the K only destination, by default the gamut mapping will
be adjusted to assume K only black source to destination K only
black for K only values, and Perceptual gamut mapping will be
selected along with a black generation rule (<span
style="font-weight: bold;">-kt</span>) that preserves the black
level from source to destination. If other options are selected that
conflict with achieving a smooth mapping, warnings messages will be
emitted.<br>
<br>
<a name="fcmy"></a> The <b>-fcmy</b> options are special
purpose flags useful only for CMY or CMYK source to CMY or CMYK
destination linking. The <span style="font-weight: bold;">cmy</span>
flags may be used independently or in combination (ie. <span
style="font-weight: bold;">-fc, -fm, -fy, -fcm, -fcy, -fmy, -fcmy</span>)
or combined with the <span style="font-weight: bold;">-fk</span>
option. These flags ensure that the pure 100% primary colorant
source values map to 100% pure colorant destination values, and may
be useful in some situations where CMYK material is being
re-targeted. <span style="font-weight: bold;">Note</span> that
forcing the 100% colorant values to map this way largely works
against the aims of color management in preserving colors
appearance. So as to get a smooth mapping from the source
to destination, by default the gamut mapping will a Saturation
intent with 100 percept alignment of the selected C, M and/or Y cusp
values. A Saturation intent is often what is desired in such CMYK to
CMYK re-renderings, as it makes best use of the (usually quite
similar sized) destination gamut. If other options are selected that
conflict with achieving a smooth mapping, warnings messages will be
emitted.<br>
<br>
<a name="p"></a> The <b>-p</b> option alows specifying an abstract
profile be applied between the source and destination profiles. An
abstract profile is a way of specifying a color adjustment in a
device independent way. The abstract profile might have been created
using one of the <span style="font-weight: bold;">tweak</span>
tools, such as <a href="refine.html">refine</a>.<br>
<br>
The basic linking style is chosen by using the <b>-s</b> (default),
<b>-g</b> or <b>-G</b> flags. The three behaviors are:<br>
<br>
<a name="s"></a> <b>-s</b> Simple mode. No gamut
mapping is performed, the selected intent AtoB and BtoA tables are
simply concatenated to create the output link, with the gamut
mapping behavior being determined solely by the BtoA table. The -i
and -o options allow selection of the source and destination ICC
intents. This is typically how other CMS do ICC linking. <a
href="#ss">Details</a>.<br>
<br>
<a name="g"></a> <b>-g</b> Gamut mapping mode. In
this mode, the absolute colorimetric AtoB and BtoA tables are used
to perform the link, and the intermediate linking color space is
(generally) the CIECAM02 Jab appearance space. The source and
destination viewing conditions can be selected using the <b>-c</b>
and <b>-d</b> options. A gamut mapping is performed between the two
spaces, using the intent selected by the <b>-i</b> option.
There is an optional argument, which is a source gamut to use
instead of that of the source profile. This is to allow optimizing
the gamut mapping to a source gamut of a particular image,
which can give slightly better results that gamut mapping from the
gamut of the source colorspace. Such a source image gamut can be
created using the <a href="tiffgamut.html"> tiffgamut</a> tool.
More <a href="#gg">details</a> about gamut mapping mode.<br>
<br>
<a name="G"></a> <b>-G</b> Use the gamut mapped, inverse
AtoB table linking method. This is generally the most accurate,
smooth and flexible linking method, but takes the longest to
perform. The gamut mapping mode (<span style="font-weight:
bold;">-g</span>) options <b>-i</b>, <b>-c</b>, <b>-d</b>, <b>-k</b>
and <b>-l</b> are effective when this method is selected. There is
an optional argument, which is a source gamut to use instead of that
of the source profile. This is to allow optimizing the gamut mapping
to a source gamut of a particular image, which can give
slightly better results that gamut mapping from the gamut of the
source colorspace. Such a source image gamut can be created using
the <a href="tiffgamut.html"> tiffgamut</a> tool. More <a
href="#GG">details</a> about the gamut mapping, inverse AtoB mode.<br>
<br>
The gamut provided to the <span style="font-weight: bold;">-g</span>
or <span style="font-weight: bold;">-G</span> flag should be in the
same colorspace that <span style="font-weight: bold;">collink</span>
is using internally to connect the two profiles. For all intents
except the last one (no. <span style="font-weight: bold;">7</span>),
the space should be Jab appearance space, with the viewing
conditions generally being those of the source profile viewing
conditions. The source profile will normally be the one used to
create a source image gamut using <span style="font-weight: bold;">tiffgamut</span>.<br>
<br>
<u><a name="ss"></a> Simple mode gamut mapping options:</u><br>
<br>
<a name="si"></a> <b>-i</b> <i>in_intent</i>
<b>p</b> = perceptual, <b>r</b> = relative colorimetric,<br>
<b>s</b>
= saturation, <b>a</b> = absolute colorimetric<br>
<a name="so"></a> <b>-o</b> <i>out_intent</i>
<b>p</b> = perceptual, <b>r</b> = relative
colorimetric,<br>
<b>s</b>
= saturation, <b>a</b> = absolute colorimetric<br>
<br>
These two options simply select the appropriate ICC table, according
to desired intent. Generally, it is a good idea to use the same
intent for both source and destination. Not all ICC profiles support
all four intents.<br>
<br>
<u><a name="gg"></a> Gamut mapping mode options:</u><br>
<br>
<a name="i"></a> <b>-i</b> <i>intent</i><br>
<br>
Select the gamut mapping intent. In gamut mapping mode there is only
a single overall intent. The intent is selected using the 1 two
letter option parameter, the standard ICC profile being a subset of
the available selections.<br>
<br>
<div style="margin-left: 40px;"><a name="ia"></a>The <span
style="font-weight: bold;">a</span> intent, Absolute
Colorimetric, is intended to reproduce colors exactly,
irrespective of the white point of the each medium. This is done
using CIECAM02 Jab appearance colorspace by forcing the source and
destination to have a common white point (but other aspects of the
individual viewing conditions are active), and colors are mapped
directly from source to destination, clipping any out of gamut
colors to the closest match. This is equivalent to the ICC <span
style="font-weight: bold;">Absolute Colorimetric</span> intent,
and is often used for proofing purposes. <br>
<br>
<a name="iaw"></a>The <span style="font-weight: bold;">aw</span>
intent, Absolute Colorimetric with scaling to fit white point, is
very similar to the <span style="font-weight: bold;">a</span>
intent, except that it will scale the source colorspace down in
order to make sure that the source white point isn't clipped by
the gamut of the destination. This might be used in some print
proofing situations where the source white is lightly lighter than
the destination white (as an alternative to using the <a
href="#w">-w</a> flag), or it may be useful in some soft
proofing situations where the differences in white point of the
display destination would cause clipping of the source white
point. When the <a href="#v">-v</a> flag is on, the scaling
factor used will be displayed during execution.<br>
<br>
<a name="iaa"></a>The <span style="font-weight: bold;">aa</span>
intent, Absolute Appearance, simply maps the Jab colors directly
from source to destination, clipping any out of gamut colors to
the closest match. This attempts to match the exact appearance of
colors as closely as possible, but may not exactly map the white
point of the source to the destination, depending on how different
the viewing conditions are.<br>
<br>
<a name="ir"></a>The <span style="font-weight: bold;">r</span>
intent is like Absolute Appearance mode, but maps the white point
from source to destination precisely, and otherwise maps the Jab
colors directly from source to destination, clipping any out of
gamut colors to the closest match. This is equivalent to the ICC <span
style="font-weight: bold;">Relative Colorimetric</span> intent.<br>
<br>
<a name="ila"></a>The <span style="font-weight: bold;">la</span>
intent, Luminance matched appearance, linearly compresses or
expands the the luminance axis to match the source to the
destination space, while not otherwise altering the gamut,
clipping any out of gamut colors to the closest match. This is
often useful for appearance based soft proofing.<br>
<br>
<a name="ip"></a>The <span style="font-weight: bold;">p</span>
intent, Perceptual, uses "knee" type 3 Dimensional compression to
make the source gamut fit within the destination gamut. As much as
possible, clipping is avoided, hues and the overall appearance is
maintained. The white point is mapped precisely from source to
destination.This is equivalent to the ICC <span
style="font-weight: bold;">Perceptual</span> intent.<br>
<br>
<a name="ipa"></a>The <span style="font-weight: bold;">pa</span>
intent, Perceptual Appearance uses "knee" type 3 Dimensional
compression to make the source gamut fit within the destination
gamut. As much as possible, clipping is avoided, hues and the
overall appearance is maintained. The white point is<span
style="font-weight: bold;"> not</span> mapped from source to
destination, allowing the apperance parameters to alter the
chromatic mapping.<br>
<br>
<a name="ims"></a>The <span style="font-weight: bold;">ms</span>
intent, Saturation, uses 3 Dimensional compression and <span
style="text-decoration: underline;">expansion</span> to try and
make the source gamut exactly match the destination gamut, and
also favours higher saturation over hue or lightness preservation.
The white point is mapped precisely from source to destination.<br>
<br>
<a name="is"></a>The <span style="font-weight: bold;"></span><span
style="font-weight: bold;">s</span> intent, Enhanced Saturation,
uses the same basic gamut mapping as <span style="font-weight:
bold;">ms</span>, Saturation, but increases saturation slightly
in highly saturated areas of the gamut. This is equivalent to the
ICC <span style="font-weight: bold;">Saturation</span> intent.
The white point is mapped precisely from source to destination.<br>
<br>
<a name="ial"></a>The <span style="font-weight: bold;">al</span>
intent, Absolute Appearance (Lab), is similar to intent <span
style="font-weight: bold;">a</span>, but L*a*b* colorspace is
used rather than CIECAM02 Jab appearance space. This often leads
to poor reproduction of blue and red hues, but can be useful as a
reference mapping.<br>
</div>
<br>
<a name="w"></a> The <b>-w</b> flag forces the white points to be
mapped from source to destination, irrespective of the intent
chosen. This is useful if absolute intent is being used, and the two
media white points should match, but don't quite due to measurement
error.<br>
The <b>-w</b> flag can optionally be followed by three numbers,
that specify a color that white should be mapped to. This will be in
the colorspace used during linking (typically Jab space, which has
similar characteristics to L*a*b* space). This options can be useful
in fine tuning paper emulation in absolute colorimetric mapping
mode.<br>
<br>
<a name="c"></a><a name="d"></a> The <b>-c</b> and <b>-d</b>
options allow specification of the viewing conditions for the source
and destination colorspaces respectively. The viewing condition
information is used to map the profile PCS (Profile Connection
Space, which us either XYZ or L*a*b*) color into appearance space
(CIECAM02), which is a better colorspace to do gamut mapping in. The
viewing conditions allow the conversion into appearance space to
take account of how color will be seen under particular viewing
conditions.<br>
Viewing conditions can be specified in two basic ways. One is to
select from the list of "pre canned", enumerated viewing conditions,
choosing one that is closest to the conditions that are appropriate
for the media type and situation. Alternatively, the viewing
conditions parameters can be specified in detail individually. If
both methods are used, them the chosen enumerated condition will be
used as a base, and its parameters will then be individually
overridden.<br>
<br>
<a name="t"></a> The <b>-t</b> <i>tlimit</i> parameter sets the
total ink limit (TAC, Total Area Coverage) for a CMYK source
profile, as a total percentage from 0% to 400%. This affects the
gamut assumed for the source profile. By default, a total ink limit
will be estimated from the source profile B2A table.<br>
<br>
<a name="T"></a> The <b>-T</b> <i>klimit</i> parameter sets the
black channel ink limit for a CMYK source profile, as a total
percentage from 0% to 100%. This affects the gamut assumed for the
source profile. By default, a black ink limit will be estimated from
the source profile B2A table.<br>
<br>
<br>
<u> <a name="GG"></a>Inverse outprofile A2B Options:</u><br>
<br>
When the <b>-G</b> flag is used, the A2B table is inverted "on the
fly", allowing various additional choices as to what device values
are used to reproduce a particular color. (If the <b>-G</b> flag is
not used, then such decisions are encoded in the B2A table in the
profile, and cannot be altered during linking).<br>
<br>
<a name="k"></a> -<b>k</b> parameter sets the target level of black
(K) when creating a B2A CMYK output tables. This is often called a
black level, a black inking rule, black generation, or under color
removal. These set the target black level:<br>
<br>
<b> -kz</b> selects minimum black (0.0)<br>
<b> -kh</b> selects a black level value of 0.5<br>
<b> -kx</b> selects the maximum possible black (1.0)<br>
<b> -kr</b> selects a linear level ramp, starting at minimum black
for highlight, and maximum black for shadow (equivalent to -kp 0 0 1
1 1). This is the default.<br>
<b>-kt</b>, will preserve the black amount from the source (CMYK)
profile to the destination (CMYK) profile as much as possible.
This may be most useful in creating a CMYK to CMYK conversion
between two different press conditions, while preserving as much as
possible the black only use for text etc. in anything
converted. Note that if the source black point is darker than the
destination, composite black will still be generated for K only
input. The <span style="font-weight: bold;">-fk</span> option can
be used to avoid this behavior.<br>
<b>-ke</b>, will preserve the black amount from the destination
profile B2A table (CMYK).<br>
<br>
<b><a name="kp"></a>-k p stle stpo enpo enle shape</b> allows
an arbitrary black locus ramp to be defined, consisting of a
starting value (stle) for highlights, a breakpoint L value (stpo)
where it starts to transition to the shadow level, an end breakpoint
L (enpo) where it flattens out again, and the finishing black level
(enle) for the shadows. There is also a curve parameter, that
modifies the transition from stle to enle to either be concave
(ie. the transition starts gradually and and finished more
abruptly) using values 0.0-1.0, with 0.0 being most concave, or
convex (the transition starts more abruptly but finishes gradually),
using values 1.0-2.0, with 2.0 being the most convex.<br>
<br>
Typical black value generation curve with parameters something like:
-kp 0 .1 .9 1 .5<br>
<br>
<tt> 1.0 K |
enpo<br>
|
_______ enle<br>
|
/<br>
|
/<br>
|
/<br>
|
/<br>
stle | ------/<br>
+-------------------<br>
0.0 K
0.0
stpo 1.0<br>
White
Black<br>
<br>
</tt>For minimum sensitivity of printed output to the lighting
spectrum, it currently seems best to use the maximum possible black,
but other black generation levels (ie. 0.3 to 0.5) may well be
preferred if one wants to minimize the noisy appearance of black on
an inkjet device, or if the banding behaviour or other rendering
flaws of the printer is to be minimized. <br>
<br>
Note that the black level curve is applied throughout the gamut,
resulting in GCR (Grey Component Replacement). There is no facility
to restrict black to just neutral colors, hence UCR is not currently
supported.<br>
<br>
<b><a name="kq"></a>-k q stle0 stpo0 enpo0 enle0 shape0 stle2 stpo2
enpo2 enle2 shape2</b> is a combination of the <b>-kt</b> and <b>-kp</b>
functionality, with the black being preserved in CMYK to CMYK
linking, with the output black constrained to be between the first
and second set of curve parameters.<br>
<br>
The <a href="xicclu.html">xicclu</a> tool can be used to plot out
the resulting black level for a given set of parameters, by using
the <a href="xicclu.html#g">-g</a> flag of a profile already
created from the same .ti3 file.<br>
<br>
<a name="K"></a> <span style="font-weight: bold;">-K parameters.</span>
Any of the <span style="font-weight: bold;">-k</span> options above
can use the <span style="font-weight: bold;">-K</span> version, in
which rather than a black value target being defined by the inking
rule, a black <span style="text-decoration: underline;">locus</span>
target is defined. For each lookup, the minimum possible black level
and the maximum possible black level is determined, the former
corresponding to a locus target value of 0, and the latter
corresponding to a locus target value of 1. For instance, at the
white point, no black will be used in the output, even if the black
locus specifies a maximum (since the maximum amount of black that
can be used to print white is actually zero). Similarly, at the
black point, black may well be used, even if the black locus
specifies zero black (since a certain amount of black is needed to
achieve the desired density of color). <br>
<tt> </tt><br>
<a name="l"></a> The <b>-l</b> <i>tlimit</i> parameter sets the
total ink limit (TAC, Total Area Coverage) for the CMYK separation,
as a total percentage from 0% to 400%. This affects the gamut
assumed for the destination profile, as well as the ink limit in the
generated device link. The limit value should generally be set a
little below the value used in the test chart generation, to avoid
the very edges of the gamut. If the test chart ink limit has been
chosen to be a little beyond an acceptable level, then this number
should be the acceptable level. Although limits can be set below
200%, this will generally restrict the color gamut noticeably, as
fully saturated secondary colors will not be reproduced. Values are
between 220% and 300% for typical printing devices. By default, a
total ink limit will be estimated from the destination profile B2A
table. The ink limit will be in final calibrated device values if
the profile includes calibration information.<br>
<br>
<a name="L"></a> The <b>-L</b> <i>klimit</i> parameter sets the
black channel ink limit for the CMYK separation, as a total
percentage from 0% to 100%. This affects the gamut assumed for the
source profile, as well as the ink limit in the generated device
link. For printing press like devices, this can be used to prevent
the black channel screening pattern "filling in". Typical values
might be from 95% to 99%. By default, a black ink limit will be
estimated from the source profile B2A table. The ink limit will be
in final calibrated device values if the profile includes
calibration information.<br>
<br>
<b><a name="P"></a></b>The <b>-P</b> option causes a diagnostic 3D
<a href="File_Formats.html#VRML">VRML</a> plots to be created that
illustrate the gamut mapping generated.<br>
<br>
<a name="p1"></a>The <i><b>inprofile</b></i> argument specifies the
source profile. This is the color space/device we are attempting to
emulate in the overall conversion. A <small>TIFF or JPEG file with
embedded profile may be used here.</small><br>
<br>
<a name="p2"></a>The<i><b> outprofile</b></i> argument specifies the
destination profile. This is the device we are actually displaying
on or printing to. A <small>TIFF or JPEG file with embedded profile
may be used here.</small><br>
<br>
<a name="p3"></a>The <i><b>linkedprofile</b></i> argument specifies
the resulting device link profile. This profile will contain the
color transform from the source space to destination space.<br>
<br>
For information on typical usage, see the <a href="Scenarios.html">Typical
Usage Scenarios</a> page.<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
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