[NTG-context] Issues with RGB to CMYK conversion with color profiles (was: Colormanagement)

Jan U. Hasecke juh+ntg-context at mailbox.org
Mon Nov 12 09:02:15 CET 2018


Hi all,

with the following file I tested the color conversion of context.

I get the same CMYK-values in the output pdf file using different color
profiles. A friend of mine can test the color values of PDF with a
special software.

My guess: the profiles are not used during pdf generation.
You can test this by commenting/uncommenting the other profile.

I created the files with

context --mode=print example.tex

My context version is
mtx-context     | ConTeXt Process Management 1.02
mtx-context     | current version: 2018.08.30 18:41


Is this the correct way of producing cmyk-pdfs?

I am missing the declaration of the RGB color profile. When doing color
management in Scribus I define two profiles: one for RGB and one for
CMYK. AFAIK you need both to convert rgb to cmyk.

Any hints?
juh

--- example.tex ---

\definecolor  [hs-logoblau]   [r=0.000, g=0.314, b=0.580]
\definecolor  [hs-dunkelblau] [r=0.258, g=0.474, b=0.737]
\definecolor  [hs-hellblau]   [r=0.6, g=0.737, b=0.858]
\definecolor  [hs-orange]     [r=0.866, g=0.286, b=0.003]

\startnotmode[print]
\setupcolors[cmyk=no,rgb=yes]
\stopnotmode

\startmode[print]
\setupcolors[cmyk=yes,rgb=no]
\setupbackend[
	format=PDF/X-1a:2003,
%   intent={ISO Coated v2 300\letterpercent\space (ECI)},
   intent={SWOP2006_Coated3v2.icc},
   ]
\stopmode

\setuppapersize [A4] [A4]

\starttext



\blackrule[width=3cm,height=1cm,depth=0pt,color=hs-orange] HS Orange
r=0.866, g=0.286, b=0.003
\blank

\blackrule[width=3cm,height=1cm,depth=0pt,color=hs-logoblau] HS Logoblau
r=0.000, g=0.314, b=0.580
\blank

\blackrule[width=3cm,height=1cm,depth=0pt,color=hs-dunkelblau] HS
Dunkelblau r=0.258, g=0.474, b=0.737
\blank

\blackrule[width=3cm,height=1cm,depth=0pt,color=hs-hellblau] HS Hellblau
r=0.6, g=0.737, b=0.858


\stoptext



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