From: Henning Hraban Ramm <hraban@fiee.net>
To: mailing ConTeXt users list for <ntg-context@ntg.nl>
Subject: definition and separation of colors
Date: Tue, 16 Nov 2010 21:37:50 +0100 [thread overview]
Message-ID: <6B3E8A9C-2016-4483-83AF-D3BAB999139A@fiee.net> (raw)
I stumpled upon a ambiguous color definition in my automatically
generated documents:
\definecolor[Custom][c=0,m=1,y=0,k=0,r=0,g=0,b=0,]
I.e. the color is defined in CMYK mode as 100% magenta and in RGB as
0/0/0 black.
In the PDF the color is shown as black, according to Acrobat's
preflight defined as RGB 0/0/0; CMYK separation depends on the
profile, e.g.:
Generic CMYK: 76/71/65/81
ISO Coated FOGRA27: 86/85/79/100
Euroscale Coated: 95/83/82/90
(I didn't expect the Euroscale Coated profiles to differ that much!)
If I say \setupcolors[rgb=no], I get CMYK 100/100/100/0.
This is not a good separation algorithm - GCR or UCR would be nice,
but at least RGB 0/0/0 should render as CMYK 0/0/0/100.
(Perhaps you could include something like littleCMS in LuaTeX and even
deal with images?)
It doesn't change if I define in different order, like
\definecolor[Custom][r=0,g=0,b=0,c=0,m=1,y=0,k=0,]
I get magenta only if I leave out the RGB values.
It seems that in ConTeXt the RGB definition always takes precedence?
Is this intended?
Greetlings from Lake Constance!
Hraban
---
http://www.fiee.net/texnique/
http://wiki.contextgarden.net
https://www.cacert.org (I'm an assurer)
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next reply other threads:[~2010-11-16 20:37 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-16 20:37 Henning Hraban Ramm [this message]
2010-11-17 0:11 ` Hans Hagen
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