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List:       koffice-devel
Subject:    Re: Color separation ?
From:       m_elter () t-online ! de (Matthias Elter)
Date:       2000-12-27 9:39:36
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On Wednesday 27 December 2000 05:32, John Califf wrote:
> On Tuesday 26 December 2000 09:46 am, Lenny wrote:
> > Merry kmas to you all,
> >
> > does anyone know more about patent issues concerning color separation ?
> > I think it's about Pantone (tm) and CMYK, but i cant find anything.
> > Does this affect Krayon, KIllu and if how ?
> > --
> > ~lenny();
>
> I didn't know there is a patent problem.  Krayon does have some CMYK code
> already in it (to translate back and forth between other color modes and
> adjust channels, etc), and will have a floating dialog for CMYK.

There are no patent problems with CMYK but with some color management systems.

> I don't see how anyone can patent a color system which is basically so
> simple.  Check the krayon module in koffice.
> koffice/kimageshop/core/kis_color.cc and kis_color.h.  It all claims to be
> GPL.

Yes, this is GPL code written by me. The problem is there is no algorithm to 
translate RGB<->CMYK without losing information. The real conversion is 
complicated, not so much mathematically, but because there are so many 
factors involved. You need to know the type of paper you're printing to, the 
types of ink you're printing with, and to really do it properly, you need to 
calibrate your monitor and printer. Photoshop does this with conversion 
tables.

All you ever might want to know about color can be found here:

http://www.inforamp.net/~poynton/Poynton-color.html

Other usefull links:

http://www.faqs.org/faqs/graphics/
http://www.landfield.com/faqs/graphics/algorithms-faq/
http://www.geocities.com/~charlie_x/gfxlinks.htm

Bye,
Matthias

-- 
Matthias Elter
elter@kde.org
me@caldera.de
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