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List:       koffice
Subject:    Re: pantone color
From:       Thomas Zander <zander () planescape ! com>
Date:       2002-05-02 15:10:07
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On Thu, May 02, 2002 at 09:44:06AM +0200, Thomas Diehl wrote:
> Am Dienstag, 30. April 2002 23:29 schrieb Patrick Julien:
> 
> > I'm not sure what the requirements for "full process color functional"
> > would be...
> >
> > Does this mean different color models like CMYK and support for it's
> > various channels?
> 
> Process colors means mostly CMYK support, ie 4 color channels. (This is 
> really not just a "Pantone" thing, BTW. The subject is misleading.)

Right.

> >  I
> > think this kind of testing would set me back quite a bit in terms of
> > paper and ink :)
> 
> Actually, CMYK is usually not printed in color but in grayscale on the user 
> level (since everything is just about "dot patterns", not actual colors 
> here). The colors are coming in much later, during the offset printing 
> process (ie in a real printery). 
> 
> The purpose of CMYK is the ability to easily get colors separated in a way 
> that is usable for professional (offset) printing. The conversion to the 
> CMYK color model (from RGB or palette colors) and the following separation 
> process makes it possible to bring the zillions of colors in a given 
> picture down to just Cyan, Magenta, Yellow, and Black raster screens at 
> different angles. (These "raster screens" are the way how the printing dots 
> are distributed over the page. The separated C, M, Y, and K dots have to be 
> printed in certain patterns next to each other. And the different angles 
> help to avoid printing those dots just on top of each other.)
> 
> Therefore, at production stage, there is no need for color. Everything is 
> about dots, their distribution, line screens and angles. It only becomes a 
> color picture afterwards, when everything is being run through an (offset) 
> printing machine and the complete picture gets restored from the formerly 
> separated CMYK elements (ie from the 4 different dot patterns that were 
> created during color separation).
> 
> I'd recommend having a look at a description of the (offset) printing 
> process to get an idea of what this is about and what would be necessary 
> from the application side. It might also help to have a look at what eg 
> PhotoPaint is doing (although the code is unfortunately not accessible).
> 

I have to disagree here; the photo editing application knows just about the 
CMYK colors and converting them to and from RGB.
The steps you describe are done later in the process.

Here is a short summery;
* splitting the CMYK into seperate channels; either the paint program, or the
print software. but that is a breeze since its just simple data manipulation.
* The dots and their distribution as you say. This is the screening process
and is printer dependent. This is done by a RIP or another special machine.

Bottom line; Krita should know about 4 channel images and should be able to 
convert to and from RGB. 

Optional are ICC profiles for color management.  The basis of this is simple, 
the implications of using ICC profiles is huge. And wonderful :) 

-- 
Thomas Zander                                            zander@earthling.net
The only thing worse than failure is the fear of trying something new

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