On 9/16/10, Jonatã Bolzanwrote:
But the *HUGE* problem is that there is no such thing as "the CMYK colorsystem". If a print shop is going to produce the same color from one week to the next, they need to be working in a *specific* CMYK colorspace.
I based my understanding of this issue in ImageMagick documentation: http://www.imagemagick.org/Usage/formats/
"RGB and CMYK are not colorspaces, they are color systems (which IM controls using the "-colorspace" operator). There is no single RGB or CMYK colorspace, but a literally infinite amount of different colorspaces are possible in each color system."
Looks like you are on a terminology dispute :) There are color models (same as systems) such as RGB, CMYK, CIE XYZ, Munsell and so on. They are single. And then there are color spaces whose amount is truely infinite. So there's nothing to argue about. You guys just put different meaning into the word "system" :)
Get my point: I set in Inkscape the fill of a shape with C0 M50 Y100 K0 that is orange. I need in the C off-set platewith no cyan ink, M off-set plate with 50% of magenta ink, Y off-set plate with 100% of yellow ink and K off-set plate with no black ink. If I save it in a PDF in RGB, I'll need a ICC profile to convert these values to CMYK. But doing this will never give me the real values I want (C0 M50 Y100 K0). They will always convert the colors based on the profile conversion. What can I do? That is what I want to say, the ICC profile is not a must to have an output in CMYK because some people (like me) just want the exact values used in the draw.
Yes, there are cases when RGB to CMYK conversion should be color unmanaged. For this very reason such optional functionality was added to CMYKTool in one of the recent versions.
Alexandre Prokoudine http://libregraphicsworld.org