On Oct 4, 2011, at 8:34 PM, john Culleton wrote:
Imagemagick will convert a bitmap file from RGB to CMYK color space. So will Scribus (with the help of an icc profile of course.) So I can reverse the process and take the CMYK factors, key them into a color mapping part of Scribus or Gimp, and jot down the RGB equivalent. The resulting palette will be an RGB palette that is within the CMYK gamut.
I just want to avoid all that labor.
I'm not sure about Imagemagick, but the key here is that with Scribus one has to use a specific icc color profile to get a specific instance of a CMYK-type colorspace.
You can also do the same thing straight within Inkscape.
Also, you need to specify *which* RGB colorspace you want to deal with. Input data in sRGB and you'll get different CMYK values than if you specify input data in Adobe RGB or Wide RGB.
So you probably want sRGB, and not just any RGB. Or maybe you have a use case where you need a different RGB.
Have you tried just using a CMYK profile in Inkscape (such as "U.S. Web Coated (SWOP) v2", "ISO Coated v2 300% (ECI)", "Coated FOGRA27 (ISO 12647-2:2004)", "Japan Color 2002 Newspaper" or some other), and then using the color picker there?
Or if you just want to work to make an image targeting a specific CMYK, just have that specific icc profile selected and then the color picker will automatically warn you when you go out of gamut, the display system can give you adjusted previews, and you'll get correct CMYK values stored in the SVG file in a standards compliant way that includes sRGB fallbacks.