1999.12.08 16:27 "Re: Testing: [was: Test Adobe ZIP TIFF needed]", by Tom Lane
People keep bringing up the addition of CMYK support on Slashdot, and are always shot down with "Yeah, but we'd need to license patents to do that!!!!" (I don't believe there would be any patents involved in simple CMYK<->RGB conversion.)
You could do it without any patents, probably, but trade secrets might be as big or bigger an obstacle. Adobe doesn't publish the details of the CMYK separation methods used in Photoshop, for example. AFAIK none of the big prepress players likes to talk about how they do it.
You can do quick-and-dirty conversion pretty easily (eg, C=1-R etc, K=min(C,M,Y)) but achieving pleasing results is a whole 'nother ball game. And since the only people who actually use CMYK are in the prepress business, a half-baked implementation is just about useless.
regards, tom lane