On 2/4/07, Hans Hagen
Peter Rolf wrote:
But to my surprise ConTeXt automatically converts my RGB colors (even the MP defined ones), except that the final colors are in the CMY instead of CMYK color space. All I want is a true RGBtoCMYK conversion. I know about the calculating limitations in TeX, so I can wait for an implemetation of that macro in LuaTeX.
but even then ... we need a formula ...
Most pages on the internet list the following simple conversion formula: C' = 1 - (R/range) C = (C' - K') / (1 - K') M' = 1 - (G/range) M = (M' - K') / (1 - K') Y' = 1 - (B/range) Y = (Y' - K') / (1 - K') K' = MIN(C',Y',M') K = K' In the special case of K'=1, use (0,0,0,1) (I'm not a TeX guru, but I assume that conversion with current macros should not be much more difficult than conversion with luaTeX.) Mojca