how to convert RGB into CMYK?
wang
I'd like to convert RGB color into CMYK color but don't know how to
calculate. In Adobe Photoshop RGB tif file can be converted into C, M,
Y, and K component. I'm content with the result, but don't know what
the calculation rule is. Many thanks for your help in advance!
K.W.Wang
Jeffrey H. Coffield
In Postscript you can set a color using setrgbcolor and then read it
back using currentcmykcolor.
The formulas used are in section 7.2.3 of the PostScript Language
Reference Manual.
Beware that this is a very simplistic approach as accurate conversion
requires knowledge of the actual colors the RGB values represent as
compared to the actual calibrated ink colors that a CMYK printer uses.
Jeff Coffield
toby
That's right. The methods Photoshop uses are highly non-linear and
carefully tuned for various printing methods - offset lithography is
most common. Significantly different colour gamuts and device colour
spaces (at both ends) must be supported. There are also several
parameters which affect the separation, including press dot gain and
distinct approaches to generating the black plate. As a historical
oddity, preferred practices can even be quite different in different
continents!
You may find this code helpful: http://www.littlecms.com/
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> Jeff Coffield