[texhax] CMYK color v. RGB

[Pierre MacKay]

Postscript is exactly where such conversions between color mappings take 
place. 

Complete graphics packages like Illustrator come with elaborate filters 
to make the conversions. 

It is a great pity that Illustrator cannot be run under Unix directly, 
but with qemu it can be run in a
qemu Windows window. 

RGB was designed for display screens, and works on an entirely different 
color model from
CMYK.  One of the good things about Illustrator is that it gives you the 
CMYK values for
Pantone inks, which can be used in epsf specials. Here for instance is 
the code
to produce PANTONE 179 U taken from a plain TeX file.  The advantage of this
is that it uses the PANTONE CMYK values for the inks.  The color on the 
display, or
on an Inkjet or Laser printer may not be quite the same, but it doesn't 
matter.  The
PANTONE color is going to be pretty standard all across the printing 
industry.

\ORNtext={\special{ ps:gsave [/Separation (PANTONE 179 U)
[/DeviceCMYK] {dup 0.0 mul exch dup 0.79 mul exch dup 1 mul exch
0.0 mul}]setcolorspace}\box1\special {ps:grestore}}

All that to write \box1 in red-orange, rather than black.

I use an HP inkjet for color proofs, and my understanding is that the HP 
printer
drivers do CMYK -> RGB conversions even though the ink cartridges would
seem to be more appropriate for CMYK, by the very fact that they are ink 
cartridges.

Pierre MacKay