DEC colours

From: Paul Koning <pkoning_at_equallogic.com>
Date: Tue Nov 16 09:05:28 2004

>>>>> "John" == John Allain <allain_at_panix.com> writes:

 John> Why I like RGB, chapter 3... All of electronic graphics is
 John> based on it. If it looks good on a TV, a computer monitor or
 John> anything from a Digicam, then it has been RGB digitized at some
 John> point. A digital camera just seems like a super convenient
 John> instantaneous color digitizer. You don't mix pigments from Red
 John> Green and Blue but the result of any pigment mix color can be
 John> communicated with RGB very well.

No, it can't.

There are colors that can be expressed in CMYK (four color "process"
printing) that cannot be expressed in RGB. There are colors that can
be made up in pigments that cannot be expressed in either.

People who do this stuff for a living talk of "gamut" -- the range of
colors that a particular system can describe. The RGB gamut and the
CMYK gamut largely overlap, but each has a range outside that of the
other. And there are other schemes (like Lab) that have yet a
different gamut. For that matter, there are printer with more than
four colors -- that is done to get a larger gamut.

You can read about this stuff in the Adobe Photoshop manual, or in
Electronic Publishing magazine, or in any decent textbook on color
printing. If you want to do professional grade color, you have to go
way beyond the narrow confines of thinking about color as simply RGB
color.

       paul
Received on Tue Nov 16 2004 - 09:05:28 GMT