Re: Digital Negs - RGB vs CMYK

From: Katharine Thayer ^lt;>
Date: 12/02/04-06:55:37 AM Z
Message-id: <>

Kate M wrote:
> When printing gum, you use the R negative to print with a cyan pigment,
> the G negative to print magenta, and the Y negative to print with blue
> pigment. So the IMAGE is CMY (unless you want to alter the pigments of
> course). The main debate between RGB and CMYK is that a lot of the
> density with CMYK is carried on the K channel, therefore (some say, and
> I would tend to agree), you must print with a K pigment to get good
> density, and this interferes wiyth the other pigments in some areas of
> the print.

This is very nicely put, Kate, and in a lot fewer words than I have
expended on the subject. I would just add that my criticism of the
default CMYK isn't only that much of the density is moved from the color
channels to the K channel, but that the color information is altered
differentially; typically the cyan is closer to the true cyan than the
magenta and yellow are to their true CMY values. This differential
alteration of the color values is done to accommodate the requirements
and limitations of process inks, which our pigments do not share. So it
seems to me that with default CMYK you're starting out with a distorted
color balance in the separations that you would have to work against to
get a good color balance in the print. This is not to say I think it
can't, or shouldn't be attempted; I think with practice you can become
adept at printing good color balance from about anything (there are
people who print almost photo-realistic color from a single negative,
after all).
Received on Thu Dec 2 14:51:48 2004

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