Press Proof Metamerism
Press Proof Metamerism
- Subject: Press Proof Metamerism
- From: Rick Gordon <email@hidden>
- Date: Thu, 11 Sep 2003 10:15:32 -0700
We just got some wet proofs of some test pages for a book that is to be printed in China (C&C Printing). We have generated a color-managed workflow between my Artisan monitor and custom profiles of their wet proofs on our chosen paper. Results look spot on.
But one issue that I am noticing is that the book contains 300 some-odd grayscale graphics, which I am separating to CMYK from Photoshop quadtone files, to give a very subtly toned effect. I'my generating these separations using a profile generated form the same data as the others with heavy black generation. (Using ProfileMaker Pro, the settings are G4 black generation starting at 0% and going to 95%, 360% TIL as requested).
The printed images match perfectly when view under 5000K light (having a cool-toned effect with the blue component exceeding the magenta), but when viewed under tungsten or halogen light, the images look more red-purple toned (more like a selenium print, but just a little too purplish for my taste). The Lab values and CMYK values in the file reflect my intent, but I am surprised by the strong metameric aspect, having thought that that was less prevalent with press inks. (And it is not apparent to a noteworthy level in the color images.)
So, are there any considerations about how I might generate the separation to minimize this effect, outside of just giving up some level of toning by blending an untoned, CMYK-separated copy with the other to back off the amount of toning.
By the way, I'm talking about small toning Lab numbers (as shown in the info palette with the same separation profile set as the CMYK working space) with the a channel varying between 1 and -1 and the b channel varying between 0 and -4 (mostly -1 to -3).
(With your indulgence, I am submitting this both the the ColorSync and Color Theory lists, since any change in procedure will be needed to be effected very quickly.)
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RICK GORDON
EMERALD VALLEY GRAPHICS AND CONSULTING
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WWW:
http://www.shelterpub.com
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