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From: jon@eps2.UUCP
Newsgroups: sci.physics,comp.graphics,comp.sys.ibm.pc
Subject: Re: Color questions
Message-ID: <93@eps2.UUCP>
Date: Tue, 2-Jun-87 08:52:15 EDT
Article-I.D.: eps2.93
Posted: Tue Jun  2 08:52:15 1987
Date-Received: Thu, 4-Jun-87 06:17:30 EDT
References: <1937@druhi.ATT.COM> <725@bsu-cs.UUCP> <6861@mimsy.UUCP>
Distribution: comp
Organization: Scumtronics Inc.
Lines: 26
Xref: utgpu sci.physics:1469 comp.graphics:668 comp.sys.ibm.pc:3979
Summary: CMYK = cyan magenta yellow black

In article <6861@mimsy.UUCP>, chris@mimsy.UUCP (Chris Torek) writes:
> In article <725@bsu-cs.UUCP> dhesi@bsu-cs.UUCP (Rahul Dhesi) writes:
> >... Your typical printer will tell you he or she uses only three
> >colors, with a little black thrown in.
> Actually, high quality color magazine printing usually uses four
> colours plus black.

No, Rahul is correct.  What you see in magazines usually begins as
continuous tone art (photographs or transparencies) and are then
scanned with a Hell or Crosfield laser scanner to produce four
color separations (cyan, magenta, yellow and black) which look like
pieces of black and white transparency film with halftone dots on
them.  A printer can then etch printing plates from these color seps.
For the past year I have been sending images back and forth from our
workstations to Scitex and Hell pre-press equipment at various color
separation houses in the Bay Area and making Cromalins (proofs) so
I've got some idea of what's going on here.

In printing packages they often use a different technique.  They use
the color of ink that is actually getting printed, rather they simulate
continuous tone with CMYK halftone dots.  I'm looking at a "Bounce"
fabric softener box and it looks like they used blue, red, and yellow
ink to produce a white, yellow, orange and blue package.


Jonathan Hue	DuPont Design Technologies/Via Visuals		leadsv!eps2!jon