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From: hutch@sdcsvax.UUCP
Newsgroups: comp.graphics
Subject: Re: Color questions
Message-ID: <3283@sdcsvax.UCSD.EDU>
Date: Sun, 7-Jun-87 02:00:24 EDT
Article-I.D.: sdcsvax.3283
Posted: Sun Jun  7 02:00:24 1987
Date-Received: Sun, 7-Jun-87 18:46:30 EDT
References: <20537@sun.uucp>
Reply-To: hutch@sdcsvax.UCSD.EDU (Jim Hutchison)
Distribution: comp
Organization: UCSD EMU Project (Educational Microcomputer Unix)
Lines: 29

In article <20537@sun.uucp> falk@sun.uucp (Ed Falk) writes:
>Here's a related question, does anybody know the conversion factors to
>map colors in Red-Green-Blue space to Cyan-Yellow-Magenta-Black?  What
>I would like to do is generate four images on a high-res laser printer
>that can be used directly for printing; i.e. do the seperation in
>software.

RGBA --> CYMB seems a pretty natural thing.  Am I wrong?

Is it as simple as:

    R/2 --> YM   G/2 --> CY   B/2 --> CM   A --> B	???

The human eye is supposedly happy with 100dpi (not printers, just humans :-),
whether this is true or not this leads to another question.

At what dpi does one switch from ordered dithers to halftone dithers?  With
certain varieties of plotters (thermals all) the number of pixels turned on
does not have a linear effect on the amount of ink/crayon smeared on the media.
Halftone tone dithers can be arranged so that the balls are of the proper size
to deal with making hot-charged/cool-synced spots of appropriate sizes.

Any thoughts?

-- 
    Jim Hutchison   		UUCP:	{dcdwest,ucbvax}!sdcsvax!hutch
		    		ARPA:	Hutch@sdcsvax.ucsd.edu
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