Path: utzoo!mnetor!uunet!husc6!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!mit-amt!turk
From: turk@mit-amt.MEDIA.MIT.EDU (Matthew Turk)
Newsgroups: comp.graphics
Subject: Re: Naive Question About Primary Colors
Message-ID: <2186@mit-amt.MEDIA.MIT.EDU>
Date: 25 Mar 88 23:30:17 GMT
References: <7871@oberon.USC.EDU> <7779@apple.Apple.Com>
Distribution: na
Organization: MIT Media Lab, Cambridge, MA
Lines: 14
Keywords: Yellow versus Green
Summary: Not quite *any* three...

In article <7779@apple.Apple.Com>, grady@Apple.COM (Grady Ward) writes:
> 
> ...  Any set of three colors can be "primary" for non-
> color blind humans, because, like a TV set, we have three sensing
> rod varieties.
> 

Well, almost.  The three colors must be "perceptually independent",
i.e. no mixture of two of them can make the third.  Also, in additive
color the choice of the three primaries limits the gamut of colors
that can be represented (to the inclusive triangle in the CIE 
chromaticity diagram).  

	Matthew