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From: stekas@hou2g.UUCP (J.STEKAS)
Newsgroups: net.physics
Subject: Re: colors
Message-ID: <303@hou2g.UUCP>
Date: Mon, 20-Aug-84 14:28:58 EDT
Article-I.D.: hou2g.303
Posted: Mon Aug 20 14:28:58 1984
Date-Received: Tue, 21-Aug-84 00:24:57 EDT
References: <152@ihnet.UUCP>
Organization: AT&T Bell Labs, Holmdel NJ
Lines: 18

Colors:

Land had a very nice Scientific American article a few years back.
In it, he explained the how color perception REALLY worked, as op-
posed to how people thought it worked.

What he found was that color is not absolute but relative.  The color
we perceive an object to be has nothing to do with the absolute spectrum
of light reflected from it, but of the difference between its reflected
spectrum and those of other objects in the field of view.  The effect is
to subtract out the effect of the spectrum of illuminating light.

That's why a peice of white paper looks just the same to our eye whether
illuminated by incadescent (red), sunlight (white), or flourescent (blue)
light.  Color film records the abolute spectrum, so the proper combinations
of films and filters are needed for different lightings.

Jim