Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83 based; site hou2g.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!houxm!hou2g!stekas 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