Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 exptools 1/6/84; site ihnet.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!houxm!ihnp4!ihnet!tjr From: tjr@ihnet.UUCP (Tom Roberts) Newsgroups: net.physics Subject: colors Message-ID: <152@ihnet.UUCP> Date: Mon, 20-Aug-84 10:35:33 EDT Article-I.D.: ihnet.152 Posted: Mon Aug 20 10:35:33 1984 Date-Received: Tue, 21-Aug-84 00:16:37 EDT Organization: AT&T Bell Labs, Naperville, IL Lines: 21 I am puzzled by the recent discussions of color vision, and the following: A few years ago I attended a lecture/demonstration by Dr Land, inventor of the Polaroid camera. During this demonstration he displayed two (monochrome) slide photographs of the same image, one taken with a red (I think) filter, one with a green (I think) filter. He displayed the two images side-by-side, using red and white projectors. When he caused the two images to EXACTLY superimpose, a FULL COLOR image appeared (suddenly!). I find this striking demonstration hard to understand using a theory that color vision is strictly frequency dependent - I have not made any effort to do so (e.g. measuring the frequency spectrum of his white projector). Superficially, it seems as though some sort of intereference effect is being interpreted by the eye as "color" (though both projectors were incoherent incandescent sources). Does anyone know what is really going on? Tom Roberts ihnp4!ihnet!tjr