Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!burl!codas!mtune!whuts!davel From: davel@whuts.UUCP Newsgroups: sci.misc Subject: Re: Color Message-ID: <3375@whuts.UUCP> Date: Thu, 3-Dec-87 10:52:14 EST Article-I.D.: whuts.3375 Posted: Thu Dec 3 10:52:14 1987 Date-Received: Sun, 6-Dec-87 21:31:34 EST References: <162300002@uiucdcsb> Organization: AT&T Bell Laboratories Lines: 29 In article <162300002@uiucdcsb>, kadie@uiucdcsb.cs.uiuc.edu writes: > 1) On TV's and computers screens, why is it RGB (red, green, blue) > instead of RYB (red, yellow, blue) the primary colors? Green, not yellow, is the primary color. The three types of cones in our eyes have peak sensitivities to red, green, and blue. Red+green "add" to appear "yellow", because yellow light stimulates both green and red cones much more than blue cones. When you mix paints, you are using "subtraction", which is more complicated. Yellow paint absorbs blue light well, green and red less well. Blue paint absorbs red and yellow well, green and violet less well. When you mix the paints, you get therefore get a paint which absorbs red very well, yellow fairly well, blue fairly well, but green only somewhat, so it appears green. > > 2) Some light wave length produces the color green. A mixture of > the wave lengths of blue and yellow also produces green. Not true (see above). Recasting the question, substituting "yellow" for "green"... > Even though these two greens are indistinguishable to our eyes, are there > (could there be) instruments that distinguish them? Yes. Absolutely. They exist. -- David Loewenstern Bangpath: {rutgers...}!moss!whuts!davel The above are not my opinions. My lawyer has advised me not to tell you what my opinions really are.