Xref: utzoo sci.electronics:3882 rec.audio:8418 Path: utzoo!attcan!uunet!cbmvax!vu-vlsi!dsinc!syd From: syd@dsinc.UUCP (Syd Weinstein) Newsgroups: sci.electronics,rec.audio Subject: Re: Looking for Blue LEDs Keywords: blue blue blue, not yellow or red or green Message-ID: <441@dsinc.UUCP> Date: 23 Sep 88 15:00:06 GMT References: <1138@nmtsun.nmt.edu> <862@ritcv.UUCP> <255@rna.UUCP> <4422@lynx.UUCP> <871@ritcv.UUCP> Reply-To: syd@dsinc.UUCP (Syd Weinstein) Followup-To: sci.electronics Organization: Datacomp Systems, Inc., Huntingdon Valley, PA 19006 Lines: 43 In article <871@ritcv.UUCP> cep4478@ritcv.UUCP (Christopher E. Piggott) writes: >Question: why are R.G.B. monitors Red, GREEN, blue, when GREEN is not one of >the primary colors (being a combination of blue and yellow)? Why shouldn't >it be red, YELLOW, blue? Its time to explain the color wheel again. The Primary colors are different depending on whether you are talking about light adding up to make colors, or pigments subtracting to make colors. The three primary additive colors are Red, Green and Blue (suprize, RGB monitors) The three subtractive colors are Cyan (a blue-ish green), Magenta (A Red with some purple like tint) and Yellow. In school you learned to mix yellow and blue crayons to make green, the actual primary pigment subtraction (or filtration) is yellow and cyan to make green. If fact, each combination of two of one set of primaries makes one of the other. We call that the color wheel, and if my memory serves me correctly: Red Yellow Magenta Green Blue Cyan Ok, each color is the opposite of the one diagonally across (ie red and cyan, green and magenta, yellow and blue), and each color is made of the two ajacent to it (read and green light makes yellow, magenta and cyan pigment filter white to make blue) How it works subtractively is that Cyan does not let Red through, Magenta does not let Green through and Yellow does not let Blue through thus take white light and filter out the Red and Green and you have blue left. Totally confused? -- ===================================================================== Sydney S. Weinstein, CDP, CCP Datacomp Systems, Inc. Voice: (215) 947-9900 {allegra,bellcore,bpa,vu-vlsi}!dsinc!syd FAX: (215) 938-0235