Xref: utzoo sci.electronics:3880 rec.audio:8416 Path: utzoo!attcan!uunet!ncrlnk!ncrcae!ece-csc!ncsuvx!gatech!rutgers!njin!princeton!siemens!demon!fwb From: fwb@demon.siemens.com (Frederic W. Brehm) Newsgroups: sci.electronics,rec.audio Subject: Re: Looking for Blue LEDs Keywords: blue blue blue, not yellow or red or green Message-ID: <2214@siemens.UUCP> Date: 23 Sep 88 17:48:01 GMT References: <1138@nmtsun.nmt.edu> <862@ritcv.UUCP> <255@rna.UUCP> <4422@lynx.UUCP> <871@ritcv.UUCP> Sender: news@siemens.UUCP Reply-To: fwb@demon.UUCP (Frederic W. Brehm) Organization: Siemens Research and Technology Laboratories Lines: 32 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? I thought that red, yellow and blue were the "primary" colors until I took Physics II in high school. Don't believe everything you learned in elementary school. Red, green and blue are the ADDITIVE primary colors. That means that you add different proportions of these three to make all of the different colors. Color CRT screens and the projection TVs add the light from the different phosphors to produce color. The SUBTRACTIVE primaries are cyan (kind of blueish-green), magenta (kind of reddish-purple), and yellow. This means that you subtract different proportions of these three from white light to produce all the different colors. Printing technologies use this method. There is a color wheel which describes the relationships between the additive and subtractive primaries. You can probably find it in a good book on color photography. Fred ---------------------------------------------------------------------------- Frederic W. Brehm phone: (609)-734-3336 Siemens Corporate Research uucp: princeton!siemens!demon!fwb 755 College Road East internet: fwb@demon.siemens.com Princeton, NJ 08540 "From there to here, from here to there, funny things are everywhere." - Dr. Seuss