On Apr 10, 2:32 pm, John Salerno <[EMAIL PROTECTED]> wrote: > Sorry for this non-Python question, but since it's computer related I > know you guys will have an answer, and I don't really know where else to > ask. Mainly I'm just curious anyway. > > I'm wondering, why do computers use a RGB color scheme instead of the > primary colors? Is there something you can't do with yellow? It seems > weird that RGB can be combined to make all colors, when that's supposed > to be the job of the primary colors. I'm sure there some technical > computer-related reason that it had to be this way. > > Thanks.
See this link: http://www.rgbworld.com/color.html The "red-yellow-blue" system we used in elementary school art classes corresponded to the color mixing capabilities available using the Tempra paint technology at hand. At the RGBworld URL, the web page shows how paints and inks follow a "subtractive" color system (called CMY for cyan-magenta-yellow, instead of blue-red-yellow, but close enough), in that paint reflects a given color by subtracting out all frequencies that are not that color. So mixing two subtractive filters follows a subtractive color "algebra". However, computer monitors do not follow a substractive scheme, but rather an additive one, by adding brightness along red-green-and-blue (RGB) dimensions, mixing red and green light to get yellow. This raises an interesting problem when *printing* a color image. You cannot just render the RGB colors from the monitor's additive system into CMY colors on your inkjet printer's subtractive system. Google for "RGB color" and you will be presented with a long list of references for dealing with this issue, including several competing standards on how to handle it. Even the Wikipedia article on RGB colors is largely devoted to this issue (as opposed to your more common question). -- Paul -- http://mail.python.org/mailman/listinfo/python-list
