Additive color
From Free net encyclopedia
An additive color system involves light emitted directly from a source or illuminant of some sort. The additive reproduction process usually uses red, green and blue light to produce the other colors. See also RGB color model. Combining one of these additive primary colors with another in equal amounts produces the additive secondary colors cyan, magenta, and yellow. Combining all three primary lights (colors) in equal intensities produces white. Varying the luminosity of each light (color) eventually reveals the full gamut of those three lights (colors).
Results obtained when mixing additive colors are often counterintuitive for people accustomed to the more everyday subtractive color system of pigments, dyes, inks and other substances which present color to the eye by reflection rather than emission. Many will insist that red-blue-yellow are the "primary colors" in an absolute sense because no combination of other (subtractive) colors will produce them. However, in additive color, red + green = yellow and no simple combination will yield green. In this sense red-blue-green may have the truer claim to being absolute primaries, since additive light works with color directly from its originating source (light).
Computer monitors and televisions are the most common application of additive color.
It should be noted that additive color is a result of the way the eye detects color, and is not a property of light. There is a vast difference between Yellow light, with a wavelength of approximately 580nm, and a mixture of red and green light. However, both stimulate our eyes in a similar manner, so we do not detect the difference. (see eye (cytology), color vision.)
James Clerk Maxwell is credited as being the father of additive color: He had the photographer Thomas Sutton photograph a tartan ribbon three times, each time with a different colour filter over the lens. The three images were developed and then projected onto a screen with three different projectors, each equipped with the same colour filter used to take its image. When brought into register, the three images formed a full colour image, thus demonstrating the principles of additive color.
See also: subtractive colorcs:Aditivní míchání barev de:Additive Farbsynthese fr:Synthèse additive it:Mescolanza additiva nl:Additieve kleurmenging sv:Additiv färgblandning vi:Phối màu phát xạ es:Síntesis aditiva de color