CRTs produce color by emission and uses the RGB model. Printers produce color by reflective light so it is a subtractive process and uses a model based on the colors: Cyan, Magenta, Yellow.
Remember that cyan = green + blue, so light reflected from a cyan pigment has no red component, i.e., the red is absorbed by cyan. Similarly magenta subtracts green and yellow subtracts blue. Printers usually use four colors: cyan, yellow, magenta and black. This is because cyan, yellow, and magenta together produce a dark gray rather than a true black.
The conversion between the RGB and CMY is easily computed as below:
C 1 - R M = 1 - G Y 1 - B For example: C = 1 - R R 1 - C G = 1 - M B 1 - Y For example: R = 1 - C
Main Color page
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