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RGB Colour Model

The RGB colour model adds the three primary colours, red, green and blue in various proportions to black (no light), and is consequently known as an additive model. An eight-bit, 256-step scale for each of the primary colours, used in this example, allows about 16.7 million different colours to be produced (256 x 256 x 256). Each of the three primary colours is allocated a value in the range 0 - 255 for each pixel, giving 24-bit colour. True green has a red value of 0, a green value of 255 and a blue value of 0. Yellow has a red value of 255, a green value of 255 and a blue value of 0. Orange might have values of 255 for red, 128 for green and 0 for blue. White results from a combination of all three primary colours.