Additive colours are produced through the addition of different coloured light. In theory, every colour can be produced by mixing the primary colours of the visible light spectrum: red, green and blue (RGB). Combining all three primary colours to equal parts produces white. The colour vision of the human eye works through red-, green- and blue- sensitive sensory cells. When, for example, red and green rays of light reach the corresponding receptor cells in the eye, we see the mixed colour yellow. When all three colour receptors are stimulated, the eye sees white. RGB is the usual additive colour system and is used predominantly for television screens, computer monitors and scanners. Combining two of the primary colours in equal parts produces the secondary colours cyan, magenta and yellow, which in turn form the basic colours of the subtractive colour system CMYK).
Red, green and blue (RGB), the colours of light used in monitors and scanners, which give the perception of white when added together.