Like black and white newspaper pictures, colour photographs are also reproduced as patterns of dots. The dots are of three different colours – yellow, magenta and cyan (greenish blue). Viewed from a distance, combinations of different sized dots of these colours merge to simulate the whole spectrum.
Colour printing depends on the principle that all colours can be produced by combining in different proportions these three colours.
Filter photography
The first step in reproduction is to ‘separate’ the colours by photographing them through filters.
The three colour images are then screened, as in a black and white photograph, to produce a pattern of dots. From each colour a printing plate is made. A black plate is also made to add sharpness, and the method is known as the four-colour process. Nowadays, this is usually done by electronic scanners, rather than the traditional cameras.
Picture Credit : Google