Besides a quantitative estimation of colour by means of the colour schedule it is possible to define vzaimodopolnitelnye colours. For this purpose it is necessary to draw a straight line through a point on a contour, corresponding to necessary colour, and the central point E corresponding to white colour, having prolonged it before crossing from a contour opposite side. The received point of intersection characterises length of a wave of a complementary colour.
Colour, i.e. Unequivocal expression of the characteristic of colour of this or that concrete object, in standard kolorimetricheskoj to system is defined in practice or by its identification with a certain colour field of the atlas which characteristic is known, or fotometricheski by means of optical devices, photometers or spektrofotometrov.