People eye on color of perception is a complex of process, to will color of description be quantitative, international lighting Association (CIE) according to standard observation who of Visual experiment, will people eye on different wavelength of radiant energy by caused of Visual sense be records, calculation out red, and green, and blue three primaries of color function, after mathematics conversion hòu that have so-called of CIE1931ColorMatchingFunction (x ((), y ((), z (()), and according to this a color function, Subsequent development of several color metric definitions, make it possible to use to describe colour.
