chromaticity coordinates

(optics) The fractional amounts of the x, y, and z primary colors, specified by the International Committee on Illumination, in a color sample; more precisely, x = X/(X + Y + Z),y = Y/(X + Y + Z),z = Z/(X + Y + Z), where X, Y, and Z are the integrals over wavelength λ of the product of the amount of light emerging from the sample per unit wavelength, and the tristimulus values, &xmacr;(λ), &ymacr;(λ), and &zmacr;(λ), respectively.