A colorspace created by Commission Internationale de L'Eclairage. Known as "capX, capY, capZ" XYZ tristimulus values are derived from the CIE's color matching functions of 1931. XYZ space is useful in that it contains all other color spaces. It's only major defficiency is its lack of perceptual uniformity, a problem corrected with L*u*v* and L*a*b*. L*u*v* and L*a*b* remain too computationally intensive for most applications.
Due to the non-uniform distribution of cones and rods on the human retina, the CIE 1931 standard observer (an empirical composite of many test subjects) is only valid for the fovea vision of the eye. This is roughly two degrees of radial vision from view center. As the three variants of cones in our eyes respond to different wavelengths of light differently, the standard observer was derived from three components. The monochromatic stimulus components used for the standard observer are 435.8nm, 546.1nm and 700nm.