CIE XYZ Color System

The CIE XYZ color system is the standard colorimetric system defined by the "Commission Internationale de l'Eclairage" in 1931.

Specifies an additive mixture of three color primaries called X, Y and Z. The spectral composition of these primaries is tabulated by the standard. Since negative intensities are involved, the primaries cannot be physically implemented. Anyway, the XYZ system is very useful because of its absolute device independence and its ability to cover the whole gamut of the visible spectrum.

Reduced xyz coordinates (X, Y and Z over their sum) are sometimes used.