TRISTIMULUS

The 'tristimulus values' of a test color are the amounts of the three primary colors in a three-component color model needed to match that test color. The tristimulus values are most often given in the CIE 1931 color space, in which they are denoted $X$, $Y$, and $Z$.
Each color can also be represented in terms of its chromaticity coordinates, which represent the chromaticity (colorfulness) of a test color independent of how bright it is. The CIE 1931 chromaticity coordinates $x$, $y$, and $z$ are calculated from the three tristimulus values as:
$$
x=rac{X}{X+Y+Z}

$$
y=rac{Y}{X+Y+Z}

$$
z=rac{Z}{X+Y+Z}

Chromaticity coordinates measure the balance of the three primaries that match a test color, so $x+y+z=1$ always.

Contents

Audio tristimulus

References

Audio tristimulus

By analogy with the above, tristimulus parameters for audio have been proposed and used, based on the strengths of the harmonics in a sound.

References

★ Hunt, R. W. ''Measuring colour'' 3rd ed. England: Fountain Press, 1998. ISBN 0-86343-387-1. See pgs. 39-46 for the basis in human eye physiology of three-component color models, and 54-57 for chromaticity coordinates.