Everything about Cieluv Color Space totally explained
In
colorimetry, the
CIE 1976 (L*, u*, v*) color space, also known as the
CIELUV color space, is a
color space adopted by the
International Commission on Illumination (CIE) in 1976, as a simple-to-compute transformation of the 1931
CIE XYZ color space, but which attempted
perceptual uniformity. It is extensively used for applications such as computer graphics which deal with colored lights. Although additive mixtures of different colored lights will fall on a line in CIELUV's uniform
chromaticity diagram (dubbed the
CIE 1976 UCS), such additive mixtures will not, contrary to popular belief, fall along a line in the CIELUV color space unless the mixtures are constant in
lightness.
Historical background
CIELUV is an
Adams chromatic valence color space, and is an update of the
CIE 1964 color space (CIEUVW). The differences include a slightly modified
lightness scale, and a modified uniform chromaticity scale (in which one of the coordinates,
v', is 1.5 times as large as
v, its
1960 predecessor. CIELUV and
CIELAB were adopted simultaneously by the CIE when no clear consensus could be formed behind only one or the other of these two color spaces.
CIELUV uses Judd-type (translational)
white point adaptation (in contrast with CIELAB, which uses a "wrong"
von Kries transform). This can produce useful results when working with a single illuminant, but can predict
imaginary colors (for example, outside the
spectral locus) when attempting to use it as a
chromatic adaptation transform. The translational adaptation transform used in CIELUV has also been shown to perform poorly in predicting corresponding colors.
XYZ → CIELUV, CIELUV → XYZ conversions
For typical images, u
* and v
* range ±100. By definition,
