CIE 1964 color space
The CIE 1964 (U*, V*, W*) color space, also known as CIEUVW, is based on the CIE 1960 UCS:[1]
where (u0, v0) is the
CIELAB
).
Wyszecki invented the UVW color space in order to be able to calculate
lightness index W* by simplifying expressions suggested earlier by Ladd and Pinney,[2] and Glasser et al..[3] The chromaticity components U* and V* are defined such that the white point maps to the origin, as in Adams chromatic valence color spaces. This arrangement has the benefit of being able to express the loci of chromaticities with constant saturation simply as (U*)2 + (V*)2 = C for a constant C. Furthermore, the chromaticity axes are scaled by the lightness "so as to account for the apparent increase or decrease in saturation when the lightness index is increased or decreased, respectively, and the chromaticity (u, v) is kept constant".[4]
Chromaticity and color difference
The chromaticity coefficients were chosen "on the basis of the spacing of the Munsell system. A lightness difference ΔW = 1 is assumed to correspond to a chromaticness difference √ΔU2 + ΔV2 = 13 (approximately)."[4]
With the coefficients thus selected, the color difference in CIEUVW is simply the Euclidean distance:
References
- Wiley Interscience. p. 81.
- .
- .
- ^ . Note: The asterisks are not used in the paper.
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