CIE 1964 color space
Encyclopedia
The CIE 1964 color space, also known as CIEUVW, is based on the CIE 1960 UCS
:
where is the white point
and Y is the luminous tristimulus value of the object. The asterisks in the exponent indicates that the variable represent a more perceptually uniform color space than its predecessor (compare with CIELAB).
Wyszecki invented the UVW color space in order to be able to calculate color difference
s without having to hold the luminance constant. He defined a lightness
index W* by simplifying expressions suggested earlier by Ladd and Pinney, and Glasser et al.. 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 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 is kept constant".
(approximately)."
With the co-efficients thus selected, the color difference
in CIEUVW is simply the Euclidean distance
:
CIE 1960 color space
The CIE 1960 color space is another name for the chromaticity space devised by David MacAdam....
:
where is the white point
White point
A white point is a set of tristimulus values or chromaticity coordinates that serve to define the color "white" in image capture, encoding, or reproduction. Depending on the application, different definitions of white are needed to give acceptable results...
and Y is the luminous tristimulus value of the object. The asterisks in the exponent indicates that the variable represent a more perceptually uniform color space than its predecessor (compare with CIELAB).
Wyszecki invented the UVW color space in order to be able to calculate color difference
Color difference
The difference or distance between two colors is a metric of interest in color science. It allows people to quantify a notion that would otherwise be described with adjectives, to the detriment of anyone whose work is color critical...
s without having to hold the luminance constant. He defined a lightness
Lightness (color)
Lightness is a property of a color, or a dimension of a color space, that is defined in a way to reflect the subjective brightness perception of a color for humans along a lightness–darkness axis. A color's lightness also corresponds to its amplitude.Various color models have an explicit term for...
index W* by simplifying expressions suggested earlier by Ladd and Pinney, and Glasser et al.. 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 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 is kept constant".
Chromaticity and color difference
The chromaticity co-efficients were chosen "on the basis of the spacing of the Munsell system. A lightness difference is assumed to correspond to a chromatic-ness difference (approximately)."With the co-efficients thus selected, the color difference
Color difference
The difference or distance between two colors is a metric of interest in color science. It allows people to quantify a notion that would otherwise be described with adjectives, to the detriment of anyone whose work is color critical...
in CIEUVW is simply the Euclidean distance
Euclidean distance
In mathematics, the Euclidean distance or Euclidean metric is the "ordinary" distance between two points that one would measure with a ruler, and is given by the Pythagorean formula. By using this formula as distance, Euclidean space becomes a metric space...
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