CIE 1960 color space
The CIE UCS chromaticity diagram is a color chart. The CIE chromaticity diagram is not perceptually, as MacAdam 1940 could prove in an experiment. This means that the color chart is indeed correct for the mathematical description of colors, however, is not matched to the color perception of the human eye. When measuring two colors of the same brightness, then one speaks of a perceptible color difference - the color distance threshold.
MacAdam was able to show that the color distance threshold has the form of ellipses in the chromaticity diagram (by a factor of 10 shown). These show how strong must be different in each case two color stimuli, so that the color difference is visible to the eye. The green color in the color space take a very wide space which the red and the blue regions are smaller.
By distorting the standard color chart the UCS chromaticity diagram has emerged. The ellipses are distorted by mathematical transformation into circles, so as to obtain the delta E equidistance greater power. x and y are transformed to u and v:
This system was adopted by the CIE based on MacAdam 1960. To improve the equidistance, the UV color chart 1976 is converted into the system u'v '. v is hereby increased by 50 %:
The CIE UCS chromaticity diagram should be used in sensation proper display of colors. It should be noted, however, that this color chart is only approximately equidistant.
The color difference is calculated as the Euclidean distance.
Indicates how strongly two colors differ perceptually from each other.