CIE Lab

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CIE Lab

A color space defined by the Commission Internationale de l'Eclairage (see CIE). In 1931, CIE defined the CIE XYZ color space, which represented all possible colors based on human perception. Like RGB, CIE XYZ has three orthogonal dimensions; however, X, Y and Z do not correspond to real colors. They are simply mathematically convenient with Y carrying the luminance information. CIE is usually represented by a 2D "chromaticity diagram" obtained from the CIE XYZ model.

The CIE XYZ model and chromaticity diagram are not perceptually uniform. A more uniform version of CIE was defined in 1976, officially known as CIE L*a*b*. L* stands for luminance, a* is the red-green axis, and b* is the blue-yellow axis. The asterisks were added to differentiate CIE from another L,a,b model.

A Reference and Intermediary
Although CIE L*a*b* has a large color gamut and is considered the most accurate color model, it is often used as a reference only or as an intermediary for color space conversion. In practice, the RGB and CMYK color spaces are more widely used for display and printing, and HSB and HSL are used for color selection. However, all color spaces, including RGB, CMYK, HSB, HSL and YUV, are subsets of the entire human color gamut as measured and defined by CIE. See color space, RGB, CMYK, YUV, HSB and HSL.


CIE 1976 Chromaticity Diagram
In the original 1931 CIE diagram, the color green seemed to dominate. In 1976, changes were made that displayed perceived colors more uniformly. (Image courtesy of Photo Research, Inc., www.photoresearch.com)
References in periodicals archive ?
The color of rumen was monitoered with the help of Minolta Chroma Meter (Konica Minolta, CR-400- Japan) with a CIELAB Color System for the color values (L* = value designates lightness; a* and b*= color coordinates).
When the CIELAB color coordinates were evaluated, loin area of the outdoor pigs had higher [a.
Pesticide Malathion, tristimulus colorimetry, psychometric attributes CIELAB space.
j] are the average color level of two superpixels in the CIELAB color space, with [I.
Table 1 lists the predicted TSR of a series of gray coatings with the corresponding CIELAB Lightness (L) values for coatings containing NIR-reflective PBr 29.
where a positive value indicates a hue of red and a negative value indicates a green in the CIELAB color space.
The colorimeter measured color along the CIELAB color scale (CIE 1976), which includes L*, a*, and b* values.
Thin layer deposition uniformity control: the international system for color identification CIELAB ("CIE L*a*b*")
Color measurements were analyzed by considering the CIELAB color system [8], Each color is described trough three Cartesian coordinates: [L.
que corresponde a la luminosidad; el angulo del tono, que corresponde a la posicion en rueda de color de 360[grados] con el tono rojo-purpura colocada en el extremo derecho (0[grados]) y los tonos amarillo, verde y azul a 90[grados], 180[grados] y 270[grados] respectivamente; y la saturacion que corresponde a la pureza del color, de acuerdo con la escala CIELAB (McGuire 1992).
Color appearance models such as CIECAM02 are sometimes capable of taking these effects into account and could possibly be used as the basis metrics of illumination quality similar to proposed gamut-area indices but based on dimensions of perceived colorfulness, which grows with luminance, instead of perceived chroma, such as CIELAB C*, which does not grow with luminance.