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 ?
In the CIELAB 1976 system, L* is a measure of whiteness, while a* measures color in the red-green direction, and b* measures color in the yellow-blue direction.
A Switching Vector Median Filter Based on CIELAB color Space for Color Image Restoration.
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.
yellow-blue) were shown in the color system CIELAB and assessed at three different points of the muscle surface using illuminant D65 and observational angle of 10[degrees].
The color change of samples was measured using a Konica Minolta Spectrophotometer (CM-2002) with the CIELAB color system in SCI mode (specular component included).
Segmentation and edge detection of colour images using CIELAB colour space and edge detectors, Available from: http://0-ieeexplore.
A cor dos files do peito foi determinada por meio de um colorimetro (Minolta), no sistema CIELAB, em que foram avaliados os parametros L* (luminosidade), a* (teor de vermelho) e b* (teor de amarelo).
For a typical printer, the gamut volume in CIELAB color space is only 50 to 80 % of that of a typical CRT monitor (Katoh, 1997).
The appearance was evaluated by looking at relative color attributes measured by the CIELAB method, which measures luminosity (L *) and chromatic coordinates ([a.
Equipped with the company's patented CIELAB engine that offers advanced real-time color processing, the TXG06ac camera requires only one CCD sensor to deliver high quality color images comparable to those taken by 3CCD cameras.