![]() The three coordinates of CIELAB represent the lightness of the color ( L* = 0 yields black and L* = 100 indicates diffuse white specular white may be higher), its position between magenta and green ( a*, where negative values indicate green and positive values indicate magenta) and its position between yellow and blue ( b*, where negative values indicate blue and positive values indicate yellow). a and b are the horizontal axes L is the vertical axis. The sRGB gamut ( left) and visible gamut under D65 illumination ( right) plotted within the CIELAB color space. This results in an effective power curve with an exponent of approximately 0.43 which represents the human eye's response to light under daylight ( photopic) conditions. The lightness value, L* in CIELAB is calculated using the cube root of the relative luminance with an offset near black. While the intention behind CIELAB was to create a space that was more perceptually uniform than CIEXYZ using only a simple formula, CIELAB is known to lack perceptual uniformity, particularly in the area of blue hues. The International Color Consortium largely supports the printing industry and uses D50 with either CIEXYZ or CIELAB in the Profile Connection Space, for v2 and v4 ICC profiles. D65 is used in the vast majority industries and applications, with the notable exception being the printing industry which uses D50. For instance, if integer math is being used it is common to clamp a* and b* in the range of −128 to 127.ĬIELAB is calculated relative to a reference white, for which the CIE recommends the use of CIE Standard illuminant D65. Nevertheless, software implementations often clamp these values for practical reasons. The a* and b* axes are unbounded and depending on the reference white they can easily exceed ☑50 to cover the human gamut. The b* axis represents the blue–yellow opponents, with negative numbers toward blue and positive toward yellow. The a* axis is relative to the green–magenta opponent colors, with negative values toward green and positive values toward magenta. The lightness value, L*, also referred to as "Lstar," defines black at 0 and white at 100. ![]() ![]() It is based on the opponent color model of human vision, where red and green form an opponent pair and blue and yellow form an opponent pair. The CIELAB space is three-dimensional and covers the entire gamut (range) of human color perception. ( April 2023) ( Learn how and when to remove this template message) Please help improve this section if you can. The specific problem is: Remove duplications. This section may require cleanup to meet Wikipedia's quality standards. The colors it defines are not relative to any particular device such as a computer monitor or a printer, but instead relate to the CIE standard observer which is an averaging of the results of color matching experiments under laboratory conditions. Like the CIEXYZ space it derives from, CIELAB color space is a device-independent, "standard observer" model. While the LAB space is not truly perceptually uniform, it nevertheless is useful in industry for detecting small differences in color. CIELAB was intended as a perceptually uniform space, where a given numerical change corresponds to a similar perceived change in color. It expresses color as three values: L* for perceptual lightness and a* and b* for the four unique colors of human vision: red, green, blue and yellow. The CIELAB color space, also referred to as L*a*b*, is a color space defined by the International Commission on Illumination (abbreviated CIE) in 1976. Each axis of each square ranges from −128 to 127. ( November 2010) ( Learn how and when to remove this template message)ĬIELAB color space top view CIELAB color space front view The CIE 1976 ( L*, a*, b*) color space (CIELAB), showing only colors that fit within the sRGB gamut (and can therefore be displayed on a typical computer display). Please help improve it to make it understandable to non-experts, without removing the technical details. This article may be too technical for most readers to understand.
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