Chromaticity is an objective specification of the quality of a color regardless of its luminance. Chromaticity consists of two independent parameters, often specified as hue (h) and colorfulness (s), where the latter is alternatively called saturation, chroma, intensity,[1] or excitation purity.[2][3] This number of parameters follows from trichromacy of vision of most humans, which is assumed by most models in color science.
The CIE 1931 xy chromaticity space, also showing the chromaticities of black-body light sources of various temperatures, and lines of constant correlated color temperature3D chromaticity diagram of the WideGamutRGB color space
In color science, the white point of an illuminant or of a display is a neutral reference characterized by a chromaticity; all other chromaticities may be defined in relation to this reference using polar coordinates. The hue is the angular component, and the purity is the radial component, normalized[clarification needed] by the maximum radius for that hue.
Some color spaces separate the three dimensions of color into one luminance dimension and a pair of chromaticity dimensions. For example, the white point of an sRGB display is an x, y chromaticity of (0.3127, 0.3290), where x and y coordinates are used in the xyY space.
(u′, v′), the chromaticity in CIELUV, is a fairly perceptually uniform presentation of the chromaticity as (another than in CIE 1931) planar Euclidean shape. This presentation is a projective transformation of the CIE 1931 chromaticity diagram above.
These pairs determine a chromaticity as affine coordinates on a triangle in a 2D-space, which contains all possible chromaticities. These x and y are used because of simplicity of expression in CIE 1931 (see below) and have no inherent advantage. Other coordinate systems on the same X-Y-Z triangle, or other color triangles, can be used.
On the other hand, some color spaces such as RGB and XYZ do not separate out chromaticity, but chromaticity is defined by a mapping that normalizes out intensity, and its coordinates, such as r and g or x and y, can be calculated through the division operation, such as x =X/X + Y + Z, and so on.
The xyY space is a cross between the CIE XYZ and its normalized chromaticity coordinates xyz, such that the luminance Y is preserved and augmented with just the required two chromaticity dimensions.[4]
See alsoedit
Wikimedia Commons has media related to Chromatic diagrams.
^In modern terminology the word "intensity" may refer to lightness, not to colorfulness.
^Emil Wolf (1961). Progress in Optics. North Holland Pub. Co.
^Leslie D. Stroebel, Richard D. Zakia (1993). The Focal Encyclopedia of Photography. Focal Press. p. 124. ISBN978-0-240-51417-8. chromaticity hue saturation chroma colorfulness purity.
^Charles A. Poynton (2003). Digital Video and HDTV: Algorithms and Interfaces. Morgan Kaufmann. ISBN978-1-55860-792-7.
External linksedit
Stanford University CS 178 interactive Flash demo explaining chromaticity diagrams.
JOES application software for calculation and plotting of CIE 1931 and 1976 from spectra[1]
^Ćirić, Aleksandar; Stojadinović, Stevan; Sekulić, Milica; Dramićanin, Miroslav D. (January 2019). "JOES: An application software for Judd-Ofelt analysis from Eu3+ emission spectra". Journal of Luminescence. 205: 351–356. Bibcode:2019JLum..205..351C. doi:10.1016/j.jlumin.2018.09.048. S2CID 105828989.
January 01, 1970
chromaticity, album, tony, macalpine, album, objective, specification, quality, color, regardless, luminance, consists, independent, parameters, often, specified, colorfulness, where, latter, alternatively, called, saturation, chroma, intensity, excitation, pu. For the album by Tony MacAlpine see Chromaticity album Chromaticity is an objective specification of the quality of a color regardless of its luminance Chromaticity consists of two independent parameters often specified as hue h and colorfulness s where the latter is alternatively called saturation chroma intensity 1 or excitation purity 2 3 This number of parameters follows from trichromacy of vision of most humans which is assumed by most models in color science The CIE 1931 xy chromaticity space also showing the chromaticities of black body light sources of various temperatures and lines of constant correlated color temperature 3D chromaticity diagram of the WideGamutRGB color space Contents 1 Quantitative description 2 See also 3 References 4 External linksQuantitative description editIn color science the white point of an illuminant or of a display is a neutral reference characterized by a chromaticity all other chromaticities may be defined in relation to this reference using polar coordinates The hue is the angular component and the purity is the radial component normalized clarification needed by the maximum radius for that hue Purity is roughly equivalent to the term saturation in the HSV color model The property hue is as used in general color theory and in specific color models such as HSL and HSV color spaces though it is more perceptually uniform in color models such as Munsell CIELAB or CIECAM02 Some color spaces separate the three dimensions of color into one luminance dimension and a pair of chromaticity dimensions For example the white point of an sRGB display is an x y chromaticity of 0 3127 0 3290 where x and y coordinates are used in the xyY space nbsp u v the chromaticity in CIELUV is a fairly perceptually uniform presentation of the chromaticity as another than in CIE 1931 planar Euclidean shape This presentation is a projective transformation of the CIE 1931 chromaticity diagram above These pairs determine a chromaticity as affine coordinates on a triangle in a 2D space which contains all possible chromaticities These x and y are used because of simplicity of expression in CIE 1931 see below and have no inherent advantage Other coordinate systems on the same X Y Z triangle or other color triangles can be used On the other hand some color spaces such as RGB and XYZ do not separate out chromaticity but chromaticity is defined by a mapping that normalizes out intensity and its coordinates such as r and g or x and y can be calculated through the division operation such as x X X Y Z and so on The xyY space is a cross between the CIE XYZ and its normalized chromaticity coordinates xyz such that the luminance Y is preserved and augmented with just the required two chromaticity dimensions 4 See also edit nbsp Wikimedia Commons has media related to Chromatic diagrams CIE xyY chromaticity diagram Chrominance rg chromaticity Impossible color Color index in astronomyReferences edit In modern terminology the word intensity may refer to lightness not to colorfulness Emil Wolf 1961 Progress in Optics North Holland Pub Co Leslie D Stroebel Richard D Zakia 1993 The Focal Encyclopedia of Photography Focal Press p 124 ISBN 978 0 240 51417 8 chromaticity hue saturation chroma colorfulness purity Charles A Poynton 2003 Digital Video and HDTV Algorithms and Interfaces Morgan Kaufmann ISBN 978 1 55860 792 7 External links editStanford University CS 178 interactive Flash demo explaining chromaticity diagrams JOES application software for calculation and plotting of CIE 1931 and 1976 from spectra 1 Ciric Aleksandar Stojadinovic Stevan Sekulic Milica Dramicanin Miroslav D January 2019 JOES An application software for Judd Ofelt analysis from Eu3 emission spectra Journal of Luminescence 205 351 356 Bibcode 2019JLum 205 351C doi 10 1016 j jlumin 2018 09 048 S2CID 105828989 Retrieved from https en wikipedia org w index php title Chromaticity amp oldid 1223658564, wikipedia, wiki, book, books, library,
