HCL color space#Implementations

HCL (hue–chroma–luminance) or LCh refers to any of the many cylindrical color space models that are designed to accord with human perception of color with the three parameters. Lch has been adopted by information visualization practitioners to present data without the bias implicit in using varying saturation.{{cite conference | last1 = Ihaka | first1 = Ross | author1-link = Ross Ihaka | title = Colour for Presentation Graphics | book-title = Proceedings of the 3rd International Workshop on Distributed Statistical Computing, Vienna, Austria | editor1-last = Hornik | editor1-first = Kurt | editor2-last = Leisch | editor2-first = Friedrich | editor3-last = Zeileis | editor3-first = Achim | issn = 1609-395X | year = 2003 | url = http://www.ci.tuwien.ac.at/Conferences/DSC-2003/Proceedings/ }}{{cite journal | last1 = Zeileis | first1 = Achim | last2 = Hornik | first2 = Kurt | last3 = Murrell | first3 = Paul | title = Escaping RGBland: Selecting Colors for Statistical Graphics | journal = Computational Statistics & Data Analysis | volume = 53 | issue = 9 | pages = 3259–3270 | year = 2009 | doi = 10.1016/j.csda.2008.11.033 | url = https://epub.wu.ac.at/1692/1/document.pdf }}{{cite journal | last1 = Stauffer | first1 = Reto | last2 = Mayr | first2 = Georg J. | last3 = Dabernig | first3 = Markus | last4 = Zeileis | first4 = Achim | title = Somewhere over the Rainbow: How to Make Effective Use of Colors in Meteorological Visualizations | journal = Bulletin of the American Meteorological Society | volume = 96 | issue = 2 | pages = 203–216 | year = 2015 | doi = 10.1175/BAMS-D-13-00155.1 | bibcode = 2015BAMS...96..203S | hdl = 10419/101098 | hdl-access = free }} They are, in general, designed to have characteristics of both cylindrical translations of the RGB color space, such as HSL and HSV, and the L*a*b* color space.{{multiple image

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| image1 = SRGB gamut within CIELCHab color space mesh.webm

| alt1 = SRGB gamut in CIELCHab space

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| image2 = SRGB gamut within CIELCHuv color space mesh.webm

| alt2 = SRGB gamut in CIELCHuv space

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| footer = The sRGB gamut plotted within the cylindrical CIELCh color spaces. L is the vertical axis; C is the cylinder radius; h is the angle around the circumference. Left: CIELCh_ab; right: CIELCh_uv

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Derivation

= Color-making attributes =

HCL concerns the following attributes of color appearance:

; Hue: The "attribute of a visual sensation according to which an area appears to be similar to one of the perceived colors: red, yellow, green, and blue, or to a combination of two of them".Fairchild (2005), [https://books.google.com/books?id=8_TxzK2B-5MC&pg=PT106 {{nobr|pp. 83–93}}]

; Lightness, value: The "brightness relative to the brightness of a similarly illuminated white".

; Luminance (Y or L_v,Ω): The radiance weighted by the effect of each wavelength on a typical human observer, measured in SI units in candela per square meter ({{nowrap|cd/m²}}). Often the term luminance is used for the relative luminance, Y/Y_n, where Y_n is the luminance of the reference white point.

; Colorfulness: The "attribute of a visual sensation according to which the perceived color of an area appears to be more or less chromatic".

The HSL and HSV color spaces are more intuitive translations of the RGB color space, because they provide a single hue number. However, their luminance variation does not match the way humans perceive color. Perceptually uniform color spaces outperform RGB in cases such as high noise environments.{{cite journal | last1 = Paschos | first1 = G. | year = 2001 | title = Perceptually Uniform Color Spaces for Color Texture Analysis: An Empirical Evaluation | journal = IEEE Transactions on Image Processing | volume = 10 | issue = 6 | pages = 932–937 | doi = 10.1109/83.923289| bibcode = 2001ITIP...10..932P }}

= CIE color spaces =

CIE-based LCh color spaces are transformations of the two chroma values (ab or uv) into the polar coordinate. The source color spaces are still very well-regarded for their uniformity, and the transformation does not cause degradation in this aspect.{{Citation needed|date=May 2025}}

= Sarifuddin, 2005 =

Sarifuddin, noting the lack of blue hue consistency of CIELAB—a common complaint among its users—{{cite journal | last1 = McLellan | first1 = M. R. | last2 = Lind | first2 = L. R. | last3 = Kime | first3 = R. W. | year = 1995 | title = Hue Angle Determinations and Statistical Analysis for Multiquadrant Hunter L,a,b Data| journal = Journal of Food Quality | volume = 18 | issue = 3 | pages = 235–240 | doi = 10.1111/j.1745-4557.1995.tb00377.x| doi-access = free }} decided to make their own color space by mashing up some of the features.{{cite conference |last1=Sarifuddin |first1=M. |last2=Missaoui |first2=Rokia |date=2005 |title=A New Perceptually Uniform Color Space with Associated Color Similarity Measure for Content-Based Image and Video Retrieval |url=http://pdfs.semanticscholar.org/206c/a4c4bb4a5b6c7b614b8a8f4461c0c6b87710.pdf |conference=Multimedia Information Retrieval Workshop, 28th Annual ACM SIGIR Conference |archive-url=https://web.archive.org/web/20190220074017/http://pdfs.semanticscholar.org/206c/a4c4bb4a5b6c7b614b8a8f4461c0c6b87710.pdf |archive-date=2019-02-20 |url-status=dead |name-list-style=amp |s2cid=17570716}}. [https://www.semanticscholar.org/paper/206ca4c4bb4a5b6c7b614b8a8f4461c0c6b87710 Abstract]/[http://w3.uqo.ca/missaoui/Publications/TRColorSpace.zip long-form corrected report]{{Clarify|reason="Mashing up" with what? And how is this relevant?|date=May 2025}}

= Other color appearance models =

In general, any color appearance model with a lightness and two chroma components can also be transformed into a HCL-type color space by turning the chroma components into polar coordinates.{{Citation needed|date=May 2025}}

References

External links

[https://hclwizard.org/ HCL Wizard online color apps]
[https://colorspace.R-Forge.R-project.org/ colorspace: HCL-Based Color Tools and Palettes in R]
[http://tools.medialab.sciences-po.fr/iwanthue/theory.php Generating random colors]
[http://vis4.net/blog/posts/avoid-equidistant-hsv-colors/ How To Avoid Equidistant HSV Colors]
[http://cscheid.net/2012/02/16/hcl-color-space-blues.html Color Space Blues]
[https://cscheid.github.io/lux/demos/hcl/hcl.html HCL demo]

Category:Color space