This is a list of color spaces, grouped by the color model that is used for part of their specification.
Color models can be based on physics or human perception. Physical descriptions of color can be additive (describes mixing of light, RGB) or subtractive (describes mixing of pigment or removal of light, CMYK). Descriptions based on human perception are based on some experimental results on humans. Some models and their variants are employed in parts of the color spaces listed below. [1]
Instead of being based on color mixture, they are based on human experience or phenomenology.
CIE 1931 XYZ was the first attempt to produce a color space based on measurements of human color perception and the basis for almost all other color spaces.
Measurements over a larger field of view than the "CIE 1931 XYZ" color space which produces slightly different results.
Uniform color spaces (UCSs) are built such that the same geometrical distance anywhere in the color space reflects the same amount of perceived color difference. There have been many attempts at building such a color space.
As human vision has three components, the space is necessarily 3D; it is generally assigned such that one is the lightness and the other two the chroma. A uniform color space is useful for a wide range of tasks. It can be used to calculate color difference or to pick colors in a visually harmonious way, for example.
A modification of "CIE 1931 XYZ" to display color differences more conveniently. The CIELUV space is useful for additive mixtures of lights, due to its linear addition properties (human hue perception does not respect light addition, however). [2]
CIELAB produces a color space that is more perceptually linear than other color spaces. Perceptually linear means that a change of the same amount in a color value should produce a change of about the same visual importance. CIELAB has almost entirely replaced an alternative related Lab color space called “Hunter Lab”. This space is commonly used for surface colors, but not for mixtures of (transmitted) light. [2]
HSLuv preserves the lightness and hue components of CIELUV LCh and stretches its chroma so that every color has the same range, defined as a percentage.
CIELAB and CIELUV are soon recognized to be insufficient to explain the entire range of color phenomena. A range of increasingly complex color appearance models appeared to model the behavior of human vision under different viewing conditions, but ended up less used due to the added inputs required and overall algorithmic complexity.
In addition, the performance of the 1976 color spaces under different viewing conditions is not their only problem. Even under the default reference viewing condition, CIELAB is known to poorly work in blue hues. For a standard dynamic range and a fixed viewing condition, it turns out that CIELAB's simple structure suffices as long as better coefficients are used.
The IPT color space of 1998 uses new data about hue to greatly improve on CIELAB's non-constant lines of hue, [3] although it still leaves much to be desired in its prediction of colorfulness and lightness. OKLab [4] [5] uses IPT data for hue and a modern CAM (CAM16) to generate lightness and colorfulness data, resulting in an improved fit over human perception under the same structure. [6]
RGB (red, green, blue) describes the chromaticity component of a given color, when excluding luminance. RGB itself is not a color space, it is a color model. There are many different color spaces that employ this color model to describe their chromaticities because the R/G/B chromaticities are one facet for reproducing color in CRT & LED displays.
The sRGB color space (standard red, green, blue) was created jointly by Hewlett-Packard and Microsoft for use on the Internet. It has been endorsed by the W3C, Exif, Intel, Pantone, Corel, and many other industry players. It is also well accepted by open-source software such as the GIMP, and is used in proprietary and open graphics file formats such as SVG.
sRGB is intended as a common color space for the creation of images for viewing on the Internet and World Wide Web (WWW). The resultant color space closely approximates a Gamma correction of 2.2, [7] the average response of a CRT display to linear voltage levels.
The Adobe RGB color space was developed by Adobe Systems in 1998. It was designed to encompass most of the colors achievable on CMYK color printers, but by using RGB primary chromaticities on a device such as the computer display. The Adobe RGB color space encompasses roughly 50% of the visible colors specified by the Lab color space, improving upon the gamut of the sRGB color space primarily in cyan-greens.
The Adobe Wide Gamut RGB color space was developed by Adobe Systems as an alternative to the standard sRGB color space. It is able to store a wider range of color values than sRGB. The Wide Gamut color space is an expanded version of the Adobe RGB color space, developed in 1998. As a comparison, the Adobe Wide Gamut RGB color space encompasses 77.6% of the visible colors specified by the Lab color space, whilst the standard Adobe RGB color space covers just 50.6%.
One of the downsides to this color space is that approximately 8% of the colors representable are imaginary colors that do not exist and are not representable in any medium. [8] This means that potential color accuracy is wasted by reserving these unnecessary colors.
Rec. 2100 is a color space standardized by ITU and used for HDR-TV. It has a peak luminance of at least 1,000 cd/m2 [9] (higher than the 100 cd/m2 limit of SDR and color spaces such as Rec. 709 and Rec. 2020). [10] [11] [12] It uses a non-gamma transfer function (PQ or HLG) and system colorimetry (chromaticity of color primaries and white point) identical to Rec. 2020 system colorimetry. [9]
The analogue YUV and digital YCbCr refer to a variety of linear methods to try to separate lightness from chroma signals in an RGB input using linear combination. As the input RGB values are gamma-corrected, such a separation does not truly produce lightness and two chroma signals, but a "luma" signal and two "chrominance" signals instead.
YUV: as human eyes have lower resolution in their color perception, it is more economic to put more of the bandwidth in encoding Luma. The same principle is used in YCC. In YCC, separating also has the added benefit of removing most of the correlation between the input channels, therefore providing better compression.
YCoCg is a version of YCbCr with extremely simple coefficients. It results in faster computation, lossless conversion, and apparently better decorrelation.
ICtCp is used similarly to YCC in video compression, but is more appropriately described as a high dynamic range uniform color space.
Other similar color spaces:
Cylindrical transformations seek to turn a color model into three components: the lightness, the colorfulness, and the hue.
HSV and HSL are transformations of Cartesian RGB primaries (usually sRGB), and their components and colorimetry are relative to the colorspace from which they are derived. HSV (hue, saturation, value), also known as HSB (hue, saturation, brightness), is often used by artists because it is often more natural to think about a color in terms of hue and saturation than in terms of additive or subtractive color components. HSL (hue, saturation, lightness or luminance), also known as HSI (hue, saturation, intensity) or HSD (hue, saturation, darkness), is quite similar to HSV, with "lightness" replacing "brightness". The difference is that a perfectly light color in HSL is pure white; but a perfectly bright color in HSV is analogous to shining a white light on a colored object. I.e. shining a bright white light on a red object causes the object to still appear red, just brighter and more intense. Shining a dim light on a red object causes the object to appear darker and less bright.
The issue with both HSV and HSL is that these approaches do not effectively separate colour into their three value components according to human perception of color.[ citation needed ] This can be seen when the saturation settings are altered — it is quite easy to notice the difference in perceptual lightness despite the "V" or "L" setting being fixed.
For uniform color spaces that already have a lightness component, the transformation only involves rearranging the two chroma values into colorfulness (C) and hue (h).
CIELChab and CIELChuv are cylindrical transformations of the CIELAB and CIELUV color spaces, respectively. The cylindrical coordinates C* (chroma, relative saturation) and h° (hue angle, angle of the hue in the color wheel) are specified. The CIELAB and CIELUV coordinate L* (lightness) remains unchanged.
The newer UCS systems can also be applied to a similar transform. In fact, both IPT and OKLab/OKLCH are designed for hue uniformity, a feature that is only explicitly shown after a cylindrical transformation.
CMYK is used in the printing process, because it describes what kinds of inks are needed to be applied so the light reflected from the substrate and through the inks produces a given color. One starts with a white substrate (canvas, page, etc.), and uses ink to subtract color from white to create an image. CMYK stores ink values for cyan, magenta, yellow and black. There are many CMYK colorspaces for different sets of inks, substrates, and press characteristics (which change the dot gain or transfer function for each ink and thus change the appearance).
Early color spaces had two components. They largely ignored blue light because the added complexity of a three-component process provided only a marginal increase in fidelity when compared to the jump from monochrome to two-component color.
In color theory, hue is one of the main properties of a color, defined technically in the CIECAM02 model as "the degree to which a stimulus can be described as similar to or different from stimuli that are described as red, orange, yellow, green, blue, violet," within certain theories of color vision.
The Natural Color System (NCS) is a proprietary perceptual color model. It is based on the color opponency hypothesis of color vision, first proposed by German physiologist Ewald Hering. The current version of the NCS was developed by the Swedish Colour Centre Foundation, from 1964 onwards. The research team consisted of Anders Hård, Lars Sivik and Gunnar Tonnquist, who in 1997 received the AIC Judd award for their work. The system is based entirely on the phenomenology of human perception and not on color mixing. It is illustrated by a color atlas, marketed by NCS Colour AB in Stockholm.
In colorimetry, the Munsell color system is a color space that specifies colors based on three properties of color: hue, chroma, and value (lightness). It was created by Albert H. Munsell in the first decade of the 20th century and adopted by the United States Department of Agriculture (USDA) as the official color system for soil research in the 1930s.
HSL and HSV are the two most common cylindrical-coordinate representations of points in an RGB color model. The two representations rearrange the geometry of RGB in an attempt to be more intuitive and perceptually relevant than the cartesian (cube) representation. Developed in the 1970s for computer graphics applications, HSL and HSV are used today in color pickers, in image editing software, and less commonly in image analysis and computer vision.
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, or excitation purity. This number of parameters follows from trichromacy of vision of most humans, which is assumed by most models in color science.
The CIELAB color space, also referred to as L*a*b*, is a color space defined by the International Commission on Illumination in 1976. 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. CIELAB was intended as a perceptually uniform space, where a given numerical change corresponds to a similar perceived change in color. While the LAB space is not truly perceptually uniform, it nevertheless is useful in industry for detecting small differences in color.
In color reproduction and colorimetry, a gamut, or color gamut, is a convex set containing the colors that can be accurately represented, i.e. reproduced by an output device or measured by an input device. Devices with a larger gamut can represent more colors. Similarly, gamut may also refer to the colors within a defined color space, which is not linked to a specific device. A trichromatic gamut is often visualized as a color triangle. A less common usage defines gamut as the subset of colors contained within an image, scene or video.
This is an index of color topic-related articles.
Colorfulness, chroma and saturation are attributes of perceived color relating to chromatic intensity. As defined formally by the International Commission on Illumination (CIE) they respectively describe three different aspects of chromatic intensity, but the terms are often used loosely and interchangeably in contexts where these aspects are not clearly distinguished. The precise meanings of the terms vary by what other functions they are dependent on.
A spectral color is a color that is evoked by monochromatic light, i.e. either a spectral line with a single wavelength or frequency of light in the visible spectrum, or a relatively narrow spectral band. Every wave of visible light is perceived as a spectral color; when viewed as a continuous spectrum, these colors are seen as the familiar rainbow. Non-spectral colors are evoked by a combination of spectral colors.
A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components. When this model is associated with a precise description of how the components are to be interpreted, taking account of visual perception, the resulting set of colors is called "color space."
A color solid is the three-dimensional representation of a color space or model and can be thought as an analog of, for example, the one-dimensional color wheel, which depicts the variable of hue ; or the two-dimensional chromaticity diagram, which depicts the variables of hue and colorfulness. The added spatial dimension allows a color solid to depict the three dimensions of color: lightness, hue, and colorfulness, allowing the solid to depict all conceivable colors in an organized three-dimensional structure.
Lightness is a visual perception of the luminance of an object. It is often judged relative to a similarly lit object. In colorimetry and color appearance models, lightness is a prediction of how an illuminated color will appear to a standard observer. While luminance is a linear measurement of light, lightness is a linear prediction of the human perception of that light.
In colorimetry, the CIE 1976L*, u*, v*color space, commonly known by its abbreviation CIELUV, is a color space adopted by the International Commission on Illumination (CIE) in 1976, as a simple-to-compute transformation of the 1931 CIE XYZ color space, but which attempted perceptual uniformity. It is extensively used for applications such as computer graphics which deal with colored lights. Although additive mixtures of different colored lights will fall on a line in CIELUV's uniform chromaticity diagram, such additive mixtures will not, contrary to popular belief, fall along a line in the CIELUV color space unless the mixtures are constant in lightness.
In color science, color difference or color distance is the separation between two colors. This metric allows quantified examination of a notion that formerly could only be described with adjectives. Quantification of these properties is of great importance to those whose work is color-critical. Common definitions make use of the Euclidean distance in a device-independent color space.
A color space is a specific organization of colors. In combination with color profiling supported by various physical devices, it supports reproducible representations of color – whether such representation entails an analog or a digital representation. A color space may be arbitrary, i.e. with physically realized colors assigned to a set of physical color swatches with corresponding assigned color names, or structured with mathematical rigor. A "color space" is a useful conceptual tool for understanding the color capabilities of a particular device or digital file. When trying to reproduce color on another device, color spaces can show whether shadow/highlight detail and color saturation can be retained, and by how much either will be compromised.
Varieties of the color yellow may differ in hue, chroma or lightness, or in two or three of these qualities. Variations in value are also called tints and shades, a tint being a yellow or other hue mixed with white, a shade being mixed with black. A large selection of these various colors is shown below.
A color appearance model (CAM) is a mathematical model that seeks to describe the perceptual aspects of human color vision, i.e. viewing conditions under which the appearance of a color does not tally with the corresponding physical measurement of the stimulus source.
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. 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. Some conflicting definitions of the terms are:
In colorimetry, the HSLuvcolor space is a human-friendly alternative to the HSL color space. It was formerly known as "husl". It is a variation of the CIE LCH(uv) color space, where the C (colorfulness) component is replaced by a "Saturation" (S) component representing the colorfulness percentage relative to the maximum sRGB can provide given the L and H values. The value has nothing to do with "saturation" in color theory.
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