A color model is an abstract mathematical model describing the way
color
Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are assoc ...
s 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 (viewing conditions, etc.), taking account of
visual perception
Visual perception is the ability to interpret the surrounding Biophysical environment, environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the ...
, the resulting set of colors is called "
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 colorwhether such representation entails an analog or a digital represen ...
."
This article describes ways in which human
color vision can be modeled, and discusses some of the models in common use.
Tristimulus color space
![gamut full](https://upload.wikimedia.org/wikipedia/commons/1/1e/Gamut_full.png)
One can picture this space as a region in three-dimensional
Euclidean space
Euclidean space is the fundamental space of geometry, intended to represent physical space. Originally, that is, in Euclid's ''Elements'', it was the three-dimensional space of Euclidean geometry, but in modern mathematics there are Euclidean ...
if one identifies the ''x'', ''y'', and ''z'' axes with the stimuli for the long-wavelength (''L''), medium-wavelength (''M''), and short-wavelength (''S'')
light receptors. The origin, (''S'',''M'',''L'') = (0,0,0), corresponds to black. White has no definite position in this diagram; rather it is defined according to the
color temperature
Color temperature is the color of light emitted by an idealized opaque, non-reflective body at a particular temperature measured in kelvins. The color temperature scale is used to categorize the color of light emitted by other light sources ...
or white balance as desired or as available from ambient lighting. The human color space is a horse-shoe-shaped cone such as shown here (see also
CIE chromaticity diagram
The CIE 1931 color spaces are the first defined quantitative links between distributions of wavelengths in the electromagnetic visible spectrum, and physiologically perceived colors in human color vision. The mathematical relationships that defi ...
below), extending from the origin to, in principle, infinity. In practice, the human color receptors will be saturated or even be damaged at extremely high light intensities, but such behavior is not part of the
CIE color space and neither is the changing color perception at low light levels (see:
Kruithof curve
The Kruithof curve describes a region of illuminance levels and color temperatures that are often viewed as comfortable or pleasing to an observer. The curve was constructed from psychophysical data collected by Dutch physicist Arie Andries K ...
).
The most saturated colors are located at the outer rim of the region, with brighter colors farther removed from the origin. As far as the responses of the receptors in the eye are concerned, there is no such thing as "brown" or "gray" light. The latter color names refer to orange and white light respectively, with an intensity that is lower than the light from surrounding areas. One can observe this by watching the screen of an
overhead projector
An overhead projector (often abbreviated to OHP), like a film or slide projector, uses light to project an enlarged image on a screen, allowing the view of a small document or picture to be shared with a large audience.
In the overhead projec ...
during a meeting: one sees black lettering on a white background, even though the "black" has in fact not become darker than the white screen on which it is projected before the projector was turned on. The "black" areas have not actually become darker but appear "black" relative to the higher intensity "white" projected onto the screen around it. See also
color constancy
Color constancy is an example of subjective constancy and a feature of the human color perception system which ensures that the perceived color of objects remains relatively constant under varying illumination conditions. A green apple ...
.
The human tristimulus space has the property that additive mixing of colors corresponds to the adding of vectors in this space. This makes it easy to, for example, describe the possible colors (
gamut
In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain ''complete subset'' of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circ ...
) that can be constructed from the red, green, and blue primaries in a computer display.
CIE XYZ color space
One of the first mathematically defined color spaces is the CIE XYZ color space (also known as CIE 1931 color space), created by the
International Commission on Illumination
The International Commission on Illumination (usually abbreviated CIE for its French name, Commission internationale de l'éclairage) is the international authority on light, illumination, colour, and colour spaces. It was established in 1913 a ...
in 1931. These data were measured for human observers and a 2-degree field of view. In 1964, supplemental data for a 10-degree field of view were published.
Note that the tabulated sensitivity curves have a certain amount of arbitrariness in them. The shapes of the individual X, Y and Z sensitivity curves can be measured with a reasonable accuracy. However, the overall
luminosity function
A luminous efficiency function or luminosity function represents the average spectral sensitivity of human visual perception of light. It is based on subjective judgements of which of a pair of different-colored lights is brighter, to descri ...
(which in fact is a weighted sum of these three curves) is subjective, since it involves asking a test person whether two light sources have the same brightness, even if they are in completely different colors. Along the same lines, the relative magnitudes of the X, Y, and Z curves are arbitrarily chosen to produce equal areas under the curves. One could as well define a valid color space with an X sensitivity curve that has twice the amplitude. This new color space would have a different shape. The sensitivity curves in the CIE 1931 and 1964 xyz color space are scaled to have equal areas under the curves.
Sometimes XYZ colors are represented by the luminance, Y, and chromaticity coordinates ''x'' and ''y'', defined by:
:
and
Mathematically, ''x'' and ''y'' are projective coordinates and the colors of the chromaticity diagram occupy a region of the
real projective plane
In mathematics, the real projective plane is an example of a compact non-orientable two-dimensional manifold; in other words, a one-sided surface. It cannot be embedded in standard three-dimensional space without intersecting itself. It has b ...
. Because the CIE sensitivity curves have equal areas under the curves, light with a flat energy spectrum corresponds to the point (''x'',''y'') = (0.333,0.333).
The values for ''X'', ''Y'', and ''Z'' are obtained by integrating the product of the spectrum of a light beam and the published color-matching functions.
Additive and subtractive color models
RYB color model
RGB color model
![RGBCube a](https://upload.wikimedia.org/wikipedia/commons/b/b4/RGBCube_a.svg)
Media that transmit light (such as television) use
additive color
Additive color or additive mixing is a property of a color model that predicts the appearance of colors made by coincident component lights, i.e. the perceived color can be predicted by summing the numeric representations of the component colo ...
mixing with
primary color
A set of primary colors or primary colours (see spelling differences) consists of colorants or colored lights that can be mixed in varying amounts to produce a gamut of colors. This is the essential method used to create the perception of a ...
s of
red
Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondar ...
,
green
Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combi ...
, and
blue
Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when ...
, each of which stimulates one of the three types of the eye's color receptors with as little stimulation as possible of the other two. This is called "
RGB
The RGB color model is an additive color model in which the red, green and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three addi ...
" color space. Mixtures of light of these primary colors cover a large part of the human color space and thus produce a large part of human color experiences. This is why
color television sets or color computer monitors need only produce mixtures of red, green and blue light. See
Additive color
Additive color or additive mixing is a property of a color model that predicts the appearance of colors made by coincident component lights, i.e. the perceived color can be predicted by summing the numeric representations of the component colo ...
.
Other primary colors could in principle be used, but with red, green and blue the largest portion of the
human color space
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, an ...
can be captured. Unfortunately there is no exact consensus as to what loci in the
chromaticity diagram
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 ...
the red, green, and blue colors should have, so the same RGB values can give rise to slightly different colors on different screens.
CMY and CMYK color models
It is possible to achieve a large range of colors seen by humans by combining
cyan,
magenta
Magenta () is a color that is variously defined as pinkish- purplish- red, reddish-purplish-pink or mauvish-crimson. On color wheels of the RGB (additive) and CMY (subtractive) color models, it is located exactly midway between red and blu ...
, and
yellow
Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the ...
transparent dyes/inks on a white substrate. These are the ''
subtractive''
primary color
A set of primary colors or primary colours (see spelling differences) consists of colorants or colored lights that can be mixed in varying amounts to produce a gamut of colors. This is the essential method used to create the perception of a ...
s. Often a fourth ink,
black
Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white ...
, is added to improve reproduction of some dark colors. This is called the "CMY" or "CMYK" color space.
The cyan ink absorbs red light but reflects green and blue, the magenta ink absorbs green light but reflects red and blue, and the yellow ink absorbs blue light but reflects red and green. The white substrate reflects the transmitted light back to the viewer. Because in practice the CMY inks suitable for printing also reflect a little bit of color, making a deep and neutral black impossible, the K (black ink) component, usually printed last, is needed to compensate for their deficiencies. Use of a separate black ink is also economically driven when a lot of black content is expected, e.g. in text media, to reduce simultaneous use of the three colored inks. The dyes used in traditional color photographic prints and
slides are much more perfectly transparent, so a K component is normally not needed or used in those media.
Cylindrical-coordinate color models
A number of color models exist in which colors are fit into
conic
In mathematics, a conic section, quadratic curve or conic is a curve obtained as the intersection of the surface of a cone with a plane. The three types of conic section are the hyperbola, the parabola, and the ellipse; the circle is a specia ...
,
cylindrical or
spherical
A sphere () is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. A sphere is the set of points that are all at the same distance from a given point in three-dimensional space.. That given point is the ce ...
shapes, with neutrals running from black to white along a central axis, and hues corresponding to angles around the perimeter. Arrangements of this type date back to the 18th century, and continue to be developed in the most modern and scientific models.
Background
Different color theorists have each designed unique
color solid
A color solid is the three-dimensional representation of a color model, an analog of the two-dimensional color wheel. The added spatial dimension allows a color solid to depict an added dimension of color variation. Whereas a two-dimensional ...
s. Many are in the shape of a
sphere
A sphere () is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. A sphere is the set of points that are all at the same distance from a given point in three-dimensional space.. That given point is th ...
, whereas others are warped three-dimensional ellipsoid figures—these variations being designed to express some aspect of the relationship of the colors more clearly. The color spheres conceived by
Phillip Otto Runge and
Johannes Itten
Johannes Itten (11 November 1888 – 25 March 1967) was a Swiss expressionist painter, designer, teacher, writer and theorist associated with the Bauhaus (''Staatliches Bauhaus'') school. Together with German-American painter Lyonel Feining ...
are typical examples and prototypes for many other color solid schematics. The models of Runge and Itten are basically identical, and form the basis for the description below.
Pure, saturated hues of equal brightness are located around the equator at the periphery of the color sphere. As in the color wheel,
contrasting (or complementary) hues are located opposite each other. Moving toward the center of the color sphere on the equatorial plane, colors become less and less saturated, until all colors meet at the central
axis
An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to:
Mathematics
* Axis of rotation: see rotation around a fixed axis
* Axis (mathematics), a designator for a Cartesian-coordinat ...
as a neutral
gray
Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed o ...
. Moving vertically in the color sphere, colors become lighter (toward the top) and darker (toward the bottom). At the upper pole, all hues meet in white; at the bottom pole, all hues meet in black.
The vertical axis of the color sphere, then, is gray all along its length, varying from
black
Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white ...
at the bottom to
white
White is the lightest color and is achromatic (having no hue). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully reflect and scatter all the visible wavelengths of light. White o ...
at the top. All pure (saturated) hues are located on the surface of the sphere, varying from light to dark down the color sphere. All impure (unsaturated hues, created by mixing contrasting colors) comprise the sphere's interior, likewise varying in brightness from top to bottom.
HSL and HSV
HSL and HSV are both cylindrical geometries, with hue, their angular dimension, starting at the
red
Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondar ...
primary at 0°, passing through the
green
Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combi ...
primary at 120° and the
blue
Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when ...
primary at 240°, and then wrapping back to red at 360°. In each geometry, the central vertical axis comprises the ''neutral'', ''achromatic'', or ''gray'' colors, ranging from black at lightness 0 or value 0, the bottom, to white at lightness 1 or value 1, the top.
Most televisions, computer displays, and projectors produce colors by combining red, green, and blue light in varying intensities—the so-called
RGB
The RGB color model is an additive color model in which the red, green and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three addi ...
additive
Additive may refer to:
Mathematics
* Additive function, a function in number theory
* Additive map, a function that preserves the addition operation
* Additive set-functionn see Sigma additivity
* Additive category, a preadditive category with f ...
primary color
A set of primary colors or primary colours (see spelling differences) consists of colorants or colored lights that can be mixed in varying amounts to produce a gamut of colors. This is the essential method used to create the perception of a ...
s. However, the relationship between the constituent amounts of red, green, and blue light and the resulting color is unintuitive, especially for inexperienced users, and for users familiar with
subtractive color
Subtractive color or subtractive color mixing predicts the spectral power distribution of light after it passes through successive layers of partially absorbing media. This idealized model is the essential principle of how dyes and inks are use ...
mixing of paints or traditional artists’ models based on tints and shades.
In an attempt to accommodate more traditional and intuitive color mixing models, computer graphics pioneers at
PARC and
NYIT
The New York Institute of Technology (NYIT or New York Tech) is a private research university founded in 1955. It has two main campuses in New York—one in Old Westbury, on Long Island, and one in Manhattan. Additionally, it has a cybersecur ...
developed the HSV model in the mid-1970s, formally described by
Alvy Ray Smith[ Smith (1978)] in the August 1978 issue of
''Computer Graphics''. In the same issue, Joblove and Greenberg
[ Joblove and Greenberg (1978)] described the HSL model—whose dimensions they labeled ''hue'', ''relative chroma'', and ''intensity''—and compared it to HSV. Their model was based more upon how colors are organized and conceptualized in
human vision
Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflec ...
in terms of other color-making attributes, such as hue, lightness, and chroma; as well as upon traditional color mixing methods—e.g., in painting—that involve mixing brightly colored pigments with black or white to achieve lighter, darker, or less colorful colors.
The following year, 1979, at
SIGGRAPH,
Tektronix
Tektronix, Inc., historically widely known as Tek, is an American company best known for manufacturing test and measurement devices such as oscilloscopes, logic analyzers, and video and mobile test protocol equipment.
Originally an independent ...
introduced graphics terminals using HSL for color designation, and the Computer Graphics Standards Committee recommended it in their annual status report. These models were useful not only because they were more intuitive than raw RGB values, but also because the conversions to and from RGB were extremely fast to compute: they could run in real time on the hardware of the 1970s. Consequently, these models and similar ones have become ubiquitous throughout image editing and graphics software since then.
Munsell color system
Another influential older cylindrical color model is the early-20th-century
Munsell color system
In colorimetry, the Munsell color system is a color space that specifies colors based on three properties of color: hue (basic color), chroma (color intensity), and value (lightness). It was created by Professor Albert H. Munsell in the firs ...
.
Albert Munsell
Albert Henry Munsell (January 6, 1858 – June 28, 1918) was an American painter, teacher of art, and the inventor of the Munsell color system.
He was born in Boston, Massachusetts, attended and served on the faculty of Massachusetts Normal Art ...
began with a spherical arrangement in his 1905 book ''A Color Notation'', but he wished to properly separate color-making attributes into separate dimensions, which he called ''hue'', ''value'', and ''chroma'', and after taking careful measurements of perceptual responses, he realized that no symmetrical shape would do, so he reorganized his system into a lumpy blob.
Munsell's system became extremely popular, the de facto reference for American color standards—used not only for specifying the color of paints and crayons, but also, e.g., electrical wire, beer, and soil color—because it was organized based on perceptual measurements, specified colors via an easily learned and systematic triple of numbers, because the color chips sold in the ''Munsell Book of Color'' covered a wide
gamut
In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain ''complete subset'' of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circ ...
and remained stable over time (rather than fading), and because it was effectively marketed by
Munsell's Company. In the 1940s, the
Optical Society of America
Optica (formerly known as The Optical Society (OSA) and before that as the Optical Society of America) is a professional society of individuals and companies with an interest in optics and photonics. It publishes journals and organizes conference ...
made extensive measurements, and adjusted the arrangement of Munsell colors, issuing a set of "renotations". The trouble with the Munsell system for computer graphics applications is that its colors are not specified via any set of simple equations, but only via its foundational measurements: effectively a
lookup table. Converting from requires interpolating between that table's entries, and is extremely computationally expensive in comparison with converting from or which only requires a few simple arithmetic operations.
[ Fairchild (2005)]
Natural Color System
The Swedish Natural Color System (NCS), widely used in Europe, takes a similar approach to the Ostwald bicone at right. Because it attempts to fit color into a familiarly shaped solid based on "
phenomenological" instead of photometric or psychological characteristics, it suffers from some of the same disadvantages as HSL and HSV: in particular, its lightness dimension differs from perceived lightness, because it forces colorful yellow, red, green, and blue into a plane.
[ MacEvoy (2010)]
Preucil hue circle
In
densitometry
Densitometry is the quantitative measurement of optical density in light-sensitive materials, such as photographic paper or photographic film, due to exposure to light.
Overview
Optical density is a result of the darkness of a developed picture ...
, a model quite similar to the hue defined above is used for describing colors of
CMYK process inks. In 1953, Frank Preucil developed two geometric arrangements of hue, the "Preucil hue circle" and the "Preucil hue hexagon", analogous to our ''H'' and ''H''
2, respectively, but defined relative to idealized cyan, yellow, and magenta ink colors. The "Preucil ''hue error''" of an ink indicates the difference in the "hue circle" between its color and the hue of the corresponding idealized ink color. The ''grayness'' of an ink is , where ''m'' and ''M'' are the minimum and maximum among the amounts of idealized cyan, magenta, and yellow in a density measurement.
CIELCHuv and CIELCHab
The
International Commission on Illumination
The International Commission on Illumination (usually abbreviated CIE for its French name, Commission internationale de l'éclairage) is the international authority on light, illumination, colour, and colour spaces. It was established in 1913 a ...
(CIE) developed the
XYZ model
XYZ may refer to: Music
* XYZ (American band), hard rock band
** ''XYZ'' (XYZ album), 1989 debut album
* ''XYZ'' (Andy Summers album), a 1987 solo album by Andy Summers
* ''XYZ'' (Gloo album), the 2019 debut album by English group Gloo
* XYZ (En ...
for describing the colors of light spectra in 1931, but its goal was to match human visual
metamerism, rather than to be perceptually uniform, geometrically. In the 1960s and 1970s, attempts were made to transform XYZ colors into a more relevant geometry, influenced by the Munsell system. These efforts culminated in the 1976
CIELUV and
CIELAB models. The dimensions of these models— and , respectively—are cartesian, based on the
opponent process
The opponent process is a color theory that states that the human visual system interprets information about color by processing signals from photoreceptor cells in an antagonistic manner. The opponent-process theory suggests that there are th ...
theory of color, but both are also often described using polar coordinates— and , respectively—where ''L''* is lightness, ''C''* is chroma, and ''h''* is hue angle. Officially, both CIELAB and CIELUV were created for their
color difference metrics ∆''E''*
''ab'' and ∆''E''*
''uv'', particularly for use defining color tolerances, but both have become widely used as color order systems and color appearance models, including in computer graphics and computer vision. For example,
gamut mapping
In digital imaging systems, color management (or colour management) is the controlled conversion between the color representations of various devices, such as image scanners, digital cameras, monitors, TV screens, film printers, computer printe ...
in
ICC color management
In digital imaging systems, color management (or colour management) is the controlled conversion between the color representations of various devices, such as image scanners, digital cameras, monitors, TV screens, film printers, computer printer ...
is usually performed in CIELAB space, and Adobe Photoshop includes a CIELAB mode for editing images. CIELAB and CIELUV geometries are much more perceptually relevant than many others such as RGB, HSL, HSV, YUV/YIQ/YCbCr or XYZ, but are not perceptually perfect, and in particular have trouble adapting to unusual lighting conditions.
[ Kuehni (2003)][Steven K. Shevell (2003) ''The Science of Color''. 2nd ed. Elsevier Science & Technology. . https://books.google.com/books?id=G1TC1uXb7awC&pg=PA201 ]
The HCL color space
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 ...
seems to be synonymous with CIELCH.
CIECAM02
The CIE's most recent model, CIECAM02
In colorimetry, CIECAM02 is the color appearance model published in 2002 by the International Commission on Illumination (CIE) Technical Committee 8-01 (''Color Appearance Modelling for Color Management Systems'') and the successor of CIECAM97s ...
(CAM stands for "color appearance model"), is more theoretically sophisticated and computationally complex than earlier models. Its aims are to fix several of the problems with models such as CIELAB and CIELUV, and to explain not only responses in carefully controlled experimental environments, but also to model the color appearance of real-world scenes. Its dimensions ''J'' (lightness), ''C'' (chroma), and ''h'' (hue) define a polar-coordinate geometry.[
]
Color systems
There are various types of color systems that classify color and analyse their effects. The American Munsell color system
In colorimetry, the Munsell color system is a color space that specifies colors based on three properties of color: hue (basic color), chroma (color intensity), and value (lightness). It was created by Professor Albert H. Munsell in the firs ...
devised by Albert H. Munsell is a famous classification that organises various colors into a color solid based on hue, saturation and value. Other important color systems include the Swedish Natural Color System
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 ...
(NCS), the Optical Society of America
Optica (formerly known as The Optical Society (OSA) and before that as the Optical Society of America) is a professional society of individuals and companies with an interest in optics and photonics. It publishes journals and organizes conference ...
's Uniform Color Space
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 o ...
(OSA-UCS), and the Hungarian Coloroid
The Coloroid Color System is a color space developed between 1962 and 1980 by Prof. Antal Nemcsics at the Budapest University of Technology and Economics for use by "architects and visual constructors". Since August 2000, the Coloroid has been ...
system developed by Antal Nemcsics Antal may refer to:
* Andal, 8th-century poet saint of South India
* Antal (given name)
* Antal (surname)
* 6717 Antal, a minor planet
See also
* Andal (disambiguation)
{{Disambiguation ...
from the Budapest University of Technology and Economics
The Budapest University of Technology and Economics ( hu, Budapesti Műszaki és Gazdaságtudományi Egyetem or in short ), official abbreviation BME, is the most significant university of technology in Hungary and is considered the world's olde ...
. Of those, the NCS is based on the opponent-process color model, while the Munsell, the OSA-UCS and the Coloroid attempt to model color uniformity. The American Pantone
Pantone LLC (stylized as PANTONE) is a limited liability company headquartered in Carlstadt, New Jersey. The company is best known for its Pantone Matching System (PMS), a proprietary color space used in a variety of industries, notably graphi ...
and the German RAL commercial color-matching systems differ from the previous ones in that their color spaces are not based on an underlying color model.
Other uses of "color model"
Models of mechanism of color vision
We also use "color model" to indicate a model or mechanism of color vision for explaining how color signals are processed from visual cones to ganglion cells. For simplicity, we call these models color mechanism models. The classical color mechanism models are Young
Young may refer to:
* Offspring, the product of reproduction of a new organism produced by one or more parents
* Youth, the time of life when one is young, often meaning the time between childhood and adulthood
Music
* The Young, an American roc ...
– Helmholtz's trichromatic model and Hering's opponent-process model. Though these two theories were initially thought to be at odds, it later came to be understood that the mechanisms responsible for color opponency receive signals from the three types of cones and process them at a more complex level.[Kandel ER, Schwartz JH and Jessell TM, 2000. ''Principles of Neural Science'', 4th ed., McGraw-Hill, New York. pp. 577–80.] A widely accepted model is called the zone model. A symmetrical zone model compatible with the trichromatic theory, the opponent theory, and Smith's color transform model is called the decoding model [Lu C, 2021, Explaining colour vision with the decoding model, Research Features, Vol.135, pp.142-145. ]
Vertebrate evolution of color vision
Vertebrate animals were primitively tetrachromatic. They possessed four types of cones—long, mid, short wavelength cones, and ultraviolet sensitive cones. Today, fish, amphibians, reptiles and birds are all tetrachromatic. Placental mammals lost both the mid and short wavelength cones. Thus, most mammals do not have complex color vision—they are dichromatic but they are sensitive to ultraviolet light, though they cannot see its colors. Human trichromatic color vision is a recent evolutionary novelty that first evolved in the common ancestor of the Old World Primates. Our trichromatic color vision evolved by duplication of the long wavelength sensitive opsin
Animal opsins are G-protein-coupled receptors and a group of proteins made light-sensitive via a chromophore, typically retinal. When bound to retinal, opsins become Retinylidene proteins, but are usually still called opsins regardless. Most ...
, found on the X chromosome. One of these copies evolved to be sensitive to green light and constitutes our mid wavelength opsin. At the same time, our short wavelength opsin evolved from the ultraviolet opsin of our vertebrate and mammalian ancestors.
Human red-green color blindness
Color blindness or color vision deficiency (CVD) is the decreased ability to see color or differences in color. It can impair tasks such as selecting ripe fruit, choosing clothing, and reading traffic lights. Color blindness may make some aca ...
occurs because the two copies of the red and green opsin genes remain in close proximity on the X chromosome. Because of frequent recombination during meiosis, these gene pairs can get easily rearranged, creating versions of the genes that do not have distinct spectral sensitivities.
See also
* Color appearance model
*Comparison of color models in computer graphics
This article provides introductory information about the RGB, HSV, and HSL color models from a computer graphics (Web page, image) perspective. An introduction to colors is also provided to support the main discussion.
Basics of color
Primary c ...
*RGBW color model RGBW may refer to:
Red, green, blue and white
* RGBW sensor, a color filter array
* RGBW, an LED strip light with four channels
* RGBW color wheel, in a DLP projector
* PenTile RGBW, in the PenTile matrix family
* RGBW sub-pixels, in WhiteMagic di ...
* RGBY color model
Notes
References
Bibliography
* This book doesn't discuss HSL or HSV specifically, but is one of the most readable and precise resources about current color science.
* Joblove and Greenberg's paper was the first describing the HSL model, which it compares to HSV.
* This book only briefly mentions HSL and HSV, but is a comprehensive description of color order systems through history.
* This paper explains how both HSL and HSV, as well as other similar models, can be thought of as specific variants of a more general "GLHS" model. Levkowitz and Herman provide pseudocode for converting from RGB to GLHS and back.
* . Especially the sections abou
"Modern Color Models"
an
MacEvoy's extensive site about color science and paint mixing is one of the best resources on the web. On this page, he explains the color-making attributes, and the general goals and history of color order systems—including HSL and HSV—and their practical relevance to painters.
* This is the original paper describing the "hexcone" model, HSV. Smith was a researcher at NYIT
The New York Institute of Technology (NYIT or New York Tech) is a private research university founded in 1955. It has two main campuses in New York—one in Old Westbury, on Long Island, and one in Manhattan. Additionally, it has a cybersecur ...
’s Computer Graphics Lab. He describes HSV's use in an early digital painting
Digital painting is an established art medium that typically combines a computer, a graphics tablet, and software of choice. The artist uses painting and drawing with the stylus that comes with the graphics tablet to create 2D paintings within ...
program.
External links
Illustrations and summaries of RGB, CMYK, LAB, HSV, HSL, and NCS
HSV Colors
by Hector Zenil, The Wolfram Demonstrations Project
The Wolfram Demonstrations Project is an organized, open-source collection of small (or medium-size) interactive programs called Demonstrations, which are meant to visually and interactively represent ideas from a range of fields. It is hos ...
.
HSV to RGB
by CodeBeautify.
{{Color topics
Model
A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a measure.
Models c ...
Mathematical modeling
*
Color vision