# Hue

An image with the hues cyclically shifted in HSL space.
The hues in the image of this Painted Bunting are cyclically rotated with time.
Hue is one of the three main attributes of perceived color, in addition to lightness and chroma (or colorfulness). Hue is also one of the three dimensions in some colorspaces along with saturation, and brightness (also known as lightness or value). Hue is that aspect of a color described with names such as "red", "yellow", etc.

Usually, colors with the same hue are distinguished with adjectives referring to their lightness and/or saturation, such as with "light blue", "pastel blue", "vivid blue". Notable exceptions include brown, which is a dark orange,[1] and pink, a light desaturated red.

In painting color theory, a hue refers to a pure color—one without tint or shade (added white or black pigment, respectively). A hue is an element of the color wheel.

## Computing hue

In opponent color spaces, such as CIE L*a*b* (CIELAB) and CIE L*u*v* (CIELUV), hue may be computed together with saturation (or chroma) by converting a color's chromaticity coordinates from rectangular coordinates into polar coordinates. Hue is the angular component of the polar representation, while chroma is the radial component.

Specifically, in CIELAB:[2]

while, analogously, in CIELUV:[2]

In practice, a four-quadrant arctangent may be used if available to invert these formulae.

### Computing hue from RGB

Preucil[3] describes a color hexagon, similar to a trilinear plot described by Evans, Hanson, and Brewer,[4] which may be used to compute hue. To place red at 0°, green at 120°, and blue at 240°, one may solve:

He also used a polar plot, which he termed a color circle.[3] Using R, G, and B, rather than the R, G, and B densities Preucil used, one may compute hue angle using the following scheme: determine which of the six possible orderings of R, G, and B prevail, then apply the appropriate formula; see table below.

Ordering Hue Region Formula
Red-Yellow
Yellow-Green
Green-Cyan
Cyan-Blue
Blue-Magenta
Magenta-Red

Note that in each case the formula contains the fraction , where H is the highest of R, G, and B; L is the lowest, and M is the mid one between the other two. This is referred to as the Preucil Hue Error, and was used in the computation of mask strength in photomechanical color reproduction.[5]

Hue angles computed for the Preucil circle agree with the hue angle computed for the Preucil Hexagon at integer multiples of 30 degrees (red, yellow, green, cyan, blue, magenta, and the colors mid-way between contiguous pairs), and differ by approximately 1.2 degrees at odd integer multiples of 15 degrees (based on the circle formula), the maximum divergence between the two.

#### Computing hue from RGB for HSB, HSV, and HSL color spaces

HSV color space as a conical object

The process of converting an RGB color into an HSL color space or HSV color space is usually based on a 6-piece or 12-piece piecewise-linear mapping, treating the HSV cone as a hexacone, or the HSL double cone as a double hexacone.[6]

## Specialized hues

The hues exhibited by caramel colorings and beers are fairly limited in range. The Linner hue index is used to quantify the hue of such products.

## Hue as a qualification in the names of artist's colors

Manufacturers of pigments use the word hue e.g. 'Cadmium Yellow (hue)' to indicate that the original pigmentation ingredient, often toxic, has been replaced by safer (or cheaper) alternatives whilst retaining the hue of the original. Replacements are often used for chromium, cadmium and alizarin.

## Hue vs. dominant wavelength

Dominant wavelength (or sometimes equivalent wavelength) is a physical analog to the perceptual attribute hue. On a chromaticity diagram, a line is drawn from a white point through the coordinates of the color in question, until it intersects the spectral locus. The wavelength at which the line intersects the spectrum locus is identified as the color's dominant wavelength if the point is on the same side of the white point as the spectral locus, and as the color's complementary wavelength if the point is on the opposite side.[7]

## References

1. ^ C J Bartleson, "Brown". Color Research and Application, 1 : 4, p 181-191 (1976).
2. ^ Colorimetry, second edition: CIE Publication 15.2. Vienna: Bureau Central of the CIE, 1986.
3. ^ Frank Preucil, "Color Hue and Ink Transfer … Their Relation to Perfect Reproduction, TAGA Proceedings, p 102-110 (1953).
4. ^ Ralph Merrill Evans, W T Hanson, and W Lyle Brewer, Principles of Color Photography. New York: Wiley, 1953
5. ^ Miles Southworth, Color Separation Techniques, second edition. Livonia, New York: Graphic Arts Publishing, 1979
6. ^ Max K. Agoston (2004). Computer Graphics and Geometric Modelling v. 1: Implementation and Algorithms. Springer, 301–304. ISBN 1852338180.
7. ^ Deane B Judd and Günter Wyszecki, Color in Business, Science, and Industry. New York: Wiley, 1976.

Color or colour[1] (see spelling differences) is the visual perceptual property corresponding in humans to the categories called red, yellow, blue, black, etc.
Lightness is a property of a color, or a dimension of a color space, that correlates with how bright or luminous a color is. In terms of the Lab color space, lightness is defined in a way to reflect the subjective brightness perception of a color for humans.
colorfulness, chroma, and saturation are related concepts referring to the intensity of a specific color. More technically, colorfulness is the perceived difference between the color of some stimulus and gray, chroma
Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 625–750 nm.
Yellow is the color evoked by light that stimulates both the L and M (long- and medium-wavelength) cone cells of the retina about equally, but does not significantly stimulate the S
colorfulness, chroma, and saturation are related concepts referring to the intensity of a specific color. More technically, colorfulness is the perceived difference between the color of some stimulus and gray, chroma
Brown, when used as a general term, is a color which is a dark yellow, orange, or red, of low luminance relative to lighter or white colored objects.[1]

Some pale orange and yellow colors of lower saturation are called light browns.
orange occurs between red and yellow in the visible spectrum at a wavelength of about 585 – 620 nm, and has a hue of 30° in HSV colour space. The complementary colour of orange is azure, a slightly greenish blue.
additional references or sources for verification.
* It may need a complete rewrite to meet Wikipedia's quality standards.

Painting, meant literally, is the practice of applying color to a surface (support) such as paper, canvas, wood, glass, lacquer or concrete. However, when used in an artistic sense, the term "painting" means the use of this activity in combination with drawing, composition and
Color Theory is the musical alter ego of American singer-keyboardist-songwriter Brian Hazard.

## Biography

Hazard, the sole member of Color Theory, began studying the piano at the relatively late age of thirteen.
tint is the mixture of a color with white (also called a pastel color) , and a shade is the mixture of a color with black. Mixing with white increases lightness, while mixing with black reduces it.
pigment is a material that changes the color of light it reflects as the result of selective color absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which the material itself emits light.
A color wheel (invented by Isaac Newton) is a wheel used to show the relations of colors. The standard color wheel for light has colors of magenta, yellow, and cyan located at positions that can form an equilateral triangle when connected by straight lines, and another for red,
opponent process is a color theory that states that the human visual system interprets information about color by processing signals from cones and rods in an antagonistic manner.
In colorimetry, the CIE 1976 (L*, u*, v*) color space, also known as the CIELUV color space, 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
Chromaticity is the quality of a color as determined by its purity and hue.[1]

"Purity" in this context, called "colorfulness" in CIECAM02, and "chroma" in Munsell, can be measured as the distance of a color from the neutral axis in a color space such as CIE
Cartesian coordinate system (also called rectangular coordinate system) is used to determine each point uniquely in a plane through two numbers, usually called the x-coordinate and the y-coordinate of the point.
polar coordinate system is a two-dimensional coordinate system in which each point on a plane is determined by an angle and a distance. The polar coordinate system is especially useful in situations where the relationship between two points is most easily expressed in terms of
RGB color model is an additive model in which red, green, and blue (often used in additive light models) are combined in various ways to reproduce other colors. The name of the model and the abbreviation ‘RGB’ come from the three primary colors, red, green, and blue and
Green is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520–570 nm. It is considered one of the additive primary colors.
The term blue may refer to any of a number of similar colours. The sensation of blue is made by light having a spectrum dominated by energy in the wavelength range of about 440–490 nm.
HSL and HSV (also called HSB) are two related representations of points in an RGB color space, which attempt to describe perceptual color relationships more accurately than RGB, while remaining computationally simple.
HSL and HSV (also called HSB) are two related representations of points in an RGB color space, which attempt to describe perceptual color relationships more accurately than RGB, while remaining computationally simple.

Caramel (IPA: /ˈkærəmɛl/, also
Beer is the world's oldest[1] and most popular[2][3] alcoholic beverage. It is produced by the fermentation of sugars derived from starch-based material — the most common being malted barley; however, wheat, corn, and rice are also widely
The Linner hue index,[1] , is used to describe the hues which a given caramel coloring may produce. In conjunction with tinctorial strength, or the depth of a caramel coloring's color, it describes the spectra which a solution of the coloring may produce at different
3, 2
(strongly acidic oxide)
Electronegativity 1.66 (Pauling scale)
Ionization energies
(more) 1st: 652.9 kJmol−1
2nd: 1590.6 kJmol−1
3rd: 2987 kJmol−1