This article may be too technical for most readers to understand.(November 2023) |
The Color Naming System (CNS) is a systematic notation for named colors for computer applications using English terms created by Berk et al. in 1982. [1]
CNS uses ten color names, three of which (black, white, gray) are special, and has them combined or prefixed with several modifiers.
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The system expressed in Backus–Naur form looks something like this:. [2] [3]
named-color := gray-color | chromatic-color gray-color := 'black' | 'white' | lightness gray gray := 'gray' | 'grey' chromatic-color := [ tint | shade ] hue | [ lightness | saturation ]? hue tint := 'whitish' | 'pale' | 'brilliant' | 'vivid' shade := 'blackish' | 'dim' | 'deep' | 'vivid' saturation := 'grayish' | 'moderate' | 'strong' | 'vivid' lightness := 'moderate' | 'very'? [ 'dark' | 'light' ] hue := splash-color? base-color | base-color '-' base-color base-color := 'red' | 'orange' | 'brown' | 'yellow' | 'green' | 'blue' | 'purple' splash-color := 'reddish' | 'orangish' | 'brownish' | 'yellowish' | 'greenish' | 'bluish' | 'purplish'
There have been variations of the CNS proposed for inclusion into CSS that are more compatible with existing schemes. [4]
color := [saturation || lightness || transparency] hue saturation := absolute saturation-value | saturation-value relative saturation-value := 'dull' | 'bright' lightness := absolute lightness-value | lightness-value relative lightness-value := 'dark' | 'light' absolute := [modifier '-']? modifier := 'extra' | 'semi' relative := 'er' transparency := ['semi-']? opacity-value opacity-value := 'opaque' | 'transparent' hue := prime | general | special prime := 'red' | 'green' | 'blue' | 'cyan' | 'magenta' | 'yellow' | 'white' | 'black' general := 'navy' | 'lime' | 'teal' | 'aqua' | 'maroon' | 'purple' | 'fuchsia' | 'olive' | 'gray' | 'silver' special := extra | composite ; composite ≈ prime '-' prime extra := 'pink' | 'brown' | 'tan' | 'orange' composite := 'yellow-green' | 'green-cyan' | 'cyan-blue' | 'blue-magenta' | 'magenta-red' | …
ISCC-NBS System - a competing color naming system
The RGB colour 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 additive primary colors, red, green, and blue.
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.
HSL and HSV are alternative representations of the RGB color model, designed in the 1970s by computer graphics researchers. In these models, colors of each hue are arranged in a radial slice, around a central axis of neutral colors which ranges from black at the bottom to white at the top.
In computing, on the X Window System, X11 color names are represented in a simple text file, which maps certain strings to RGB color values. It was traditionally shipped with every X11 installation, hence the name, and is usually located in <X11root>/lib/X11/rgb.txt
. The web colors list is descended from it but differs for certain color names.
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 the visual arts, color theory is the body of practical guidance for color mixing and the visual effects of a specific color combination. Color terminology based on the color wheel and its geometry separates colors into primary color, secondary color, and tertiary color. The understanding of color theory dates to antiquity. Aristotle and Claudius Ptolemy already discussed which and how colors can be produced by mixing other colors. The influence of light on color was investigated and revealed further by al-Kindi and Ibn al-Haytham (d.1039). Ibn Sina, Nasir al-Din al-Tusi, and Robert Grosseteste discovered that contrary to the teachings of Aristotle, there are multiple color paths to get from black to white. More modern approaches to color theory principles can be found in the writings of Leone Battista Alberti and the notebooks of Leonardo da Vinci. A formalization of "color theory" began in the 18th century, initially within a partisan controversy over Isaac Newton's theory of color and the nature of primary colors. From there it developed as an independent artistic tradition with only superficial reference to colorimetry and vision science.
This is an index of color topic-related articles.
A color term is a word or phrase that refers to a specific color. The color term may refer to human perception of that color which is usually defined according to the Munsell color system, or to an underlying physical property. There are also numerical systems of color specification, referred to as color spaces.
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."
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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 color theory, a tint is a mixture of a color with white, which increases lightness, while a shade is a mixture with black, which increases darkness. Both processes affect the resulting color mixture's relative saturation. A tone is produced either by mixing a color with gray, or by both tinting and shading. Mixing a color with any neutral color reduces the chroma, or colorfulness, while the hue remains unchanged.
Varieties of the color red 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 red or other hue mixed with white, a shade being mixed with black. A large selection of these various colors are shown below.
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.
Blue Only mode is a special display mode on display units such as projectors and television sets whereby only the blue pixels or the blue cathode ray tube is used to generate the image.
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This article provides introductory information about the RGB, HSV, and HSL color models from a computer graphics perspective. An introduction to colors is also provided to support the main discussion.