The line of purples circled on the CIE chromaticity diagram
In color theory, the line of purples or purple boundary is the locus on the edge of the chromaticity diagram formed between extreme spectral red and violet. Except for these endpoints of the line, colors on the line are non-spectral (no monochromatic light source can generate them). Rather, every color on the line is a unique mixture in a ratio of fully saturated red and fully saturated violet, the two spectral color endpoints of visibility on the spectrum of pure hues. Colors on the line and spectral colors are the only ones that are fully saturated in the sense that, for any point on the line, no other possible color being a mixture of red and violet is more saturated than it.
Unlike spectral colors, which may be implemented, for example, by the nearly monochromatic light of a laser, with precision much finer than human chromaticity resolution, colors on the line are more difficult to depict. The sensitivity of each type of human cone cell to both spectral red and spectral violet, being at the opposite endpoints of the line and at the extremes of the visible spectrum, is very low. (See luminosity function.) Therefore, common purple colors are not highly bright.
The line of purples, a theoretical boundary of chromaticity, is distinct from "purples", a more general denomination of colors, which also refers to less than fully saturated colors (see shades of purple and shades of pink for examples) that form the interior of a triangle between white and the line of purples in the CIE chromaticity diagram.
In color spaces
In 3-dimensionalcolor spaces the line, if present, becomes a 2-dimensional shape. For example, in the CIE XYZ it is a planar sector bounded by black–red and black–violet rays. In systems premised on pigment colors, such as the Munsell and Pantone systems, boundary purples might be absent because the maximally possible lightness of a pigment vanishes when its chromaticity approaches the Line, such that purple pigments near the line are indistinguishable from black.
The RGB color model, although theoretically capable of approximating the colors of the line because it is an additive system, usually practically fails because of the limitations of the light source used. The boundary of sRGB (pictured) runs approximately parallel to the line, connecting the primaries red and (color wheel) blue, and thus purples near the line are absent from the gamut of sRGB. Magenta ink, which is one of CMYK's primaries, is also very distant from the line for the reason explained above. The wide-gamut RGB color space approximates the colors on the line better, but devices capable of displaying colors with this enhanced system are prohibitively expensive for ordinary consumers.
Table of highly saturated purples
Most of the names of the purple colors in the table below do not denominate colors on the line of purples, but instead are slightly less than maximally colorful, i.e. saturated.
Color or colour is the visual perception based on the electromagnetic spectrum. Though color is not an inherent property of matter, color perception is related to an object's light absorption, reflection, emission spectra and interference. For most humans, colors are perceived in the visible light spectrum with three types of cone cells (trichromacy). Other animals may have a different number of cone cell types or have eyes sensitive to different wavelength, such as bees that can distinguish ultraviolet, and thus have a different color sensitivity range. Animal perception of color originates from different light wavelength or spectral sensitivity in cone cell types, which is then processed by the brain.
A set of primary colors or primary colours 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 broad range of colors in, e.g., electronic displays, color printing, and paintings. Perceptions associated with a given combination of primary colors can be predicted by an appropriate mixing model that reflects the physics of how light interacts with physical media, and ultimately the retina.
Magenta is a purplish-red color. On color wheels of the RGB (additive) and CMY (subtractive) color models, it is located precisely midway between red and blue. It is one of the four colors of ink used in color printing by an inkjet printer, along with yellow, cyan, and black to make all the other colors. The tone of magenta used in printing, printer's magenta, is redder than the magenta of the RGB (additive) model, the former being closer to rose.
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.
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.
An RGB color space is one of many specific additive colorimetric color spaces based on the RGB color model.
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 that can be accurately represented in a given circumstance, such as within a given color space or by a certain output device.
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.
The RGB chromaticity space, two dimensions of the normalized RGB space, is a chromaticity space, a two-dimensional color space in which there is no intensity information.
A color wheel or color circle is an abstract illustrative organization of color hues around a circle, which shows the relationships between primary colors, secondary colors, tertiary colors etc.
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.
Red-violet refers to a rich color of high medium saturation about 3/4 of the way between red and magenta, closer to magenta than to red. In American English, this color term is sometimes used in color theory as one of the purple colors—a non-spectral color between red and violet that is a deep version of a color on the line of purples on the CIE chromaticity diagram.
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."
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 define these color spaces are essential tools for color management, important when dealing with color inks, illuminated displays, and recording devices such as digital cameras. The system was designed in 1931 by the "Commission Internationale de l'éclairage", known in English as the International Commission on Illumination.
A tertiary color or intermediate color is a color made by mixing one part of a primary color with half part of another primary, and none of any other primary color, in a given color space such as RGB, CMYK or RYB (traditional).
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.
Impossible colors are colors that do not appear in ordinary visual functioning. Different color theories suggest different hypothetical colors that humans are incapable of perceiving for one reason or another, and fictional colors are routinely created in popular culture. While some such colors have no basis in reality, phenomena such as cone cell fatigue enable colors to be perceived in certain circumstances that would not be otherwise.
Violet is a color term derived from the flower of the same name. There are numerous variations of the color violet, a sampling of which are shown below.
There are numerous variations of the color purple, a sampling of which is shown below.
DCI-P3 is an RGB color space first defined in 2005 as part of the Digital Cinema Initiative, to be used for digital theatrical motion picture distribution (DCDM). Display P3 is a variant developed by Apple Inc. for wide-gamut displays.
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