Primary color

Primary pigments or light sources are selected for a given application on the basis of subjective preferences as well as practical factors such as cost, stability, availability etc.

In other domains, the three primary colors are typically red, green and blue, which are more closely aligned to the sensitivities of the photoreceptor pigments in the cone cells.

[12] Additive mixing of coincident spot lights was applied in the experiments used to derive the CIE 1931 colorspace (see color space primaries section).

[13] Small red, green, and blue elements (with controllable brightness) in electronic displays mix additively from an appropriate viewing distance to synthesize compelling colored images.

[14] The exact colors chosen for additive primaries are a compromise between the available technology (including considerations such as cost and power usage) and the need for large chromaticity gamut.

Over decades, market pressures for brighter colors resulted in CRTs using primaries that deviated significantly from the original standard.

[16] The subtractive color mixing model predicts the resultant spectral power distribution of light filtered through overlaid partially absorbing materials, usually in the context of an underlying reflective surface such as white paper.

[9]: 22–23 [17] Each layer partially absorbs some wavelengths of light from the illumination while letting others pass through, resulting in a colored appearance.

The typical number of inks in such a printing process is 3 (CMY) or 4 (CMYK), but can commonly range to 6 (e.g., Pantone hexachrome).

[23] Organizations such as Fogra,[24] European Color Initiative and SWOP publish colorimetric CMYK standards for the printing industry.

No matter what the spectroscope may demonstrate regarding the combination of yellow rays of light and blue rays of light, the fact remains that yellow pigment mixed with the blue pigment produces green pigment.The widespread adoption of teaching of RYB as primary colors in post-secondary art schools in the twentieth century has been attributed to the influence of the Bauhaus, where Johannes Itten developed his ideas on color during his time there in the 1920s, and of his book on color[30][31] published in 1961.

[38] Mixing pigments for the purpose of creating realistic paintings with diverse color gamuts is known to have been practiced at least since Ancient Greece (see history section).

The identity of a/the set of minimal pigments to mix diverse gamuts has long been the subject of speculation by theorists whose claims have changed over time, for example, Pliny's white, black, one or another red, and "sil", which might have been yellow or blue; Robert Boyle's white, black, red, yellow, and blue; and variations with more or fewer "primary" color or pigments.

[39]: 29–38  Nonetheless, it has long been known that limited palettes consisting of a small set of pigments are sufficient to mix a diverse gamut of colors.

[40][41][42][43][44] The set of pigments available to mix diverse gamuts of color (in various media such as oil, watercolor, acrylic, gouache, and pastel) is large and has changed throughout history.

The abbreviated account of color space primaries in this section is based on descriptions in Colorimetry - Understanding The CIE System.

The negative tristimulus values made certain types of calculations difficult, so the CIE put forth new color matching functions

These functions correspond to the response curves for the three types of color photoreceptors found in the human retina: long-wavelength (L), medium-wavelength (M), and short-wavelength (S) cones.

[68] The opponent process was proposed by Ewald Hering in which he described the four unique hues (later called psychological primaries in some contexts): red, green, yellow and blue.

Theophrastus (c. 371–287 BCE) described Democritus' position that the primary colors were white, black, red, and green.

[76]: 4  In Classical Greece, Empedocles identified white, black, red, and, (depending on the interpretation) either yellow or green as primary colors.

[76]: 87 The 20th century philosopher Ludwig Wittgenstein explored color-related ideas using red, green, blue, and yellow as primary colors.

David Brewster advocated that red, yellow, and blue light could be combined into any spectral hue late into the 1840s.

John Gage's The Fortunes Of Apelles provides a summary of the history of primary colors[39] as pigments in painting and describes the evolution of the idea as complex.

[87] Pliny distinguished the pigments (i.e., substances) from their apparent colors: white from Milos (ex albis), red from Sinope (ex rubris), Attic yellow (sil) and atramentum (ex nigris).

Thomas Bardwell, an 18th century Norwich portrait painter, was skeptical of the practical relevance of Pliny's account.

[40][89] The German painter Joachim von Sandrart eventually proposed removing white and black from the primaries and that one only needed red, yellow, blue, and green to paint "the whole creation".

Jacob Christoph Le Blon, an engraver, was the first to use separate plates for each color in mezzotint printmaking: yellow, red, and blue, plus black to add shades and contrast.

Le Blon used primitive in 1725 to describe red, yellow, and blue in a very similar sense as Boyle used primary.

[98]: 84  His spherical model of colors equally spaced red, yellow, and blue longitudinally with orange, green, and violet between them, and white and black at opposite poles.

The emission spectra of the three phosphors that define the additive primary colors of a CRT color video display. Other electronic color display technologies ( LCD , Plasma display , OLED ) have analogous sets of primaries with different emission spectra.
Additive primary color model
A photograph of the red, green, and blue elements (subpixels) of an LCD . Additive mixing explains how light from these colored elements can be used for photorealistic color image reproduction.
Subtractive primary color model
A magnified representation of small partially overlapping spots of cyan, magenta, yellow, and key (black) halftones in CMYK process printing. Each row represents the pattern of partially overlapping ink "rosettes" so that the patterns would be perceived as blue, green, and red when viewed on white paper from a typical viewing distance. The overlapping ink layers mix subtractively while additive mixing predicts the color appearance from the light reflected from the rosettes and white paper in between them.
Color Mixing Guide, John L. King 1925, cover and plates describing yellow, red, and blue color mixing
A representation of Johannes Itten 's color wheel showing his red, yellow, and blue as primary colors within the central equilateral triangle [ 26 ]
An 1896 self-portrait by Anders Zorn clearly showing a four-pigment palette of what are thought to be white, yellow ochre , vermillion , and black pigments [ 37 ]
A conceptual visualization of a color matching experiment. A circular foveal bipartite field (about the size one's thumbnail an arm's length away [ 56 ] ) is presented to the observer in a dark surround. One part of the field is illuminated by a monochromatic test stimulus. The participant adjusts the intensities of the three coincident monochromatic primary lights (which are usually red, green and blue hues) on either field until both the test stimulus and match stimulus appear as the exact same color. In this case the participant has added red to the 480 nm test stimulus and has almost matched the match stimulus made of only the green and blue lights of comparable intensities. The specific monochromatic primaries shown here are from the Stiles-Burch 1955 experiment. [ 57 ]
The CIE RGB , [ 58 ] [ 59 ] CIE XYZ [ 60 ] color matching functions and LMS cone fundamentals. [ 61 ] [ 62 ] The curves are all for 2° fields.
various RGB color spaces are represented as color triangles with vertices that represent the primaries. The 1931 CIE chromaticity diagram shows the gamut of the standard observer. Primaries outside of the colored region are imaginary.
Ewald Hering 's illustration [ 69 ] of the psychological primaries. Red/green and yellow/blue form opponent pairs (top). Each color can be psychologically mixed to make other colors (bottom) with both members of the other pair but not with its opponent according to Hering.
The color scheme of François d'Aguilon , where the two simple colors of white (albus) and black (niger) are mixed to the "noble" colors of yellow (flavus), red (rubeus), and blue (caeruleus). Orange (aureus), purple (purpureus), and green (viridis) are each combinations of two noble colors. [ 79 ]
Johann Heinrich Lambert 's "Farbenpyramide" tetrahedron published in 1772. Gamboge (yellow), carmine (red), and Prussian blue pigments are used the corner swatches of each "level" of lightness with mixtures filling the others and white at the top. [ 95 ]
Philipp Otto Runge 's sketch showing bl (blue), g (yellow) and r (red) as the fundamental colors [ 95 ] : 86