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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 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 (e.g., additive, subtractive) that reflects the physics of how light interacts with physical media, and ultimately the retina. The most common color mixing models are the additive primary colors (red, green, blue) and the subtractive primary colors (cyan, magenta, yellow).

Primary colors can also be conceptual (not necessarily real), either as additive mathematical elements of a color space or as irreducible phenomenological categories in domains such as psychology and philosophy. Color space primaries are precisely defined and empirically rooted in psychophysical colorimetry experiments which are foundational for understanding color vision. Primaries of some color spaces are complete (that is, all visible colors are described in terms of their primaries weighted by nonnegative primary intensity coefficients) but necessarily imaginary (that is, there is no plausible way that those primary colors could be represented physically, or perceived). Phenomenological accounts of primary colors, such as the psychological primaries, have been used as the conceptual basis for practical color applications even though they are not a quantitative description in and of themselves.

Sets of color space primaries are generally arbitrary, in the sense that there is no one set of primaries that can be considered the canonical set. 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.

The concept of primary colors has a long, complex history. The choice of primary colors has changed over time in different domains that study color. Descriptions of primary colors come from areas including philosophy, art history, color order systems, and scientific work involving the physics of light and perception of color.

Art education materials commonly use red, yellow, and blue as primary colors, sometimes suggesting that they can mix all colors. No set of real colorants or lights can mix all possible colors, however. In physics, the three primary colors are typically red, green and blue, after the different types of photoreceptor pigments in the cone cells.

Color model primaries
A color model is an abstract model intended to describe the ways that colors behave, especially in color mixing. Most color models are defined by the interaction of multiple primary colors. Since most humans are trichromatic, color models that want to reproduce a meaningful portion of a human's perceptual gamut must use at least three primaries. More than three primaries are allowed, for example, to increase the size of the gamut of the color space, but the entire human perceptual gamut can be reproduced with just three primaries (albeit imaginary ones as in the CIE XYZ color space).

Some humans (and most mammals ) are dichromats, corresponding to specific forms of color blindness in which color vision is mediated by only two of the types of color receptors. Dichromats require only two primaries to reproduce their entire gamut and their participation in color matching experiments was essential in the determination of cone fundamentals leading to all modern color spaces. Despite most vertebrates being tetrachromatic, and therefore requiring four primaries to reproduce their entire gamut, there is only one scholarly report of a functional human tetrachromat, for which trichromatic color models are insufficient.

Additive models

The perception elicited by multiple light sources co-stimulating the same area of the retina is additive, i.e., predicted via summing the spectral power distributions (the intensity of each wavelength) of the individual light sources assuming a color matching context. For example, a purple spotlight on a dark background could be matched with coincident blue and red spotlights that are both dimmer than the purple spotlight. If the intensity of the purple spotlight was doubled it could be matched by doubling the intensities of both the red and blue spotlights that matched the original purple. The principles of additive color mixing are embodied in Grassmann's laws. Additive mixing is sometimes described as "additive color matching" to emphasize the fact the predictions based on additivity only apply assuming the color matching context. Additivity relies on assumptions of the color matching context such as the match being in the foveal field of view, under appropriate luminance, etc.

Additive mixing of coincident spot lights was applied in the experiments used to derive the CIE 1931 colorspace (see color space primaries section). The original monochromatic primaries of the wavelengths of 435.8 nm (violet), 546.1 nm (green), and 700 nm (red) were used in this application due to the convenience they afforded to the experimental work.

Small red, green, and blue elements (with controllable brightness) in electronic displays mix additively from an appropriate viewing distance to synthesize compelling colored images. This specific type of additive mixing is described as partitive mixing. Red, green, and blue light are popular primaries for partitive mixing since primary lights with those hues provide a large color triangle (gamut).

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. For example, in 1953 the NTSC specified primaries that were representative of the phosphors available in that era for color CRTs. Over decades, market pressures for brighter colors resulted in CRTs using primaries that deviated significantly from the original standard. Currently, ITU-R BT.709-5 primaries are typical for high-definition television.

Subtractive models

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. Each layer partially absorbs some wavelengths of light from the illumination while letting others pass through, resulting in a colored appearance. The resultant spectral power distribution is predicted by the wavelength-by-wavelength product of the spectral reflectance of the illumination and the product of the spectral reflectances of all of the layers. Overlapping layers of ink in printing mix subtractively over reflecting white paper, while the reflected light mixes in a partitive way to generate color images. Importantly, unlike additive mixture, the color of the mixture is not well predicted by the colors of the individual dyes or inks. 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). In general, using fewer inks as primaries results in more economical printing but using more may result in better color reproduction.

Cyan (C), magenta (M), and yellow (Y) are good chromatic subtractive primaries in that filters with those colors can be overlaid to yield a surprisingly large chromaticity gamut. A black (K) ink (from the older "key plate") is also used in CMYK systems to augment C, M and Y inks or dyes due to both being more efficient in terms of time and expense and less likely to introduce visible defects. Before the color names cyan and magenta were in common use, these primaries were often known as blue and red, respectively, and their exact color has changed over time with access to new pigments and technologies. Organizations such as Fogra, European Color Initiative and SWOP publish colorimetric CMYK standards for the printing industry.

Traditional red, yellow, and blue primary colors as a subtractive system

Color theorists since the seventeenth century, and many artists and designers since that time, have taken red, yellow, and blue to be the primary colors (see history below). This RYB system, in "traditional color theory", is often used to order and compare colors, and sometimes proposed as a system of mixing pigments to get a wide range of, or "all", colors. O'Connor describes the role of RYB primaries in traditional color theory: "A cornerstone component of traditional color theory, the RYB conceptual color model underpins the notion that the creation of an exhaustive gamut of color nuances occurs via intermixture of red, yellow, and blue pigments, especially when applied in conjunction with white and black pigment color. In the literature relating to traditional color theory and RYB color, red, yellow, and blue are often referred to as primary colors and represent exemplar hues rather than specific hues that are more pure, unique, or proprietary variants of these hues."

Traditional color theory is based on experience with pigments, more than on the science of light. In 1920, Snow and Froehlich explained: "It does not matter to the makers of dyes if, as the physicist says, red light and green light in mixture make yellow light, when they find by experiment that red pigment and green pigment in mixture produce gray. 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 published in 1961.

In discussing color design for the web, Jason Beaird writes: "The reason many digital artists still keep a red, yellow, and blue color wheel handy is because the color schemes and concepts of traditional color theory are based on that model. ... Even though I design mostly for the Web—a medium that's displayed in RGB—I still use red, yellow, and blue as the basis for my color selection. I believe that color combinations created using the red, yellow, and blue color wheel are more aesthetically pleasing, and that good design is about aesthetics."

Of course, the notion that all colors can be mixed from RYB primaries is not true, just as it is not true in any system of real primaries. For example, if the blue pigment is a deep Prussian blue, then a muddy desaturated green may be the best that can be had by mixing with yellow. To achieve a larger gamut of colors via mixing, the blue and red pigments used in illustrative materials such as the Color Mixing Guide in the image are often closer to peacock blue (a blue-green or cyan) and carmine (or crimson or magenta) respectively. Printers traditionally used inks of such colors, known as "process blue" and "process red", before modern color science and the printing industry converged on the process colors (and names) cyan and magenta (this is not to say that RYB is the same as CMY, or that it is exactly subtractive, but that there is a range of ways to conceptualize traditional RYB as a subtractive system in the framework of modern color science).

Faber-Castell identifies the following three colors: "Cadmium yellow" (number 107) for yellow, "Phthalo blue" (number 110) for blue and "Deep scarlet red" (number 219) for red, as the closest to primary colors for its Art & Graphic color pencils range. "Cadmium yellow" (number 107) for yellow, "Phthalo blue" (number 110) for blue and "Pale geranium lake" (number 121) for red, are provided as primary colors in its basic 5 color "Albrecht Dürer" watercolor marker set.

Mixing pigments in limited palettes

The first known use of red, yellow, and blue as "simple" or "primary" colors, by Chalcidius, ca. AD 300, was possibly based on the art of paint mixing.

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. Some writers and artists have found these schemes difficult to reconcile with the actual practice of painting. 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.

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. There is no consensus on a specific set of pigments that are considered primary colors – the choice of pigments depends entirely on the artist's subjective preference of subject and style of art, as well as material considerations like lightfastness and mixing behavior. A variety of limited palettes have been employed by artists for their work.

The color of light (i.e., the spectral power distribution) reflected from illuminated surfaces coated in paint mixes is not well approximated by a subtractive or additive mixing model. Color predictions that incorporate light scattering effects of pigment particles and paint layer thickness require approaches based on the Kubelka–Munk equations, but even such approaches are not expected to predict the color of paint mixtures precisely due to inherent limitations. Artists typically rely on mixing experience and "recipes" to mix desired colors from a small initial set of primaries and do not use mathematical modeling.

MacEvoy explains why artists often chose a palette closer to RYB than to CMY: "Because the 'optimal' pigments in practice produce unsatisfactory mixtures; because the alternative selections are less granulating, more transparent, and mix darker values; and because visual preferences have demanded relatively saturated yellow to red mixtures, obtained at the expense of relatively dull green and purple mixtures. Artists jettisoned 'theory' to obtain the best color mixtures in practice."

Color space primaries

A color space is a subset of a color model, where the primaries have been defined, either directly as photometric spectra, or indirectly as a function of other color spaces. For example, sRGB and Adobe RGB are both color spaces based on the RGB color model. However, the green primary of Adobe RGB is more saturated than the equivalent in sRGB, and therefore yields a larger gamut. Otherwise, choice of color space is largely arbitrary and depends on the utility to a specific application.

Imaginary primaries
Color space primaries are derived from canonical colorimetric experiments that represent a standardized model of an observer (i.e., a set of color matching functions) adopted by Commission Internationale de l'Eclairage (CIE) standards. The abbreviated account of color space primaries in this section is based on descriptions in Colorimetry - Understanding The CIE System.

The CIE 1931 standard observer is derived from experiments in which participants observing a foveal 2° bipartite field with a dark surround. Half of the field is illuminated with a monochromatic test stimulus (ranging from 380 nm to 780 nm) and the other half is the matching stimulus illuminated with three coincident monochromatic primary lights: 700 nm for red (R), 546.1 nm for green (G), and 435.8 nm for blue (B). These primaries correspond to CIE RGB color space. The intensities of the primary lights could be adjusted by the participant observer until the matching stimulus matched the test stimulus, as predicted by Grassman's laws of additive mixing. Different standard observers from other color matching experiments have been derived since 1931. The variations in experiments include choices of primary lights, field of view, number of participants etc. but the presentation below is representative of those results.

Matching was performed across many participants in incremental steps along the range of test stimulus wavelengths (380 nm to 780 nm) to ultimately yield the color matching functions: $$\overline{r}(\lambda)$$, $$\overline{g}(\lambda)$$ and $$\overline{b}(\lambda)$$ that represent the relative intensities of red, green, and blue light to match each wavelength ($$\lambda$$). These functions imply that $$[C]$$ units of the test stimulus with any spectral power distribution, $$P(\lambda)$$, can be matched by $[R]$, $[G]$, and $[B]$ units of each primary where:

Each integral term in the above equation is known as a tristimulus value and measures amounts in the adopted units. No set of real primary lights can match another monochromatic light under additive mixing so at least one of the color matching functions is negative for each wavelength. A negative tristimulus value corresponds to that primary being added to the test stimulus instead of the matching stimulus to achieve a match.

The negative tristimulus values made certain types of calculations difficult, so the CIE put forth new color matching functions $$\overline{x}(\lambda)$$, $$\overline{y}(\lambda)$$, and $$\overline{z}(\lambda)$$ defined by the following linear transformation:

These new color matching functions correspond to imaginary primary lights X, Y, and Z (CIE XYZ color space). All colors can be matched by finding the amounts $[X]$, $[Y]$, and $[Z]$ analogously to $[R]$, $[G]$, and $[B]$ as defined in $$. The functions $$\overline{x}(\lambda)$$, $$\overline{y}(\lambda)$$, and $$\overline{z}(\lambda)$$ based on the specifications that they should be nonnegative for all wavelengths, $$\overline{y}(\lambda)$$ be equal to photometric luminance, and that $$[X]=[Y]=[Z]$$ for an equienergy (i.e., a uniform spectral power distribution) test stimulus.

Derivations use the color matching functions, along with data from other experiments, to ultimately yield the cone fundamentals: $$\overline{l}(\lambda)$$, $$\overline{m}(\lambda)$$ and $$\overline{s}(\lambda)$$. 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. The three cone fundamentals are related to the original color matching functions by the following linear transformation (specific to a 10° field):

LMS color space comprises three primary lights (L, M, and S) that stimulate only the L-, M-, and S-cones respectively. A real primary that stimulates only the M-cone is impossible, and therefore these primaries are imaginary. The LMS color space has significant physiological relevance as these three photoreceptors mediate trichromatic color vision in humans.

Both XYZ and LMS color spaces are complete since all colors in the gamut of the standard observer are contained within their color spaces. Complete color spaces must have imaginary primaries, but color spaces with imaginary primaries are not necessarily complete (e.g. ProPhoto RGB color space).

Real primaries

Color spaces used in color reproduction must use real primaries that can be reproduced by practical sources, either lights in additive models, or pigments in subtractive models. Most RGB color spaces have real primaries, though some maintain imaginary primaries. For example, all the sRGB primaries fall within the gamut of human perception, and so can be easily represented by practical light sources, including CRT and LED displays, hence why sRGB is still the color space of choice for digital displays.

A color in a color space is defined as a combination of its primaries, where each primary must give a non-negative contribution. Any color space based on a finite number of real primaries is incomplete in that it cannot reproduce every color within the gamut of the standard observer.

Practical color spaces such as sRGB and scRGB are typically (at least partially) defined in terms of linear transformations from CIE XYZ, and color management often uses CIE XYZ as a middle point for transformations between two other color spaces.

Most color spaces in the color-matching context (those defined by their relationship to CIE XYZ) inherit its three-dimensionality. However, more complex color appearance models like CIECAM02 require extra dimensions to describe colors appear under different viewing conditions.

Psychological primaries

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. To Hering, the unique hues appeared as pure colors, while all others were "psychological mixes" of two of them. Furthermore, these colors were organized in "opponent" pairs, red vs. green and yellow vs. blue so that mixing could occur across pairs (e.g., a yellowish green or a yellowish red) but not within a pair (i.e., reddish green cannot be imagined). An achromatic opponent process along black and white is also part of Hering's explanation of color perception. Hering asserted that we did not know why these color relationships were true but knew that they were. Although there is a great deal of evidence for the opponent process in the form of neural mechanisms, there is currently no clear mapping of the psychological primaries to neural correlates.

The psychological primaries were applied by Richard S. Hunter as the primaries for Hunter L,a,b colorspace that led to the creation of CIELAB. The Natural Color System is also directly inspired by the psychological primaries.

Philosophy
Philosophical writing from ancient Greece has described notions of primary colors but they can be difficult to interpret in terms of modern color science. Theophrastus (c. 371–287 BCE) described Democritus' position that the primary colors were white, black, red, and green. In Classical Greece, Empedocles identified white, black, red, and, (depending on the interpretation) either yellow or green as primary colors. Aristotle described a notion in which white and black could be mixed in different ratios to yield chromatic colors; this idea had considerable influence in Western thinking about color. François d'Aguilon's notion of the five primary colors (white, yellow, red, blue, black) was influenced by Aristotle's idea of the chromatic colors being made of black and white. The 20th century philosopher Ludwig Wittgenstein explored color-related ideas using red, green, blue, and yellow as primary colors.

Light and color vision
Isaac Newton used the term "primary color" to describe the colored spectral components of sunlight. A number of color theorists did not agree with Newton's work. David Brewster advocated that red, yellow, and blue light could be combined into any spectral hue late into the 1840s. Thomas Young proposed red, green, and violet as the three primary colors, while James Clerk Maxwell favored changing violet to blue. Hermann von Helmholtz proposed "a slightly purplish red, a vegetation-green, slightly yellowish, and an ultramarine-blue" as a trio. Newton, Young, Maxwell, and Helmholtz were all prominent contributors to "modern color science" that ultimately described the perception of color in terms of the three types of retinal photoreceptors.

Colorants
John Gage's The Fortunes Of Apelles provides a summary of the history of primary colors as pigments in painting and describes the evolution of the idea as complex. Gage begins by describing Pliny the Elder's account of notable Greek painters who used four primaries. 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). Sil was historically confused as a blue pigment between the 16th and 17th centuries leading to claims about white, black, red, and blue being the fewest colors required for painting. Thomas Bardwell, an 18th century Norwich portrait painter, was skeptical of practical relevance of Pliny's account.

Robert Boyle, the Irish chemist, introduced the term primary color in English in 1664 and claimed that there were five primary colors (white, black, red, yellow, and blue). 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".

Red, yellow, and blue as primaries became a popular notion in the 18th and 19th centuries. 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. Moses Harris, an entomologist and engraver, also describes red, yellow, and blue as "primitive" colors in 1766. Léonor Mérimée described red, yellow, and blue in his book on painting (originally published in French in 1830) as the three simple/primitive colors that can make a "great variety" of tones and colors found in nature. George Field, a chemist, used the word primary to describe red, yellow, and blue in 1835. Michel Eugène Chevreul, also a chemist, discussed red, yellow, and blue as "primary" colors in 1839.

Color order systems

Historical perspectives on color order systems ("catalogs" of color) that were proposed in the 18th and 19th centuries describe them as using red, yellow, and blue pigments as chromatic primaries. Tobias Mayer (a German mathematician, physicist, and astronomer) described a triangular bipyramid with red, yellow and blue at the 3 vertices in the same plane, white at the top vertex, and black and the bottom vertex in a public lecture in 1758. There are 11 planes of colors between the white and black vertices inside the triangular bipyramid. Mayer did not seem to distinguish between colored light and colorant though he used vermilion, orpiment (King’s yellow), and Bergblau (azurite) in partially complete colorings of planes in his solid. Johann Heinrich Lambert (a Swiss mathematician, physicist, and astronomer) proposed a triangular pyramid with gamboge, carmine, and Prussian blue as primaries and only white at the top vertex (since Lambert could produce a mixture that was sufficiently black with those pigments). Lambert's work on this system was published in 1772. Philipp Otto Runge (the Romantic German painter) firmly believed in the theory of red, yellow and blue as the primary colors (again without distinguishing light color and colorant). His color sphere was ultimately described in an essay titled Farben-Kugel (color ball) published by Goethe in 1810. 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.

Red, yellow, and blue as primary colors
Numerous authors have taught that red, yellow, and blue (RYB) are the primary colors in art education materials since at least the 19th century, following the ideas tabulated above from earlier centuries.

A wide variety of contemporary educational sources also describe the RYB primaries. These sources range from children's books and art material manufacturers to painting and color guides. Art education materials often suggest that RYB primaries can be mixed to create all other colors.

Criticism
Albert Munsell, an American painter (and creator of the Munsell color system), referred to the notion of RYB primaries as "mischief", "a widely accepted error", and underspecified in his book A Color Notation, first published in 1905.

Itten's ideas about RYB primaries have been criticized as ignoring modern color science with demonstrations that some of Itten's claims about mixing RYB primaries are impossible.

title: Primary color


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Talk:Primary color

Color matching in figures
The cover image from King's book is nice. Like a lot of color plates, I am not so sure about the actual hues in the book. The cover red, yellow and blue look different than the scan. The archive scan doesn't look like cyan, magenta, yellow. Maneesh (talk) 17:20, 11 May 2021 (UTC)
 * This is as complicated & philosophical as the topic  :-).  The paper is not white in the archive image.  So is it a faithful vs. darkened reproduction of an aged book? And is an aged book more faithful than making it look like it did when it was printed?   :-) North8000 (talk) 17:36, 11 May 2021 (UTC)
 * My thought is that any renaming of hues over what is in the text is speculative. You would need a reliable source that compared hues in a credible/critical way to rename them in the caption. Maneesh (talk) 17:50, 11 May 2021 (UTC)
 * I think an image from the archive scan would make more sense to use here. These seem to be different editions or something (the archive copy's cover doesn't have the funny looking offset in the title lettering either). It's quite confusing to see text describe a color as red when the color looks like a magenta (while not the case on the cover). Maneesh (talk) 02:52, 14 May 2021 (UTC)
 * I think my scan is more accurate than the one on archive. I have the original, and it's definitely very close to what you'd call CMY, or printers' process colors.  Maneesh, I can loan you my copy if you'd like, since we're local to each other. The cover is indeed a bit weird; I don't know if it's printed on the colored background, or the background color is also printed.  It looks like the paper is brown (since it's also brown on the back), and the inks are thick enough to mostly cover that. That brown is rendered too reddish in my scan, but the "red" and "blue" really do look pretty close to "magenta" and "cyan" (the plates, more so than the cover); not that we have to say that in the caption, just my impression.  I suppose it's also possible that the 1923 and 1925 versions are different; different publisher, and distinctly different cover colorations. Dicklyon (talk) 04:43, 14 May 2021 (UTC)
 * Thank you for the kind offer but I trust you are seeing the colors correctly. I would still say it makes sense to use the archive scan since it doesn't show such an obvious visual conflict (on such core idea in this article), but as I said in the other thread, I won't do any serious editing here for awhile. I'll let other editors make their suggestions. Maneesh (talk) 06:59, 14 May 2021 (UTC)
 * I have no opinion. Since the use here is the the concept presented by the book author, possibly whatever reproduction is the closest to what the author of the book intended would be best. North8000 (talk) 11:34, 14 May 2021 (UTC)
 * The trouble with the archive scans, including from Google Books, is that they typically don't have a realistic gamma, which makes the colors dark and over-saturated. In terms of "what the author intended", it seems clear to me that he intended to use primaries that have a decent gamut, which means his blue is more like printer's "process blue" or "cyan blue" as it has been called, and his red similarly what printers call "process red", which is closer to magenta. The names and the colors don't quite line up the way we use them in modern color science, but they are what they are. Dicklyon (talk) 19:11, 14 May 2021 (UTC)
 * I found an old book that talks about "process blue" and variants. I've clipped a bit of a color image from p.295 showing one case of their process red and blue, and adjust the curve by dragging the "center" thingie in Photoshop Levels command to 2, to approximately correct for the fact that the Google Book Search puts linear intensity data, instead of gamma compressed, into the page images.  This lightens the colors and shifts them toward cyan and magenta.  Try it. Dicklyon (talk) 22:50, 14 May 2021 (UTC)
 * Any of these inferences may be true, but I think it is much easier to explain by crappy color proofing. It's easy to believe this was a 'sell me' color book and no one was paying particular attention at press time. The book itself covers "red" and "magenta" pigments inside, I don't think the visual association with those pigments was different in 192X as compared to now. The claims on page 8 about mixing all colors aren't even interpretable or easily reconciled with the cover or color plate: "With the following colors at hand all known colors may be obtained. Lemon yellow, which is of greenish hue; yellow of orange hue; red with orange hue; red which has a bluish cast. Blue with a reddish tone, also blue with a leaning to- ward green. A liberal supply of white and some black which does not contain blue.". A fun artifact from the times, I presume not cited by anyone and I don't think it the claims about color should be taken too seriously. Maneesh (talk) 23:28, 16 May 2021 (UTC)
 * It seems sensible to me that they mention the use of 6 pigments (2 each of RYB, leaning different directions) to get "all known colors". It's a pretty large gamut at least.  Not sure what your point is about "crappy color proofing".  In my experience, printers are pretty careful about getting things right.  The color of the archive scans can't be trusted though.  Dicklyon (talk) 03:30, 21 June 2021 (UTC)
 * I never suggested that using 6 pigments is unreasonable to make a painting or that the gamut wouldn't be sufficiently for some purposes requiring diverse gamuts. The source is not coherent, red, yellow and blue (not white and black) are suggested to mix *all known colors* on the cover with the three circles, they are the primary colors on the color plate (does that mean they mix all known colors? who knows?). Then there are eight colors specified in the prose to mix "all known colors". The colors you can't mix with those colors are exactly the chromatic red, yellow, and blue single pigments. Then again, it's basically impossible to evaluate the claims because the specifications are imprecise (what is "blue with a reddish tone?"...alizarin? manganese violet?). Is this the "RYB system"? How can "yellow of greenish hue" and "blue with a leaning toward green" be a part of the "RYB system". Not the least bit suspicious about his prescription given the book isn't much more than a list of pigments? Just old silly color think meant to sell silly color books. Munsell was obviously familiar with this type of thing before this book was published. Color proofing mistakes aren't that common but this wouldn't surprise me at all (the offset on the cover title is certainly suspicious). We can speculate on what underlying differences that you see in your copy and the edition from a different year on archive but they aren't obvious and they don't appear to be consistent even within the edition (cover vs. color plate vs. prose). If your copy was printed in 1920 something, I'd bet very strongly that there must some shifts in color over the course of a century. Best to avoid such incoherent sources. Maneesh (talk) 05:18, 21 June 2021 (UTC)
 * And I never suggested that the source is particularly "coherent" in the sense that you mean. But it is a representation of some of the thinking in traditional color theory, and some of the practice for getting a decent gamut size.  I get that you think traditional color theory is "just old silly color think"; that's one POV on the relation between traditional color theory and modern color science.  But traditional color theory is still going strong 100 years later, because there's another POV about how useful the RYB circle arrangement is to artists and designers.  Still unsure what you think is relevant about color differences in different editions and scans of this book though. Dicklyon (talk) 17:06, 21 June 2021 (UTC)
 * If a source doesn't make coherent claims and not notable what sense is there in putting in this article? Itten doesn't make much sense, but he is notable. It's not clear what the color plate in the book is saying, you've added "To achieve a larger gamut of colors via mixing, the red and blue pigments used in illustrative materials such as the Color Mixing Guide in the image are often closer to peacock blue (a blue-green or cyan) and carmine (color) (or crimson or magenta), respectively." How do you know what inks were used in that book? Are those the inks we are seeing in the color plate? Have they decayed over about a century? The color plate says red, yellow, and blue...that magenta circle sure doesn't look red to me and the book knows the difference between magenta and red pigments since it lists them separately. Unnecessary confusion. Your sectioning has also put the broad general claims about primary colors in pigments that span a thousand years *under* "Traditional red, yellow, and blue primary colors" which is used to describe 18th century ideas; this is isn't sensible. Maneesh (talk) 17:51, 22 June 2021 (UTC)
 * Notability is not a concept that's applicable to sources. As for coherent claims, it seems coherent enough to me; just not from the POV of modern color science; but that's not where it's coming from.  As for the colors of the inks, I listed several sources from back around them that discuss the colors of the process-red and process-blue inks typically used, and this book seems to fit that. Dicklyon (talk) 01:48, 23 June 2021 (UTC)
 * Indeed, notability isn't the correct complaint, WP:UBO is. Not coherent to me because it makes a variety of claims that aren't consistent with eachother, the most clear one in the prose is precisely *not* "RYB", so it doesn't make sense to describe that in a section which you have titled "Traditional red, yellow, and blue primary colors". You do not know the identity of the inks without some sort of chemical analysis. Perhaps it was some sort of custom run, a number of inks were available at the time. The claim in the article that suggests the colors of the inks used is pure and unnecessary speculation. Maneesh (talk) 17:45, 24 June 2021 (UTC)

I got hold of the 1923 edition and scanned them together. The coverstock is a very different color, so let's ignore that. And they have different publishers, in different states. So the fact that there's a little bit of color variation makes sense. Still, both use a "process red" not far from magenta, and a "process blue" not far from cyan. For what that's worth. Dicklyon (talk) 04:31, 2 July 2021 (UTC)
 * I have no idea what ink or inks the color plates use. I don't know how you could claim to know either without a mass spec and some other tools. The text says "red" and apparently the color plates are more purple and the cover doesn't match with those claims. The color plate makes claims about mixing a single chart with a small number of colors. The actual content of the book says something completely different with respect to mixing all known colors - the part that is actually relevant to this article. None of this is coherent, none of this is used by others it should not be used here. Maneesh (talk) 21:37, 2 July 2021 (UTC)
 * Maybe if you two experts could state exactly what the content question/debate is, this 1/2 dummy (me) could chime in on it. :-) Sincerely, North8000 (talk) 00:10, 3 July 2021 (UTC)
 * I have no idea what the question is, or why Maneesh thinks I'm making claims about what inks were used when I say something about what color they are. He previously seemed to be saying that my observations on the 1925 edition were due to sloppy printing, and that the 1923 edition colors were probably closer to the modern interpretation of red and blue.  This scans suggests to me that that's not the case.  I'll loan him the books if he wants to use his own eyes, or his own colorimeter, or his own mass spectrometer, to find a way to say something other than what a lot of sources say about process red and process blue printing inks. Dicklyon (talk) 05:21, 3 July 2021 (UTC)
 * The claim in the article is "To achieve a larger gamut of colors via mixing, the red and blue pigments used in illustrative materials such as the Color Mixing Guide in the image are often closer to peacock blue (a blue-green or cyan) and carmine (color) (or crimson or magenta), respectively."....so the inks used to print the image on the page from "Color Mixing" were closer to peacock blue, carmine...whether you are describing the appearance of the primary inks or their chemical composition, how do you know the composition of the ink that you see? You can't unless someone tells you directly or you do a detailed chemical analysis. The appearance of a layer ink to your eye doesn't tell you what inks were mixed to make that layer, in general, there are many ways of making a given color of ink on a page from different primary inks. Furthermore, how does one know that this was "often" the case since in the same source we see what common sense would tell us about the practice in that era, that "many variations are encountered...practice of artists in changing the various colors makes standardization of process colors impossible". The inclusion of this book is even more confusing since it says that the primary colors are red, yellow and blue but the red definitely has some blue in it, which is different from what the cover clearly suggests...which is different than what the prose says (which uses white and black and colors that are exactly not red, yellow and blue). What is this source doing here and why is there so many unnecessary, and unsupported inferences?Maneesh (talk) 05:32, 3 July 2021 (UTC)
 * Maneesh, on your "what is this source doing here" question, whether it's from a "be a useful article" standpoint, or a wiki guidelines, IMO there is a low bar for inclusion of a source. The wiki source standards are essentially sourcing and sourcing requirements for  inclusion of material.  Now with that sidebar aside, I think that most of your comments are basically saying that there is material in there that doesn't seem to have a basis.  Which means that it also doesn't meet the higher bar of being sourced.     If so there are many things that you could do. You could just try boldly editing it to remove whatever you think is wrong.  You could just put  tags on the items that you are concerned about. Or you could propose specific changes/deletions here in talk.  Sincerely, North8000 (talk) 17:11, 3 July 2021 (UTC)
 * No that isn't what I am saying. I am well aware that it makes sense to include some incoherent sources that say nothing more "RYB are the primary colors", you can see I've added a number of those sources myself to show how the claim is common. It's the additional, reachy unsupported inferences that are being made about how the color plates in "Color Mixing" that are the problem in this specific instance. There needs to be a consensus that the claim around "To achieve a larger gamut of colors via mixing, the red and blue pigments used in illustrative materials such as the Color Mixing Guide..." can't be true since no one here knows what pigments were used to make the color plates in that source. Maneesh (talk) 17:19, 3 July 2021 (UTC)
 * And that it doesn't make sense to show the pages of a source that says red yellow and blue are the primary colors when the image seems to be showing magenta/purple. That is very very confusing to readers, you don't need to show a picture from a source that isn't making sense about such a basic claim. Maneesh (talk) 17:22, 3 July 2021 (UTC)
 * The statement is about the pigment colors, not the pigment chemistry. I cited various sources about process red and process blue colors in support of the observation.  I use this source because it has the best illustration I could find of how the process colors mix on paper.  It makes a bridge between the paint mixing that it talks about and the color printing arts in which the RYB conceptual model had to actually work for mixing a wide gamut of colors, which evolved eventually to the CMYK model.  Dicklyon (talk) 17:46, 3 July 2021 (UTC)
 * You don't know the appearance or the chemical identity of inks that was used to print that color plate. You don't know if those colors are single ink or a mix, what they look like or what they are. You just see a layer of color, that's all, that doesn't tell you what it is made of. We know that there were a variety of inks in use at the time, and there is no obvious way to find out what they were here without something like mass spectrometry; I doubt anyone would take up that study in this case.  Plain and simple. Maneesh (talk) 22:24, 3 July 2021 (UTC)
 * Yes, we agree that I don't know the chemical identity of the inks used. Dicklyon (talk) 23:57, 3 July 2021 (UTC)
 * Don't know how much more obvious I can make your speculation, what I said "You don't know the appearance or the chemical identity of inks that was used to print that color plate.", you reply with "we agree that I don't know the chemical identity of the inks used". You can only see appearance of their subtractive mixture. Maneesh (talk) 00:34, 4 July 2021 (UTC)

Here's what the text currently says: Printers traditionally used inks of such colors, known as "process blue" and "process red", before modern color science and the printing industry converged on the process colors (and names) cyan and magenta (this is not to say that RYB is the same as CMY, or that it is exactly subtractive, but that there is a range of ways to conceptualize traditional RYB as a subtractive system in the framework of modern color science).
 * To achieve a larger gamut of colors via mixing, the red and blue pigments used in illustrative materials such as the Color Mixing Guide in the image are often closer to peacock blue (a blue-green or cyan) and carmine (color) (or crimson or magenta), respectively.

Please let us know what part of this you find unsupported or whatever. Maybe I should have said "carmine lake" and "crimson lake", like the sources, instead of "carmine" and "crimson"? Is that a difference? Dicklyon (talk) 00:03, 4 July 2021 (UTC)

Oh, I see, carmine lake and crimson lake in the sources are names for the pigment carmine, while I'm talking about the color of the ink being somewhere between red and magnenta, like the color of those pigments. Not a big jump, and pretty consistent with what the sources are saying. Where it says "process red may be considered carmine lake", I think it's using the pigment name to convey a pretty accurate description of the color, not saying that's the actual pigment used usually for process red. Dicklyon (talk) 00:21, 4 July 2021 (UTC)
 * For emphasis again: "You don't know the appearance or the chemical identity of inks that was used to print that color plate." You can only see appearance of their subtractive mixture. Maneesh (talk) 00:34, 4 July 2021 (UTC)
 * Are you saying that maybe the red and yellow and blue circles were not printed with the red and yellow and blue process inks, but with mixtures? I suppose that's possible.  Seems unlikely though.  Dicklyon (talk) 03:27, 4 July 2021 (UTC)
 * Your eyes do not have magic powers. You cannot tell by looking at spot of color on a page what inks were used to make that color. Maneesh (talk) 04:20, 4 July 2021 (UTC)
 * But maybe my eyes have a sufficiently advanced technology that you can't distinguish from magic? Anyway, if your speculation is right, then the printing inks would have a wider gamut than the mixtures of the shown red, yellow, and blue, right?  Is that your point?  What of it?  Dicklyon (talk) 04:55, 4 July 2021 (UTC)
 * And by mixing do you mean printing by halftoning? Or do you mean they mixed their process inks from other inks?  I should be able to look and see if there's any halftoning; I didn't see any, but I'll check in a few days when I get back home from my Independence Day holiday weekend. Dicklyon (talk) 05:02, 4 July 2021 (UTC)
 * I've made my point clear to the point of pain at this point. You are speculating on the identity of inks that no reliable source tells you about (not even the text that the diagram is from which is little more than a list of colorants that includes such inks) or ever will. I'm not the one who is speculating here, it is you who are making claims about the appearance and/or identities of the inks used to print a colored page. The speculation should be removed from the article, the diagram should also be removed as it only serves to only confuse since the text says red but the hue shown is purple/magenta. I am also not interested in your WP:OR on what process was used to print that page. Maneesh (talk) 05:07, 4 July 2021 (UTC)
 * No, I have no interest in the identities of the inks; just their colors. I don't think I'm speculating when I say that books about color were printed with 3-color and 4-color printing processes, as described in the sources I cited. Dicklyon (talk) 05:23, 4 July 2021 (UTC)
 * You are absolutely speculating because the process, chemical identity and appearance of the inks used to print that page are no known to you or anyone at this point, nor are they written down in that book. No source will tell you what process was used to print the color plates in that book. You cannot tell me if those colors are single pigments or mixes or which pigments they are. The only way you could is via some sort of chemical analysis. Maneesh (talk) 20:52, 5 July 2021 (UTC)
 * I have no interest in, and make no claims about, what pigments might have gone into the inks. Dicklyon (talk) 21:48, 5 July 2021 (UTC)

Color/Colour
I think that it doesn't matter which spelling we choose, as long as it's consistent within the article. However, according to the talk page this article is in American English, the title uses the American spelling and if you search for both spellings in the article, the American one is the most used. I see no reason to use the British spelling. If no one has any objections, I say we should just change the whole article to American English. Wikifan153 (talk) 09:04, 12 August 2022 (UTC)
 * I see you did this already, thanks. Curran919 (talk) 11:23, 24 September 2022 (UTC)

Short description
@Utter Donkey a short description is intended to be scanned quickly in order to distinguish it from similarly-titled articles. It is not intended to replace the lead sentence. A category usually suffices. From the linked page: "Editors should keep in mind that short descriptions are meant to distinguish an article from similarly named articles in search results, and not to define the subject."

Right now the short description reads as "Sets of colors that can be mixed to produce gamut of c...". Doing a search for "Primary color", the other results have the following short descriptions: "1998 American film", "1996 book by Joe Klein", "2004 studio album by Day After Tomorrow"

There is probably a short description that fits in with these more terse examples. Since you seem engaged I will trust your decision. Cheers Wizmut (talk) 16:07, 28 April 2024 (UTC)

 * I think a compromise is necessary between the two. The current is too wordy and yours is too short to be accurate. Lets workshop it. Considering that the article is primary color, perhaps: "a fundamental color in color mixing". Curran919 (talk) 07:56, 2 May 2024 (UTC)
 * Sounds good to me, without the "a". Wizmut (talk) 02:49, 3 May 2024 (UTC)

Article subsection cleanup?
I wanted to suggest the 2 separate sections on the RYB model be merged into one.

At the moment, it’s confusing having a second RYB subsection under history. I’d suggest combining the two and moving it under “Subtractive models”. I’m not sure why it’s a higher level section outside of subtractive models (I assume it happened as a result of the earlier RYB debate and just never got resolved) but it makes much more sense to add it under that subsection.

Leaving the Criticism portion as a subsection under the relocated RYB model section would be fine I think, or making it an additional subsection under Subtractive models? (Could be renamed “controversy” or “debate on subtractive models within art”?) I read a great article on this topic from an artistic perspective a couple years ago (discussing the benefits of using a CMY model in art vs. RYB) but unfortunately I don’t remember if I bookmarked it. I’ll drop it here if I can find it again.

I’d try to handle this stuff myself but I don’t trust my ability to write things clearly and concisely and health issues prevent me from taking on any additional projects right now (especially since there appears to be some disagreement on this article which may lead to further debate). Catfrost (talk) 00:18, 9 May 2024 (UTC)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Talk:Primary color