Color theory
Color theory, or more specifically traditional color theory, is a historical body of knowledge describing the behavior of colors — namely in color mixing, color contrast effects, color harmony, color schemes and color symbolism. Modern color theory is generally referred to as color science. While they both study color and its existence, modern or "traditional" color theory tends to be more subjective and have artistic applications, while color science tends to be more objective and have functional applications, such as in chemistry, astronomy or color reproduction. However, there is much intertwining between the two throughout history, and they tend to aid each other in their own evolutions.
Though, color theory can be considered a science unto itself that uses the relationship between human color perception and the interactions of colors together to build their palettes, schemes, and color mixes. Importantly, color theory relies upon objective standards in-order to be consistent in color mixing and presentation – i.e. to achieve the ideal color and effect, your ratios of colors must be consistent and often exact. As for functional applications, color theory, in tandem with color science, is what allows humans to achieve ideal camouflage, design paints that disperse more heat, and is often used by theme parks like Disney to achieve their ideal aesthetic.
Color theory dates back at least as far as Aristotle's treatise On Colors and Bharata's Nāṭya Shāstra. A formalization of "color theory" began in the 18th century, initially within a partisan controversy over Isaac Newton's theory of color, followed by what we considered to be "primary colors", continuing onward for centuries with multiple artists-turned-scientists, and vice versa, putting forth their own color wheels and color theories.
By the end of the 19th century, a schism had formed between color theory and color science due to the schism in humanities and traditional sciences, alongside the rise of Munsell color theory.
History
Color theory is rooted in antiquity, with early musings on color in Aristotle's On Colors and Ptolemy's Optics. The Nāṭya Shāstra composed in Ancient India, had an early, functional theory of color, considering four colours as primary, black, blue, yellow and red. It also describes the production of derived colors from primary colors.The influence of light on color was investigated and revealed further by al-Kindi and Ibn al-Haytham. 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.
Isaac Newton worked extensively on color theory, helping and developing his own theory from stating the fact that white light is composed of a spectrum of colors, and that color is not intrinsic to objects, but rather arises from the way an object reflects or absorbs different wavelengths. His 1672 paper on the nature of white light and colours forms the basis for all work that followed on colour and colour vision.
The RYB primary colors became the foundation of 18th-century theories of color vision, as the fundamental sensory qualities that are blended in the perception of all physical colors, and conversely, in the physical mixture of pigments or dyes. These theories were enhanced by 18th-century investigations of a variety of purely psychological color effects, in particular the contrast between "complementary" or opposing hues that are produced by color afterimages and in the contrasting shadows in colored light. These ideas and many personal color observations were summarized in two founding documents in color theory: the Theory of Colours by the German poet Johann Wolfgang von Goethe, and The Law of Simultaneous Color Contrast by the French industrial chemist Michel Eugène Chevreul. Charles Hayter published A New Practical Treatise on the Three Primitive Colours Assumed as a Perfect System of Rudimentary Information, in which he described how all colors could be obtained from just three.
Subsequently, German and English scientists established in the late 19th century that color perception is best described in terms of a different set of primary colors—red, green and blue-violet —modeled through the additive mixture of three monochromatic lights. Subsequent research anchored these primary colors in the differing responses to light by three types of color receptors or cones in the retina. On this basis the quantitative description of the color mixture or colorimetry developed in the early 20th century, along with a series of increasingly sophisticated models of color space and color perception, such as the opponent process theory.
Across the same period, industrial chemistry radically expanded the color range of lightfast synthetic pigments, allowing for substantially improved saturation in color mixtures of dyes, paints, and inks. It also created the dyes and chemical processes necessary for color photography. As a result, three-color printing became aesthetically and economically feasible in mass printed media, and the artists' color theory was adapted to primary colors most effective in inks or photographic dyes: cyan, magenta, and yellow. These CMY primary colors were reconciled with the RGB primaries, and subtractive color mixing with additive color mixing, by defining the CMY primaries as substances that absorbed only one of the retinal primary colors: cyan absorbs only red, magenta only green, and yellow only blue-violet. It is important to add that the CMYK, or process, color printing is meant as an economical way of producing a wide range of colors for printing, but is deficient in reproducing certain colors, notably orange and slightly deficient in reproducing purples. A wider range of colors can be obtained with the addition of other colors to the printing process, such as in Pantone's Hexachrome printing ink system, among others.
For much of the 19th century artistic color theory either lagged behind scientific understanding or was augmented by science books written for the lay public, in particular Modern Chromatics by the American physicist Ogden Rood, and early color atlases developed by Albert Munsell and Wilhelm Ostwald. Major advances were made in the early 20th century by artists teaching or associated with the German Bauhaus, in particular Wassily Kandinsky, Johannes Itten, Faber Birren and Josef Albers, whose writings mix speculation with an empirical or demonstration-based study of color design principles.
Color mixing
One of the earliest purposes of color theory was to establish rules governing the mixing of pigments.Traditional color theory was built around "pure" or ideal colors, characterized by different sensory experiences rather than attributes of the physical world. This has led to several inaccuracies in traditional color theory principles that are not always remedied in modern formulations. Another issue has been the tendency to describe color effects holistically or categorically, for example as a contrast between "yellow" and "blue" conceived as generic colors instead of the three color attributes generally considered by color science: hue, colorfulness and lightness. These confusions are partly historical and arose in scientific uncertainty about color perception that was not resolved until the late 19th century when artistic notions were already entrenched. They also arise from the attempt to describe the highly contextual and flexible behavior of color perception in terms of abstract color sensations that can be generated equivalently by any visual media.
Primary colors
Color theory asserts three pure primary colors that can be used to mix all possible colors. These are sometimes considered as red, yellow and blue or as red, green and blue. Ostensibly, any failure of specific paints or inks to match this ideal performance is due to the impurity or imperfection of the colorants. In contrast, modern color science does not recognize universal primary colors and only uses primary colors to define a given color space. Any three primary colors can mix only a limited range of colors, called a gamut, which is always smaller than the full range of colors humans can perceive. Primary colors also can't be made from other colors as they are inherently pure and distinct.Complementary colors
For the mixing of colored light, Isaac Newton's color wheel is often used to describe complementary colors, which are colors that cancel each other's hue to produce an achromatic light mixture. Newton offered as a conjecture that colors exactly opposite one another on the hue circle cancel out each other's hue; this concept was demonstrated more thoroughly in the 19th century. An example of complementary colors would be magenta and green.A key assumption in Newton's hue circle was that the "fiery" or maximum saturated hues are located on the outer circumference of the circle, while achromatic white is at the center. Then the saturation of the mixture of two spectral hues was predicted by the straight line between them; the mixture of three colors was predicted by the "center of gravity" or centroid of three triangle points, and so on.
According to traditional color theory based on subtractive primary colors and the RYB color model, yellow mixed with purple, orange mixed with blue, or red mixed with green produces an equivalent gray and are the painter's complementary colors.
One reason the artist's primary colors work at all is due to the imperfect pigments being used have sloped absorption curves and change color with concentration. A pigment that is pure red at high concentrations can behave more like magenta at low concentrations. This allows it to make purples that would otherwise be impossible. Likewise, a blue that is ultramarine at high concentrations appears cyan at low concentrations, allowing it to be used to mix green. Chromium red pigments can appear orange, and then yellow, as the concentration is reduced. It is even possible to mix very low concentrations of the blue mentioned and the chromium red to get a greenish color. This works much better with oil colors than it does with watercolors and dyes.
The old primaries depend on sloped absorption curves and pigment leakages to work, while newer scientifically derived ones depend solely on controlling the amount of absorption in certain parts of the spectrum.