RYB color model



RYB (an abbreviation of red-yellow-blue) is a historical set of colors used in subtractive color mixing, and is one commonly used set of primary colors. It is primarily used in art and design education, particularly painting.

It predates much of modern scientific color theory, which has demonstrated that magenta, yellow, and cyan is the optimal set of three colors to use when mixing pigment. Red can be produced by mixing magenta and yellow, blue can be produced by mixing cyan and magenta, and green can be produced by mixing yellow and cyan. In the RYB model, red takes the place of magenta, and blue takes the place of cyan.

However, reproducing the entire range of human color vision with three primaries either in an additive or subtractive fashion is generally not possible; see gamut for more information.

Color wheel
RYB (red-yellow-blue) make up the primary color triad in a standard artist's color wheel. The secondary colors VOG (violet-orange-green) also make up another triad. Triads are formed by 3 equidistant colors on a particular color wheel. Other common color wheels represent the light model (RGB) and the print model (CMYK).

History


In his experiments with light, Isaac Newton recognized that colors could be created by mixing color primaries. In his Opticks, Newton published a color wheel to show the geometric relationship between these primaries. This chart was later confused and understood to apply to pigments as well, though Newton was also unaware of the differences between additive and subtractive color mixing.

The RYB model was used for printing, by Jacob Christoph Le Blon, as early as 1725.

In the 18th century, the RYB primary colors became the foundation of theories of color vision, as the fundamental sensory qualities that are blended in the perception of all physical colors and equally 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 Colors (1810) by the German poet and government minister Johann Wolfgang von Goethe, and The Law of Simultaneous Color Contrast (1839) by the French industrial chemist Michel-Eugène Chevreul.

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 (RGB) uni modeled through the additive, rather than subtractive, mixture of three monochromatic lights.

Painters have long used more than three RYB primary colors in their palettes – and at one point considered red, yellow, blue, and green to be the four primaries. Red, yellow, blue, and green are still widely considered the four psychological primary colors, though red, yellow, and blue are sometimes listed as the three psychological primaries, with black and white occasionally added as a fourth and fifth.

The cyan, magenta, and yellow primary colors associated with CMYK printing are sometimes known as "process blue", "process red", and "process yellow".