Primary colors are sets of colors that can be combined to make a useful range (gamut) of colors. For human applications, three are often used; for additive combination of colors, as in overlapping projected lights or in CRT displays, the primary colors normally used are red, green, and blue. For subtractive combination of colors, as in mixing of pigments or dyes, such as in printing, the primaries normally used are magenta, cyan, and yellow.[1]
Any choice of primary colors is essentially arbitrary; for example, an early color photographic process, autochrome, typically used orange, green, and violet primaries.[2]
Psychovisual studies and the opponent process color model lead to the notion of four "pure" or "unique" colors:[23] red, yellow, green, and blue, with red and green defining one color-opponent axis, and yellow and blue a second color-opponent axis.
basic colors cannot be created by mixing other colors.In the 1969 study Basic Color Terms: Their Universality and Evolution, Brent Berlin and Paul Kay describe a pattern in naming "basic" colors (like "red" but not "red-orange" or "dark red" or "blood red", which are "shades" of red). All languages that have two "basic" color names distinguish dark/cool colors from bright/warm colors. The next colors to be distinguished are usually red and then yellow or green. All languages with six "basic" colors include black, white, red, green, blue and yellow. The pattern holds up to a set of twelve: black, grey, white, pink, red, orange, yellow, green, blue, purple, brown, and azure (distinct from blue in Russian and Italian but not English).