Black, white, and grays: are they colors, absence of color or the sum of all colors?

Abstract

Sometimes it is said that white is not a color but “the sum of all colors.” Surely this confusion comes from considering colors only those that appear in the spectrum. If these were the only colors, then magenta would neither be a color, nor do brown and other colors that do not have a specific wavelength, but are produced by a mixture of different wavelengths. Contradictorily, white often appears as “the absence of color.” When pigments are used on canvas or paper, white is the surface that remains unpigmented, unpainted, “uncoloured.” The same confusion often occurs with regard to black. Black is said to be “the sum of all colors” when a blackish stain is obtained from the mixture of various pigments. And black is said to be the “absence of color” when all light radiation is removed. The aim of this article is to argue that black and white are also colors, and so are grays. Because color is a visual sensation (product of the interaction of luminous radiation with pigmented objects and observers). “Pigment” and “color” are not synonymous; “light radiation” and “color” are not synonymous either. And just as we have red, green, blue, or yellow visual sensations, we also have visual sensations of white, black, or gray. This argument is supported by a survey where lay people and experts are asked about this issue, and by a bibliographical research that looks into texts and color order systems developed by theorists since the ancient times to nowadays.