Young-Helmholtz Theory

The original theory of trichromatic color vision, which describes a model that has since been proven to accurately describe the human color vision.

The theory was first proposed by Thomas Young in 1802, who postulated the existence of three types of photoreceptors (Cones) in the eye, with different but overlapping response to different wavelengths of visible light. Hermann von Helmholtz further refined the theory in 1850, in that the three types of cone photoreceptors could be classified as Short, Middle and Long, according to their Absorption Spectra. In 1857, James Maxwell amended the theory with a mathematical model. The theory would not be biologically proven until over a century later.

The theoretical Absorption Spectra of the three Photoreceptors postulated by the Young-Helmholtz theory. From the Handbuch der physiologischen Optik (Helmholtz 1860).