Young–Helmholtz theory

[1] Hermann von Helmholtz developed the theory further in 1850:[2] that the three types of cone photoreceptors could be classified as short-preferring (violet), middle-preferring (green), and long-preferring (red), according to their response to the wavelengths of light striking the retina.

For instance, yellow light uses different proportions of red and green, but little blue, so any hue depends on a mix of all three cones, for example, a strong red-sensitive, medium green-sensitive, and low blue-sensitive.

The system is not perfect, as it does not distinguish yellow from a red-green mixture, but can powerfully detect subtle environmental changes.

In 1857, James Clerk Maxwell used the recently developed linear algebra to offer a mathematical proof of the Young–Helmholtz theory.

[4] In 1983 it was validated in human retinas in an experiment by Herbert Dartnall, James Bowmaker, and John Mollon, who obtained microspectrophotopic readings of single eye cone cells.