The resonator theory of colour vision

The resonator theory claims that light scattering by the melanin granules of the retinal pigment epithelium causes light to be reflected back through the outer segment of the cones, in a direction opposite that of the incident light. These two opposite directed wave motions may produce standing waves inside the cone outer segment, which then acts as a resonating cavity for light waves. The wavelength specificity of the single cone is determined by the length and the diameter of the cone outer segment. The variation of the length and the diameter of the cone outer segments throughout the retina is then the basis of colour discrimination.