Evolution of human colour vision as 'visual purple' receptor proteins, are encoded by Rh1, OPN2 and RHO genes. They are characterized by extreme sensitivity to light and enable monochromatic human vision in low light or dim conditions. They are broken down into retinal and opsin when exposed to these conditions. Humans have 3 types of photopsin proteins found in the cone cells. Long Wavelength Sensitive Opsin (Red cone opsin) – Encoded by the OPN1LW gene with a λmax of 560 that is found in the yellow-green electromagnetic spectrum despite its name. Its sensitivity to the colour red is still known to be higher than the
George Palmer (colour theorist) Leipzig four short works on various inventions, one being a fire-extinguishing powder. A demonstration in a pharmacy of the use of the powder was described in a Niedersachsen newspaper. In 1811 Palmer moved to Copenhagen into retirement and died there destitute in 1826. Palmer made a lasting contribution to the development of colour science by being the first to speculate that there are three different mechanisms in the human eye that account for colour vision: "The superficies of the retina is compounded of particles of three different kinds, analogous to the three rays of light; and each of these particles