Grey on televisions, computer displays and telephones is usually created using the RGB color model. Red, green, and blue light combined at full intensity on the black screen makes white; by lowering the intensity, it is possible to create different shades of grey. In printing, grey is usually obtained with the CMYK color model, using cyan, magenta, yellow and black. Grey is produced either by using black and white, or by combining equal amounts of cyan, magenta and yellow. Most greys have a cool or warm cast to them, as the human eye can detect even a minute amount of color
Conservation and restoration of photographs Additive Color Model Applied physician James Clerk Maxwell made the first color photo by mixing red, green, and blue light. 1871: Gelatin dry plate Richard L. Maddox discovered that gelatin could be a carrier for silver salts. By 1879, the gelatin dry plate had replaced the collodion wet plate. It was a revolutionary innovation in photography since it needed less light exposure, was usable when dry, meaning photographers no longer needed to pack and carry dangerous liquids, and could be standardized because it could be factory produced. 1873: Platinum Printing (Platinotype) William Willis patented platinum printing in Britain. The process