High Quality Content by WIKIPEDIA articles! The Natural Color System (NCS) is a proprietary perceptual color model published by the Scandinavian Colour Institute (Skandinaviska Färginstitutet AB) of Stockholm, Sweden. It is based on the color opponency description of color vision, first proposed by German physiologist Ewald Hering. The system is usually used for matching colors (using printed reference cards), rather than mixing colors. The underlying physiological mechanisms involved in color opponency include the bipolar and ganglion cells in the retina, which process the signal originated by the retinal cones before it is sent to the brain. A model like RGB describes what happens at the lower, retinal cone level, and thus is very well fitted for the task of "fooling the eye" as done by TV sets and computer displays.