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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 . While the science may be quite difficult to understand most users of the system will simply be choosing or matching colors with printed reference cards. The underlying physiological mechanisms involved in color opponency include the Bipolar and Ganglion Cell s in the Retina , which process the signal originated by the Retinal Cone s 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 Set s and Computer Display s. The NCS model, for its part, claims to describe the organization of the color sensations as perceived at the upper, brain level, and to be much better fitted than RGB to deal with how humans experience and describe their color sensations (hence the "natural" part of its name); but it would be useless, for example, for describing the behaviour of mixing lights and pigments. The NCS is based on the hypothesis that there are six elementary Color percepts of human vision as described by color opponency— White , Black , Red , Yellow , Green , and Blue — and that none of these perceptually can be defined in terms of the others (for example, it is claimed that one could not describe color red as looking "like a yellow and magenta mixture", even though you will in fact get a red pigment by mixing yellow and magenta pigments). This hypothesis is also seen as an explanation for the fact that these six elementary colors are those most frequently chosen to paint educational toys, or for designs that try to appeal from their simplicity (such as the Olympic Flag and the Microsoft Windows logo). All the other perceptual colors are claimed to be composite perceptions that can be defined in terms of those six (for example, turquoise looks like "blue-green", orange like "a color that is both reddish and yellowish", and brown looks like "a very dark orange", that is, like a mixture of red, yellow and black). As a system that is partly analog to the subtractive system of color mixing, the NCS notation obviously predicts the appearance of a color more readily than an additive system such as RGB where the notation is unintuitive. Yellow does not look like a reddish-greenish color at all, although it can be caused by mixing red and green light from a monitor, as directly indicated by the RGB system. In this case the lack of intuitiveness parallels the physical process of paint mixing: adding red paint to green does not render a yellow hue. However the NCS is also claimed to be intuitively superior to a derived subtractive CMY system, even when the latter system is superior in predicting the results of physical mixing. For example, green is claimed not to look like "a cyan-yellowish color", even though green paint can be obtained, as predicted by the RGB-CMY system, by mixing cyan and yellow paint; but saturated magenta is claimed to look like a mixture of blue and red, even though it cannot be obtained by mixing red and blue paint. It is also claimed that under normal viewing circumstances, there would be not a single hue that one could describe as a mixture of opponent hues; that is, not only would "yellowblue" not exist, but there would also not be a hue looking "redgreen" even though mixing red end green paint renders a olive green as predicted by the RGB-CMY system (see note in the Color Opponents article; the "blue" in "yellowblue" would be the complementary color of yellow, or "violet"). Colors in the NCS are defined by three values, specifying the amount of blackness (i.e. darkness), Chromaticity (i.e. Saturation ), and a Percentage value between two of the colours red, yellow, green or blue (i.e. Hue ). The blackness and the chromaticity together add up to less than or equal to 100%--their remainder from 100%, if any, gives the amount of whiteness. The complete NCS color notations can also be tagged with a letter giving the version of the NCS color standard that was used to specify the color. Two examples of NCS color notation—the yellow and blue shades of the Swedish Flag :
The NCS is represented in 19 countries and is the reference norm for color designation in Sweden (since 1979 ), Norway (since 1984 ) and Spain (since 1994 ). It is also one of the standards used by the International Colour Authority , a leading commercial publisher of color trend forecasts for the interior design and textile markets. EXTERNAL LINKS
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