The increasing research and debate during the last decade on the use of color as an information code indicates that color displays are here to stay—because they are preferred to monochrome displays and because they are generally more effective, provided the color coding is done properly.
Depending on the function of the colors, the requirements for legibility, color differences, color contrasts, and color appearance may be widely different.
To meet design requirements for video display units (VDUs), perceptually based color spaces are needed. During the last decade color appearance systems have come into use for color selection in color VDUs. These systems are gaining prominence over colors defined in numerical RGB values, which are not related to the perceptually relevant dimensions of hue, chroma (chromaticness, saturation), lightness, and blackness. We have developed a 'Palette' based on the Natural Color System (NCS) and on the CIE 1976 (L* u* v* ) system (CIELUV). With the 'Palette', colors can be selected interactively as well as automatically, according to a) NCS notations and/or CIELUV values, b) every day language or, c) the functional significance of the color in the image. A palette is presented in a frame around the image. The user is then free to try the different colors one at a time at his/her convenience.