Ellen C. Carter

Color and conspicuousness

The principle that things are easier to find if they contrast with their environment is expressed quantitatively. Two indices of conspicuousness, relative fixation rate and search time, are shown to be related to the color difference between the target and background objects. The color difference equations used are CIELAB, CIELUV, and the Judd modification of the index of fading. None of the equations is superior to the others. Furthermore, neither Judds modification nor Semmelroths adjustment accounts for effects of surround lightness. It is suggested that color difference be used as a tool for design and evaluation of visual displays, for construction of color codes to optimize search time, and as a generalization of chromatic contrast in psychophysical research.

High-contrast sets of colors

A method is presented for choosing high-contrast sets of colors for additive color mixers (e.g., CRT). The method is based on data about target-location performance of human observers and adapts the color sets to the gamut of the color processor in use. The method produces any specified number of colors spread as far from each other as possible in color space to maximize contrast. Applications of high-contrast sets of colors are indicated, illustrative results are presented and discussed, and variations of the method are suggested.

Modeling Of Display Color Parameters And Algorithmic Color Selection

A complex and difficult problem for the design of color display systems is the selection of a repertoire of display colors. Color selection is the process in which display visual parameters, operational ambient lighting characteristics, and human visual/perceptual functions are integrated for the purposes of specifying an optimized set of display colors. The object of color selection is not necessarily one of establishing an aesthetic repertoire of display colors, but rather the goal is to select a minimum set of colors that maximize the visual utility and information transfer capabilities of the display. The present paper describes a unique, algorithmic approach to color selection which is based upon psychophysical models of color processing. The selection algorithm, currently implemented on a personal computer, seeks to develop color sets of specified numbers in which the minimum color difference between any pair of colors in the set is maximized. In addition, the computer program combines the selection algorithm with internally derived correction factors for color image field size, ambient lighting characteristics, and anomalous red-green color vision deficiencies of display operators. The program and color selection algorithm together provide an extremely powerful tool for color display system design.