observer. The seven-field colorimeter was also used for a novel color-difference matching experiment in which three fields were displayed and the observer had to adjust the third field so that its brightness matched the brightness of preselected colors with equal luminance in two fields and its chromaticity resulted in identical perceived differences between the colors in the triangular arrangement. Heterochromatic brightness matching: Wyszecki and co-workers also added important experimental data to the luminance of equally bright stimuli. Many chromatic stimuli, when compared to achromatic ones of the same psychophysical brightness or lightness appear to be lighter or brighter, to be "glowing," an effect known as the Helmholtz–Kohlrausch effect. Publications Wyszecki authored or co-authored 86 scientific papers and 3 books. The first book, Farbsysteme was published in Germany in 1960, describing color order systems. He co-authored together with Deane Judd the second and third editions of the latter's Color in Business, Science and Industry, the third edition after the passing of Judd. He was the lead author, together with Stiles, of the monumental Color Science: Concepts and Methods, Quantitative Data and Formulae, with editions in 1967 and 1982. The second edition remains in print today as a highly important source of information in the field of color science. References 1925 births 1985 deaths German emigrants to Canada People from Tilsit People from East Prussia 20th-century Canadian physicists 20th-century German physicists Color scientists