LINEAR BASES FOR REPRESENTATION OF NATURAL AND ARTIFICIAL ILLUMINANTS

By the principal-value decomposition process, we have obtained two lin ear bases for representing the spectral power distributions of illumin ants, applicable for algorithms of color synthesis and analysis in art ificial vision: one from experimental measurements of daylight and ano ther combining both natural and artificial illuminants. The first basi s adequately represents daylight with dimension 3, in accordance with the previous results of Judd et al. [J. Opt. Soc. Am. 54, 1031 (1964)] ; however, it does not adequately represent artificial illuminants, ev en with a higher dimension. In the case of the second basis, many good results are obtained in the reconstruction of the spectral power dist ribution both of daylight and of artificial illuminants, including som e fluorescent lights, with dimension 7 or even less. In consequence, w e show the possibility of obtaining linear bases of a low dimension, e ven when the set of illuminants that we try to represent presents a ce rtain variability in shape. (C) 1997 Optical Society of America.