The smoothest reflectance function [ J. Opt. Soc. Am. A 7, 1891 ( 1990)] is considered an estimate of the actual reflectance function with the same tristimulus values under the given illuminant. The estimate differs from the actual function by a so-called metameric black. The metameric black depends on a number of parameters that are inaccessible to the visual system and describes the uncertainty with which the visual system has to cope when illuminant-independent properties of reflectance are being predicted. Illuminant-independent properties of reflectance are determined that can be predicted with little uncertainty and that therefore can be calculated in good approximation from the estimate of the actual reflectance function. The result is an estimate of the property that is, by construction, almost independent of the illuminant and thus in principle is able to explain color constancy. Such a property, a weighted mean of reflectance yielding an achromatic variable, is constructed; the predictions are verified numerically; and the result is compared with experiment.
© 1994 Optical Society of America
Original Manuscript: May 20, 1992
Revised Manuscript: August 31, 1993
Manuscript Accepted: September 1, 1993
Published: March 1, 1994
C. van Trigt, "Metameric blacks and estimating reflectance," J. Opt. Soc. Am. A 11, 1003-1024 (1994)