LINEAR BASES FOR SPECTRAL REFLECTANCE FUNCTIONS OF ACRYLIC PAINTS

A linear model for representing reflectances has been developed from a group of 5574 samples of acrylic paint on paper Using acrylic paints makes easy the generation of a large variety of samples by mixing, due to the high miscibility among these kinds of pigments: this point was the key to achieve a great spatial homogeneity in our samples. Beside s, these kinds of paints keep their chromatic properties stable over t ime. The first 7 vectors of the so-called overall linear basis were su fficient for a more than adequate mathematical representation of the s pectral-reflectance curves. A study by hue groups of the mathematical properties of these curves indicates that the nse of a hue basis of re presentation implies, on the average, a reduction in 1 or 2 of the num ber of vectors needed in order to achieve results analogous to those o f the over-all basis. (C) 1998 John Wiley & Sons, Inc.