We suggest dichromatic reflection models adequate for describing surface-spectral reflectances of a variety of materials. First we describe the standard dichromatic reflection model for inhomogeneous dielectric materials. Next the generalized models are shown for describing the spectral reflectances of the materials for which the standard model is inadequate. The reflection characteristics are analyzed on a chromaticity diagram. We demonstrate practical use of the reflectance models in computer graphics and color constancy.
Shoji Tominaga, "Using Reflectance Models for Surface Estimation" in Proc. IS&T 3rd Color and Imaging Conf., 1995, pp 29 - 33, https://doi.org/10.2352/CIC.1995.3.1.art00008