Abstract

The standard reflectance model for inhomogeneous materials suggests that to a good approximation the reflectance function can be described as the weighted sum of two functions^1,2. One function represents the interface (specular) reflection, and the second function represents the subsurface (diffuse) reflection. Let S_I(λ) and S_S(λ) be the surface spectral reflectances for the two components of interface and subsurface reflections, and let E(λ) be the spectral power distribution of the incident light. Then reflected light is where c_I(θ) and c_S(θ) are the geometric scale factors. The parameters θ vary with the viewing geometry. In a previous paper² we have evaluated this model and shown how to use light reflected from pairs of surfaces to estimate the spectral power distribution of the illuminant.

© 1989 Optical Society of America