Estimating source spectra and spectral albedos from RGB data for rerendering

Abstract

I consider the problem of estimating material properties (the spectral albedo) on the basis of -object colors- (at worst only RGB data say). I show how to obtain a priori likely estimates for the white point, the spectral composition of the source, and the spectral albedos of the objects in a scene. I also show how to construct the general solutions. These general solutions are so broad as to render them practically useless. There are good reasons to disregard the larger part of the solution space, because very general considerations suggest that the specific solutions constructed with the methods discussed here are very likely to yield sensible and useful results in practice. From a principled perspective it is desirable to be able to construct the full solution space though. Since the results are in the scene, rather than the image domain, they are suitable for rerendering purposes.