Estimation of Two Illuminant Spectral Power Distributions from Highlights of Overlapping Illuminants

A method is proposed for estimating two illuminant spectral power distributions from the highlights of overlapping illuminants on an object. It was assumed in most previous studies that specular highlights on object surfaces are caused by a single light source, or by separate multiple light sources. In this paper, we assume that two highlights from different light sources are overlapped on object surfaces, and estimate the spectral power distributions of both. A multiband camera system is used for capturing spectral images of dielectric objects in a scene. First, we detect specular highlight areas from the spectral image. Then, the illuminant spectra of two light sources are simultaneously estimated based on cluster classification of particular pixel distribution in the highlight area. The feasibility of the proposed method is examined in experiments on real-world scenes.