Estimation of multiple light sources from specular highlights

This paper proposes a method for estimating the illuminant spectral power distributions and their positional relationship of multiple light sources under a complex illumination environment. A multiband camera system is used for capturing spectral images of dielectric objects in a scene. Specular highlights are used as a clue for estimating the light source information, which are detected on curved object surfaces with the different object colors. The illuminant spectra of light sources are estimated from the camera data for each highlight areas. Then, the illuminant spectral estimates are obtained for a different set of light sources. Next, positional relationship among the light sources is predicted by classifying the detected highlights and the estimated spectra using the probabilistic relaxation labeling. The feasibility of the proposed method is examined in experiments on real scenes.