Inferring illumination direction estimated from disparate sources in paintings:: An investigation into Jan!Vermeer's Girl with a pearl earring

The problem in computer vision of inferring the illumination direction is well studied for digital photographs of natural scenes and recently has become important in the study of realist art as well. We extend previous work on this topic in several ways, testing our methods on Jan Vermeer's Girl with a pearl earring (c. 1665-1666). We use both model-independent methods (cast-shadow analysis, occluding-contour analysis) and model-based methods (physical models of the pearl, of the girl's eyes, of her face). Some of these methods provide an estimate of the illuminant position in the three dimensions of the picture space, others in just the two dimensions of the picture plane. Our key contributions are a Bayesian evidence integration scheme for such disparate sources of information and an empirical demonstration of the agreement, or at least consistency, among such estimates in a realist painting. Our methods may be useful to humanist art scholars addressing a number of technical problems in the history of art.