When the brightest is not the best: illuminant estimation from the geometry of specular highlights

Color constancy allows us to perceive stable object colors under different lighting conditions by reducing the impact of lighting. Information about illuminant color could be derived from a white surface or a specular highlight. The 'brightest is white' heuristic has been frequently incorporated in illumination estimation models, to identify illuminant color. Here, we tested an alternative hypothesis: we use structured changes in the proximal image to identify highlight regions, even when they are not the brightest elements in the scene. In computer-rendered scenes, we varied the reliability of 'brightest element' and 'highlight geometry' cues, testing their effect on a color constancy task.