Abstract
Images of glossy objects contain specular highlights. Human perception of gloss is correlated with such properties of the highlight field as luminance, contrast, highlight sharpness and coverage. However, these image properties are not only determined by object shape and surface reflectance, but also by characteristics of the illumination field. We explore the perception of gloss under complex, natural light fields and ask whether observers use the statistics of the light field to improve gloss constancy under changing illumination. Observers viewed pairs of smooth, random ‘potato’ objects and judged which was glossier in a 2-interval, forced-choice paradigm. Objects of varying specularity were rendered and displayed in complex, high dynamic range, natural light fields (spherical images of a scene from a single viewpoint), taken from the Southampton-York Natural Scenes (SYNS) dataset. Within any single trial, both objects were rendered as if placed in the same light field. One object was displayed with, as background, the visible portion of the light field with which it was rendered (‘congruent’); the other was displayed against another, incongruent light field. We found modest but systematic effects of the incongruent light field. For example, when the incongruent light field in the background was a similar scene to the congruent one, but with artificially high contrast, the objects displayed against it were perceived as less glossy than those shown against the congruent light field. Observers also showed partial gloss constancy---using the background to interpret perceived gloss of the object---when objects were displayed against a novel, incongruent light field, or one that had been manipulated to simulate a low-contrast, foggy environment. Our findings suggest that observers are sensitive to the context in which objects are presented when making judgments of surface gloss.
Meeting abstract presented at VSS 2015