Abstract

The interest in studying symmetry from an interdisciplinary perspective is due to the fact that a great variety of symmetrical structures exists not only in nature but also in art, music and cultural symbols. Gestalt psychology has recognized its salient role in perceptual organization, describing how observers tend to see objects as symmetrical structures displayed around a center. Actually human judging symmetry is quite different from geometric definition, since it critically depends on gravity; in addition, in accordance with Gestalt principles, the human eye is predisposed toward emphasizing natural symmetries, which are only imprecise approximations of mathematical ones. Considering the differences between natural and mathematical symmetries, in this paper we give a short review of the most important algorithms that have been proposed in artificial vision to detect various kinds of symmetry.