Pattern orientation and texture symmetry

Human texture perception relies on a few basic high-level features including directionality and symmetry. Today, research on oriented patterns finds its applications in various areas of applied machine vision. In this study, we present and investigate a new method for assessing pattern anisotropy via texture symmetry. Pattern orientation is viewed as the direction of persistent statistical texture symmetry. The proposed method uses the spatial dependence of an extended spatial gray-level difference feature to yield an interaction symmetry map which reflects the symmetry of both short- and long-range pixel interactions. Pattern orientation can then be assessed via the directions of global symmetry — the characteristic axes of the pattern. Experimental results are shown which support our claim that texture symmetry is deeply related to the perceived orientation. The results are compared to the orientations obtained in a recent study that uses the traditional filtering framework. The properties of the two approaches are compared and discussed.