A new technique for local symmetry estimation

Abstract

This paper introduces a new approach to symmetry estimation directly from image grey values. The method was inspired by the local phase based method, proposed by Kovesi. This method is examined in the light of a strict definition of local symmetry, and found to be wanting in two respects: that it is invariant to some apparently non-trivial symmetries and that its scale is ill defined. To avoid these difficulties we propose a non-linear analog of the local phase. This leads to a family of local symmetry measures, able to provide a rich, local characterisation of shape, invariant to rotations and affine intensity transformations, and robust to affine coordinate transformations. © Springer-Verlag Berlin Heidelberg 2005.