Steerable Wedge Filters for Local Orientation Analysis

Steerable filters have been used to analyze local orientation patterns in imagery. Such filters are typically based on directional derivatives, whose symmetry produces orientation responses that are periodic with period ß, independent of image structure. We present a more general set of steerable filters that alleviate this problem. 1 Introduction Oriented linear filters are used in many vision and image processing tasks, such as edge detection, segmentation, texture analysis, and motion analysis. Their basic behavior with regard to representation of orientation may be examined by computing an "orientation map": the squared filter response as a function of filter orientation (e.g., [4, 3, 8, 2]). Such filters are almost always either symmetric or anti-symmetric. The symmetry (or anti-symmetry) of the filters imposes a periodicity (of period ß) on the orientation map, regardless of the underlying image structure. For example, an orientation map computed at the end of a line segment will..