Irregular pattern matching using projections

Recently, a novel approach to pattern matching was introduced, which reduces time complexity by two orders of magnitude over traditional approaches. It uses an efficient projection scheme which bounds the distance between a pattern and an image window using very few operations on average. The projection framework combined with a rejection scheme allows rapid rejection of image windows that are distant from the pattern. One of the limitations of this approach is the restriction to square dyadic patterns. In this paper we introduce a scheme, based on this approach which allows fast search for patterns of any size and shape. The suggested method takes advantage of the inherent recursive tree-structure introduced in the original scheme.