Fast Screening Algorithm for Template Matching

Abstract

This paper presents a generic pre-processor for expediting conventional template matching techniques. Instead of locating the best matched patch in the reference image to a query template via exhaustive search, the proposed algorithm rules out regions with no possible matches with minimum computational efforts. While working on simple patch features, such as mean, variance and gradient, the fast pre-screening is highly discriminative. Its computational efficiency is gained by using a novel octagonal-star-shaped template and the inclusion-exclusion principle to extract and compare patch features. Moreover, it can handle arbitrary rotation and scaling of reference images effectively, and also be robust to uniform illumination changes. GPU-aided implementation shows great efficiency of parallel computing in the algorithm design, and extensive experiments demonstrate that the proposed algorithm greatly reduces the search space while never missing the best match.