Speeding-up NCC-based template matching using parallel multimedia instructions

This paper describes the mapping of a recently introduced template matching algorithm based on the Normalized Cross Correlation (NCC) on a general purpose processor endowed with SIMD (Single Instruction Multiple Data) multimedia instructions. The algorithm relies on the Bounded Partial Correlation (BPC) technique, which consists in deploying a sufficient condition to detect unsatisfactory matching candidates at a reduced computational cost. First, we briefly describe the BPC technique and highlight the related expensive computations. Then, based on the analysis of the major SIMD multimedia instruction set extensions available nowadays, we define a processor-independent multimedia instruction set and show how to carry out the most expensive BPC calculations using these pseudo-instructions. Finally, we provide experimental results obtained mapping the proposed algorithm on a mainstream multimedia SIMD instruction set (i.e. MMX). We compare these results with those obtained with the brute force NCC algorithm. The results show that the BPC technique is suited for a parallel SIMD-style mapping and that its effectiveness can be significantly improved using the multimedia instructions available nowadays in most general purpose CPUs.