Pel Recursive Technique
The pel recursive technique is one of the three major approaches to two-dimensional (2-D) displacement estimation in image planes for the signal processing community. Conceptually speaking, it is one type of region matching technique. This chapter provides a general description of the recursive technique. It covers some fundamental techniques in optimization. The chapter describes the Netravali and Robbins algorithm, the pioneering work in this category. It introduces several other typical pel recursive algorithms. The chapter gives a performance comparison between these algorithms. In 1979 Netravali and Robbins published the first pel recursive algorithm to estimate displacement vectors for motion compensated interframe image coding. When handling the displacement estimation as a nonlinear programming problem in the pel recursive technique, the first algorithm developed by Netravali and Robbins is essentially the steepest descent method.