Reused sad for partial search area in efficient three‐step search algorithm

Abstract

In real‐time applications, three‐step search (TSS) is always preferred because it has a regular search pattern. However, it may lose its performance in coding video sequences with small motion. To overcome this drawback, some fast search algorithms are proposed, for example, new three‐step search (NTSS) and efficient three step search (ETSS). In this paper, a more effective fast search algorithm called region‐split three‐step search (RSTSS) is proposed. In addition to the feature of a regular search pattern, the RSTSS splits the search region into four sub‐regions and enters only one of the sub‐regions to search for the best motion vector. The main idea used in the RSTSS is to reuse the sum of absolute difference (SAD) values of the 9 points on a 9 ×9 grid. Experimental results show that the RSTSS performs better than the ETSS in terms of the number of checking points. It can reduce the number of checking points nearly 19% on average and sacrifices only a little mean squared error. Most of all, the RSTSS retains a regular searching pattern that is suitable for hardware implementation.