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Adaptive irregular pattern search with matching prejudgment for fast block-matching motion estimation

In this paper, a simple and effective fast block matching algorithm (BMA) is proposed, called adaptive irregular pattern search with matching prejudgment (AIPS-MP). In the AIPS-MP, a dynamic search pattern, adaptive irregular pattern (AIP), is constructed for each block based on its spatial and temporal neighboring motion vectors (MVs). The AIP is used to quickly identify the best center point for the follow-up refined search to effectively reduce unnecessary intermediate searches and avoid the search trapping at local-minimum matching error position. The construction of the AIP jointly takes the tradeoff of rate and distortion into consideration and favors the differential coding of MVs. The matching prejudgment (MP) is imbedded in the AIPS and exploits an adaptive threshold determined for each block based on the prediction error of the temporal neighboring block. The simulation results show that the proposed AIPS-MP consistently achieves very close, and sometimes even higher, peak signal-to-noise ratio (PSNR) than the full search, while achieving 167.6-871.5 times of speed-up or computational gain, measured in terms of the average number of search points per MV generation. It also greatly outperforms two well-referenced fast BMAs, the diamond search and the motion vector field adaptive search technique (MVFAST), adopted in the MPEG-4 Verification Model and the Optimization Model, respectively, on the average PSNR and the search speed.