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In this thesis, we propose two new fast search algorithms in block motion estimation (BME) : the clustering search algorithm (CSA) and the two-way search algorithm (2WS).Besides CSA and 2WS, we also propose a new block matching method, named the dynamic-shaped block matching (DSBM), to achieve the better image quality.Basically, CSA is a feature-base search algorithm. It improves the search speed of BME by less calculated pixels within each block. CSA selects the most representative pixels of each block with the clustering technique, and refines the final motion vector by the center-biased concept.2WS is a position-base search algorithm. It improves the search speed of BME by reducing the checked blocks of search window in previous frame. 2WS does not only simply chooses two positions in each step but also finds the motion direction between every two steps. As for DSBM, it is a new block matching method whose blocks in each frame of a video do not need to be square. Moreover, all kinds of combinations of small blocks are taken into consideration in DSBM.DSBM therefore provides a better structure to get higher image quality in BME.
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