A dynamic search window adjustment for block-matching algorithm (BMA) based on the block similarity is presented to reduce the computational complexity of full search BMA. The adjustment of the size of the search window is performed in three steps: (1) set a new search origin based on the block similarity and the displaced block difference (DBD), (2) adjust the size of search window in inverse proportion to block similarity, and (3) update the thresholds for accommodation to a given image sequence. The technique can be easily applied to full search BMA and several fast search algorithms to get more efficiency and to reduce a possibility of falling into a local minimum. Experimental results show that the proposed technique has a good MSE performance and reduces the number of search points substantially. (C) 1998 SPIE and IS&T. [S1017-9909(98)02303-4].