Early search termination for fast motion estimation

This paper proposes a novel method for early termination of a motion search. It first introduces an estimator of the sum of absolute difference (SAD) between the current block and a search point. After analyzing the SAD estimator, it proposes the SAD condition to decide whether the current search point is around a minimum point or not. The counter condition is used to evaluate the current search point as an early search termination cue. After the current search point is considered as a minimum point, the search is stopped immediately. The proposed algorithm can easily be combined with most existing fast motion estimation algorithms to further reduce computational cost. While previous thresholding techniques have focused on the correlation of SAD values between a current block and its neighboring blocks, the proposed algorithm studies its own characteristics to predict the threshold. Hence, the proposed termination scheme can complement the previous early search termination techniques by merging the termination methods together, in order to further reduce computational cost. Experimental results demonstrate that the proposed algorithm successfully reduces the computational cost by combining the previous early search termination techniques.