Due to the temporal and spatial correlation of the image sequence, the moti
on vector of a block is highly related to the motion vectors of its adjacen
t blocks in the same image frame. If we can obtain useful and enough inform
ation from the adjacent motion vectors, the total number of search points u
sed to find the motion vector of the block may be reduced significantly, Us
ing that idea, an efficient gray prediction search (GPS) algorithm for bloc
k motion estimation is proposed in this paper. Based on the gray system the
ory, the GPS can determine the motion vectors of image blocks quickly and c
orrectly. The experimental results show that the proposed algorithm perform
s better than other search algorithms, such as 3SS, CS, PHODS, 4SS, BBGDS,
SES, and PSA, in terms of six different measures: 1) average mean square er
ror per pixel; 2) average peak signal-to-noise ratio; 3) average prediction
errors per pixel; 4) average entropy of prediction errors; 5) average perc
entage of unpredictable pels per frame; and 6) average search points per bl
ock.