Motion-compensated prediction is a key technique for achieving high compression performance for a video sequence. Exhaustive search produces the best predictor block but requires intensive computation and expensive hardware. This paper presents a 4:1 checker-board algorithm that reduces the computational complexity of exhaustive search by a factor of 8 while maintaining similar video quality. The algorithm subsamples block pixels by four to one, wand subsamples search locations by two to one. The resulting architecture is simple and scalable, and is suitable for real-time encoding.
Belle W. Y. Wei,
"4:1 checkerboard algorithm for motion estimation", Proc. SPIE 2847, Applications of Digital Image Processing XIX, (14 November 1996); doi: 10.1117/12.258249; https://doi.org/10.1117/12.258249