Efficient motion vector refinement architecture for sub-pixel motion estimation systems

This paper proposes a new, scalable and efficient VLSI architecture for real-time sub-pixel motion estimation. The proposed structure is optimized for search strategies using small search ranges, such as hierarchical or sub-pel refinement algorithms. Based on the proposed architecture, a highly modular and configurable motion estimation co-processor capable of estimating optimal motion vectors with any given accuracy and using any known interpolation algorithm is presented. The performance of this processing structure was evaluated by embedding it in a two-level motion estimation system with minimum memory bandwidth requirements, that estimates half-pixel accurate motion vectors using a two-step search procedure. Experimental results for implementations on ASIC and FPGA devices show that by using the proposed architecture it is possible to estimate motion vectors up to the 4CIF image format, in real-time with any given sub-pixel accuracy.