Constrained growing based variable size block motion estimation

Most variable size block motion estimation (VSBM) algorithms suffer from intensive computational load resulting from a bottom-up style of motion vector field building. Focusing on this problem, an optimized quad-tree growing VSBM algorithm with top-down style is proposed and a constrained growing VSBM algorithm is presented in detail. An efficient constrained growing algorithm is implemented by a combination of a fast sorting method, an improved quad-tree code and fast motion vector searching methods. The simulation results show that a dense sub optimum rate-distortion curve can be obtained with a more competitive lower complexity.