Multiple initial point prediction based search pattern selection for fast motion estimation
A novel, computationally efficient and robust scheme for multiple initial point prediction has been proposed in this paper. A combination of spatial and temporal predictors has been used for initial motion vector prediction, determination of magnitude and direction of motion and search pattern selection. Initially three predictors from the spatio-temporal neighboring blocks are selected. If all these predictors point to the same quadrant then a simple search pattern based on the direction and magnitude of the predicted motion vector is selected. However if the predictors belong to different quadrants then we start the search from multiple initial points to get a clear idea of the location of minimum point. We have also defined local minimum elimination criteria to avoid being trapped in local minimum. In this case multiple rood search patterns are selected. The predictive search center is closer to the global minimum and thus decreases the effect of monotonic error surface assumption and its impact on the motion field. Its additional advantage is that it moves the search closer to the global minimum hence increases the computation speed. Further computational speed up has been obtained by considering the zero-motion threshold for no motion blocks. The image quality measured in terms of PSNR also shows good results.
motion estimation spatial temporal motion vectors block matching correlation video coding