| 摘要 |
The present invention discloses an improved method and apparatus for prediction coding with motion estimation, in which the frame-to-frame changes resulting from motion in an image depicted in a video frame are detected and coded for transmission to a video receiver. The motion estimation technique of the present invention uses a hierarchical approach in which a motion vector updating routine is performed with respect to multiple levels of smaller and smaller regions of a frame. The motion vector updating routine updates the motion vector of a smaller region by assigning to it a best motion vector selected from among an initial motion vector assigned to the smaller region, motion vectors of neighboring regions, and a matched motion vector obtained by performing a block matching technique for the smaller region. The best motion vector for each region is selected according to a priority scheme and a predetermined threshold value. Adjacent regions having the same motion vector are then merged together, and a region shape representation routine is used to specify contour pixels that will allow the merged regions to be recovered by a decoder. A contour coding routine is then used to encode the contour pixels for transmission to the decoder. The present method requires less information about the motion field to be sent to the decoder and results in an improved prediction error compared to the H.261 standard currently used. The present invention is particularly advantageous for very low bit-rate applications. <MATH> |
