Background separation/filtering for videophone applications

To increase efficiency on interframe coding and/or to preserve speaker privacy for videophone applications, a method for real-time background separation based on stereoscopic range finding is developed. The algorithm includes foreground center extraction, foreground threshold calculation, occlusion-free direct block matching with quadtree block subdivision, and contour segmentation using a motion edge. The algorithm is evaluated using a stereo-video sequence. For an application using the background separation technique, background filtering is introduced. Background filtering can decrease the number of inessential coded blocks, when applied to a motion-compensated hybrid differential pulse-code modulation (DPCM)/transform coder. If the cut-off frequency for filtering characteristics is further lowered, the filtering will conceal details in the background