Patent Number: 6,307,970

Title: Search system for use in compression

Abstract: This disclosure provides a block-based compression system which uses avariable size search window, to thereby substantially reduce the timerequired for compression. In a MPEG-2 system, square tiles are processedleft to right in rows, beginning at the top of a frame and finishing atthe bottom. The absolute value of pixel differences for already-processed"northwest," "north," "northeast" and "west" neighbor tiles are separatelysummed and compared to a threshold. If any of the sums exceeds thethreshold or if any of the neighbor tiles are unavailable (e.g., the tileunder consideration is in the top row or the left-most column), then amaximum size search window is used to determine the tile's "closest match"in a prior image frame and the associated motion vector. If none of theexceed the threshold, then a relatively smaller size search window isused. The size of the smaller window is selected in dependence upon themotion vectors for the neighbor tiles, e.g., if the neighbor tiles havesimilar motion vectors and small residuals, the search for the "closestmatch" is performed in a relatively small area.

Inventors: Schuyler; Marc P. (Mountain View, CA), Wee; Susie J. (Mountain View, CA)

Assignee:

International Classification:

Expiration Date: 10/23/2013