METHODS AND APPARATUS FOR SCAN BLOCK CACHING

A method and apparatus for comparing portions of data from a digital raster signal to a plurality of scan blocks of data, where each scan block in the plurality describes either a defined image area or entire image frame is disclosed. Included are a hashing function that calculates hash codes for spatially-defined segments of an incoming raster signal; a recent scan hash table containing hash codes for scan blocks received within a specified time period; a comparator for comparing calculated hash codes for the spatially-defined segments of the incoming raster signal with hash codes stored in the recent scan hash table; a pixel capture and timing module for capturing a digital raster signal; and an output selector for selecting for transmission a compressed form of a scan block, a hash code index, or no data if a scan block exists in a remote frame playout buffer.