Patent ID: 8131096

Claim:
A method of operating processing hardware, the method comprising: (a) accepting image data represented by an ordered series of digital signals representing a block of quantized coefficients of a transformed block of image data, the signals each having a respective value, including a respective amplitude from a finite set of amplitudes consisting of a most likely-to-occur amplitude and at least one other amplitude, the at least one other amplitude including a second-most likely-to-occur amplitude; (b) using a position event identifying method executing on the processing hardware to identify position events that each include a cluster of at least one consecutive signal having any amplitude other than the most likely-to-occur amplitude, such that the position events define the positions and runlengths of the clusters and of any intervening runs of consecutive signals having the most likely-to-occur amplitude; (c) using an amplitude event identifying method executing on the processing hardware to identify amplitude events defining the amplitudes of the signals having amplitudes other than the most likely-to-occur amplitude; and (d) encoding the identified position events, the identified amplitude events, and the signs of the amplitudes other than the most likely-to-occur amplitude in the identified amplitude events, such that for at least some of the identified position events and identified amplitude events, events containing a cluster of signals having more likely-to-occur signal amplitudes other than the most likely-to-occur amplitude are each encoded by a concatenation of one or more codewords that is shorter than the concatenation of the one or more codewords that encodes at least one event containing a cluster of signals having less likely-to-occur signal amplitudes other than the most likely-to-occur amplitude; and (e) outputting the codewords formed by the encoding, wherein the position event identifying method uses 2-D Cluster Length and Position Identifying, 2-D Cluster Length and Position Identifying including identifying position events that each includes a run of one or more consecutive signals having other than the most likely-to-occur amplitude preceded by either no signals having the most likely-to-occur amplitude, or a run of one or more consecutive zero-valued signals having the most likely-to-occur amplitude, each position event identified by the runlengths of the preceding run of consecutive zero-valued signals having the most likely-to-occur amplitude, including a runlength of 0, and the runlength of the run of consecutive signals having other than the most likely-to-occur amplitude.