Patent ID: 8041131

Claim:
A method of operating an encoding apparatus to compress image data, the method comprising: accepting quantized transform coefficients of one or more blocks of image data into the encoding apparatus; for a first region of an ordered series of quantized transform coefficients of a block of image data, the first region possibly including the whole series, the series having a most likely-to-occur amplitude, and at least one other amplitude including a next-to-most likely-to-occur amplitude, the encoding apparatus encoding the position and amplitude of each cluster of consecutive coefficients having amplitude other than the most likely-to-occur amplitude, the encoding of each cluster including the encoding apparatus encoding one or more events for the cluster, including encoding a joint event defined by at least two parameters: the number of coefficients having the most likely-to-occur amplitude preceding the cluster, and the number of coefficients in the cluster, and encoding an indication of the number of trailing coefficients having the next-to-most likely-to-occur amplitude in the cluster, the encoding of the events by the encoding apparatus forming event codewords, with the encoding of each cluster according to at least one multi-dimensional joint encoding mapping such that for at least some events, encoding the events by the joint encoding mapping is such that on average, the more likely an event is to occur, the shorter the event codeword formed to encode the event; and the encoding apparatus encoding the amplitude of the coefficients that have amplitude other than the most likely-to-occur amplitude and that are not jointly encoded by the encoding of the indication of the number of trailing coefficients in the cluster, the encoding of the amplitude by the encoding apparatus forming amplitude codewords.