JOINT AMPLITUDE AND POSITION CODING FOR PHOTOGRAPHIC IMAGE AND VIDEO CODING

A method, apparatus, and carrier medium to encode a series of quantized transform coefficients. The method includes identifying clusters of at least one non-zero-valued coefficients, and for each such cluster, identifying at least one position event that defines the relative position and runlength of the cluster of non-zero coefficients and any intervening run of zero-valued coefficients, and identifying at least one amplitude event to define the amplitudes of the non-zero-valued coefficients in the identified cluster. The method further includes jointly encoding the identified position event or events with the identified amplitude event or events such that relatively short codewords are formed to represent values or sequences of values that are relatively more likely-to-occur, and relatively long codewords are formed to represent values or sequences of values that are relatively less likely-to-occur. The method is applicable to encoding a region in the series where there is likely to be a cluster of non-zero-valued coefficients.