VARIABLE LENGTH CODING FOR CLUSTERED TRANSFORM COEFFICIENTS IN VIDEO COMPRESSION

Coding quantized transform coefficients as occur in image compression to form codewords, and decoding a bitstream comprising the codewords. The coding combines a position identifying method to identify the relative position of clusters of consecutive non-zero-valued quantized transform coefficients, an amplitude event identifying method to identify amplitude events in the clusters of non-zero-valued quantized transform coefficients, and a coding method to code the position events, amplitude events, and signs of the amplitudes in the clusters. The coding method is particularly applicable to an ordered series of quantized transform coefficients where clusters are likely-to-occur.