Efficient coding of the classification table in low bit rate subband image coding by use of hierarchical enumeration

A new method for lossless coding of the classification table in low bit rate subband image coders with block-wise classification is proposed. The method is referred to as hierarchical enumeration and uses an algorithmic enumeration technique to associate a fixed-length unique binary codeword with each possible combination of integers defining the classification table. The resulting bit rate is less than the first order entropy of the classification table. When using hierarchical enumeration in combination with pyramid vector quantization of the subband samples, a high performance image coder using only fixed-length codewords is obtained. The proposed coder compares favorably with state-of-the art image coders using variable-length coding