WAVELET-BASED IMAGE ENCODING AND DECODING DEVICE AND ENCODING METHOD AND DECODING METHOD

摘要

[PROBLEMS] To provide an encoding device capable of achieving a sufficient compression ratio even when using a prefix code such as a Huffman code as the entropy encoding method in the wavelet conversion encoding. [MEANS FOR SOLVING PROBLEMS] All the components of LH, HL, HH sub-band coefficients of the same hierarchy and the same space coordinate are extracted as a set from a wavelet sub-band space. Furthermore, it is judged whether each component of each coefficient is zero and as 1-bit judgment result, the respective judgment results are combined to obtain multibit flag information. Upon encoding, firstly, the Huffman information is subjected to variable-length encoding by the Huffman encoding code. After this, only the coefficient values which are not zero are similarly subjected to the variable-length encoding by the Huffman code or the like and outputted.