COMPRESSION METHOD FOR DIVIDING EVERY WORD AND APPLYING COMPRESSION TO MOST SIGNIFICANT BIT

摘要

PROBLEM TO BE SOLVED: To attain high compressibility of a compression device by dividing an original word having plural bits into most and least significant bits, compressing the least significant bits by a loss compressor and combining the most significant bits with the compressed least significant bit. SOLUTION: When a single code word 31, for example, is divided into three most significant bits(MSBs) 32 and five least significant bits(LSBs) 33, only the bits 33 are compressed. Then bits 0 to 4 are sent to a loss compressor (hierarchical vector quantization(HVQ) encoder) 35 and bits 5 to 7 are not sent anywhere. Both channels are compressed by means of an LZ encoder 34 having no loss and outputted to a decoder. Even under such conditions, both channels are restored by an LZ decoder. Meanwhile, only the bits 33 are decoded by an HVQ decoder. Then two parts which are generated as the results undergo the exclusive OR and are inputted to a coding reference table.