IMAGE CODING AND TRANSMITTING DEVICE AND METHOD HAVING SCALABILITY AND REQUANTIZATION METHOD

摘要

PROBLEM TO BE SOLVED: To reduce the deterioration of picture quality that is caused by the requantization by providing a constitution where a code converter recognizes the comparison result of an encoder from the identification information inputted from an identification information generation means of the encoder and a requantization means of the code converter quantizes the inverse quantization coefficient corrected by a correction means with the requantizing quantization width. SOLUTION: An encoder 100 compares a DCT coefficient with an inverse quantization coefficient and generates the identification information according to the comparison result. This identification information is inputted to a code converter from the encoder 100 and accordingly the relation between the DCT coefficient that is not quantized yet by the encoder 100 and the inverse quantization coefficient can be recognized from the identification information when the requantization is carried out by the code converter. As a result, the encoder 100 can correct the inverse quantization coefficient and the error due to the requantization can be reduced. A correction part 133 inputs the inverse quantization coefficient via an inverse quantizer 115 and then inputs a rounding flag via a decision part 131.