Quantizing apparatus and quantizing method

摘要

A difference signal generated in a prediction encoding process is block-segmented by a block segmenting circuit 2. Thus, the level distribution of the block-segmented difference signal is concentrated to a narrower portion than the level distribution of one entire screen. Reference values DR and MIN of each block of the difference signal are detected. A quantizing step width DELTA and shift data DELTA S are determined corresponding to such reference values and the number of quantizing bits N. A quantizing circuit 6 quantizes the difference signal with DELTA . The difference signal is shifted and quantized so that the level 0 of the difference signal is obtained as 0 on the decoding side. A flag FLG and a that represent the quantized value of the level 0 are transmitted as side information along with the quantized value Q.