| 摘要 |
PURPOSE:To obtain good picture quality by suppressing quantizing distortion small for the important coefficient of high level, and besides, to suppress the data quantity of a processing unit consisting of plural blocks below the prescribed data quantity precisely by a fewer steps compared with a device in the past. CONSTITUTION:A blocking circuit 12 divides picture data into blocks in which one block consists of nXn-piece in spatial arrangement. A DCT circuit 13 discrete-cosine-transforms the picture data of each block, and calculates a transformation coefficient. Quantizers Qm have quantization widths different from each other, and quantize respectively the transformation coefficients. An area determination circuit 14e detect an area in which the transformation coefficient over a prescribed threshold is contained on the basis of the absolute value of the transformation coefficient Cij. A control circuit 14f controls the quantizer Qm so as to quantize the transformation coefficient in the above area by the quantization width smaller than that of the transformation coefficients in other areas. |
