| 摘要 |
PURPOSE:To prevent a reproduced picture from being degraded by controlling a quantization step while deciding the character corresponding to a block composed of the plural picture elements of an input picture signal. CONSTITUTION:A discrete cosine transformation part 1 executes discrete cosine transformation to the input picture signal or to an inter-frame difference signal. A quantization part 2 quantizes a transformation coefficient from the transformation part 1 or the inter-frame difference signal of this transformation coefficient. On the other hand, the quantization part 2 is equipped with constitution for switching the quantization step, and the switch is controlled by a picture deciding part 4. Namely, corresponding to the block of the input picture signal, the quantization step is switched while deciding that the block is corresponding to any of flat part such as sky or walls, edge part such as the contour of an object or fine pattern part such as a design. An encoder part 3 executes variable length encoding such as Huffman encoding or the like to a quantized output signal. |
