| 摘要 |
PURPOSE:To implement encoding processing without deteriorating picture quality by quantizing a picture data after orthogonal transformation in a prescribed quantization step so as to obtain a generated code quantity and deciding a new quantization step based on the generated code quantity and the residual amount of a transmission buffer. CONSTITUTION:A picture data read for each block by frame memories 1, 31 and 2, 32 is subject to orthogonal transformation by an orthogonal transformation device 33. The obtained data is given to a quantization device 34, in which the data is subject to 1st quantization while a quantization is kept constant. Then a new quantization step is decided based on the residual amount of the transmission buffer and the total sum of the generated code quantity to quantize the picture data again. According to the method, even a picture signal requiring detail such as an expression of a portrait is coded with stable picture quality. |
