| 摘要 |
<p>PURPOSE:To improve the coding efficiency and to obtain picture quality preferred visually by applying threshold level processing with a larger threshold level toward higher order discrete cosine transformation coefficient in response to the transmission bit rate of the device. CONSTITUTION:The device consists of a discrete cosine transformation section 1 applying discrete cosine transformation a digitized picture signal or an inter- frame difference of the picture signal, a threshold level processing section 11 applying threshold level processing to a transformation coefficient being the output, a quantizing section 3 quantizing the transformation coefficient subject to threshold level processing, a variable length coding section 4 applying variable length coding to the quantized transformation coefficient, a buffer section 5 storing tentatively the transmitted code and deciding the quantization step width and a threshold level setting section 10 setting the threshold level based on the information. Then the threshold level is set larger toward the higher order discrete cosine transformation coefficient while the transmission bit rate and the buffer residual quantity are controlled. Thus, the coding efficiency is improved and a picture preferred visually is obtained.</p> |
