| 摘要 |
<p>PROBLEM TO BE SOLVED: To maintain image quality high over an entire image, to make a code amount proper for each prescribed time interval and to attain high-speed processing with a small scale circuit. SOLUTION: A bit shift circuit 29 shifts a quantization coefficient which is obtained by a quantization circuit 28a by shift bit numbers m1-m4 to provide an output of 4 sift signals in parallel. Code amount calculation circuit 40a-40d calculate a coding amount by one image pattern, when the four shift signals are variable length coded to provide an output of plural code amount evaluation values b1-b4. A scaling coefficient update circuit 42 sets a scaling coefficient k2 in response to the evaluation values b1-b4 and supplies it to the quantization circuit 28b. A VLC circuit 36e stops coding when a code amount by one pixel block exceeds a calculated upper limit value for each pixel block, based on a signal amount of a DCT coefficient at an upper limit calculation section 46.</p> |
