| 摘要 |
<p>PURPOSE:To set the code amount of an image, in which the block of a large density change and the block of a small density change appear while being mixed, at a stable value. CONSTITUTION:Image data Di for each processing block are transmitted to a quantizing means 4 after receiving orthogonal transformation at an orthogonal transforming means 3. The quantizing means 4 quantizes the orthogonally transformed data based on quantizing step width QP and transmits the quantized data to a run length data transforming means 5. The transforming means 5 outputs run length data S5 to a variable length coding means 6 and a zero time number calculating means 21. Based on the S5, the zero time number calculating means 21 calculates a zero appearance time number ZO and impresses it to a code amount control means 22 as the parameter of code amount control. The code amount control means 22 inputs a code amount B outputted from the variable length coding means 6 and the ZO, sets the QP adapted to the fluctuation of an image density change amount and applies it to the quantizing means 4. Thus, picture quality is made uniform between the image blocks.</p> |
