| 摘要 |
PROBLEM TO BE SOLVED: To assign a code amount to allow the user not to feel visual image quality deterioration. SOLUTION: In the case that the coder is configured with a block processing section 102 applying block processing to received image data, an orthogonal transformation section 103 applying orthogonal transformation to the block- processed image data, control sections 104, 105, 109, 110 controlling a quantization step quantizing the block image data transformed by the orthogonal transformation section 103, and a quantization section 106 quantizing the block image data converted by the orthogonal transformation section 103 based on the quantization step controlled by the control sections 104, 105, 109, 110, the control sections 104, 105, 109, 110 divide the block image data subject to orthogonal transformation by the orthogonal transformation section 103 into plural areas. Then the control sections control the quantization steps based on the orthogonal transformation coefficients in the prescribed area among the plural areas. |
