| 摘要 |
PROBLEM TO BE SOLVED: To reduce block-like distortion (pseuds contour) generated in a decoded image by reducing the information quantity of a mean value signal and a deviation signal when the deviation of a pixel signal in a block exceeds a prescribed threshold and increasing information quantity to be allocated to a bit plane information signal to be generated. SOLUTION: A signal judging device 12 finds out the deviation of a pixel signal in a block and judges whether the deviation exceeds the prescribed threshold or not, and when the deviation of the pixel signal in the block exceeds the prescribed threshold, information quantity reducing devices 13, 14 respectively reduce the information quantity of a mean value signal and that of a deviation signal. A gradation reducing processors 15, 16 reduce the information quantity of the pixel signal in the block based on the mean value signal and the deviation signal and respectively generate bit plane information signals to which these information quantity values are allocated. A selector 17 inputs a selector signal, and when the deviation of the pixel signal in the block exceeds the prescribed threshold, selects the bit plane information signal generated by the processor 16. |
