A pixel value change processing section corrects the value of a current pixel in an input image so that the size of a code produced by a coding processing section is reduced, and outputs a changed pixel value. When predictive coding is employed, the pixel value change processing section outputs the same pixel value as that which is predicted by a predictor. When arithmetic coding is employed, the pixel value change processing section outputs a pixel value at which a dominant symbol is obtained in the arithmetic coding. The coding processing section produces a code from the changed pixel value 310. The pixel value change processing section produces an error value between the current pixel value and the changed pixel value. An error distribution processing section produces an error distribution value from the error value and adds the error distribution value to the pixel value of the input image.