The image processing device according to an aspect of the invention comprises an image input device for inputting image data representing a color image, a distance calculation device for calculating a distance on a color space between a noticed pixel of the inputted color image and each of peripheral pixels including the noticed pixel, a factor calculation device for calculating a weighting factor for each peripheral pixel in accordance with the calculated distance, and a weighted average processing device for calculating image data of the noticed pixel by obtaining a weighted average of image data of the peripheral pixels using the weighting factor calculated for each peripheral pixel.