An image processing system of this invention includes a variation calculator for calculating a variation in pixel value of each pixel relative to adjacent pixels, and an edge degree calculating device for calculating, for one arbitrary pixel, an edge degree which expresses numerically a probability of the one pixel being an edge, based on variations of a peripheral pixel group consisting of the one pixel and surrounding pixels. According to the image processing system constructed in this way, whether edges or not can be evaluated with high accuracy even when the pixels undergoing noise.