An image processing apparatus includes: a dispersion calculation unit for calculating a dispersion of pixel values in each of a plurality of pixel groups which are each composed of a pixel of interest and peripheral pixels around the pixel of interest in an image and in which the pixel of interest and the peripheral pixels are arranged in directions different from one another; and a gradation determination unit for determining whether or not the pixel of interest belongs to a gradation region on the basis of a magnitude relationship among the dispersions calculated by the dispersion calculation unit.