Edge enhancement processing is executed by obtaining a sum of whiteness degrees around a target pixel, to which edge enhancement is to be applied, and by adjusting the amount of edge enhancement such that the degree of edge enhancement decreases as the sum of whiteness degrees increases, and the degree of edge enhancement increases as the sum of whiteness degrees decreases. A whiteness degree is a value indicating the extent to which a pixel is close to white, and a sum of whiteness degrees indicates the extent to which the color around the target pixel is whitish.