An image processing apparatus comprises: a division unit configured to divide an input image into a plurality of color regions based on a color difference; a color gradient information calculation unit configured to calculate color gradient information at a boundary between the divided color regions from color information of the input image; an attribute determination unit configured to determine a gradation attribute representing a characteristic of a color gradient at the boundary using the color gradient information; and a vectorization target determination unit configured to determine, based on the gradation attribute of the boundary determined by the attribute determination unit, whether the input image is a vectorization target.