Adjustment object color space containing movement source partial color space including a color of an object of conversion processing and movement destination partial color space including a color in which the conversion processing is performed so as to inscribe the spaces is handled as a conversion object region. The inside of the conversion object region is moved toward a target color so that coordinates of an adjustment object overlaps with coordinates of a point after movement and the boundary of a movement region moves little or does not move at all. As a result of this, a phenomenon such as a color jump or gradation inversion occurs little in the boundary portion to the outside of an adjustment object region. Therefore, maintenance of gradation continuity of an image of a color adjustment object and prevention of color inversion can be combined to make partial color adjustment.