1. An image processing apparatus, comprising: an image region determining unit configured to determine a colored region where an inside of an outline is filled with a single color from color image data; an image color determining unit configured to determine a color of the colored region determined by the image region determining unit; and a change processor configured to change the colored region determined by the image region determining unit to a patterned region with a pattern different in each of the colors determined by the image color determining unit.