A limited output color group generation section generates in advance, from a group of input colors (limited input color group) satisfying a constraint condition set in an input color space in advance, a group of output colors (limited output color group) in an output color space corresponding to the input colors. An input color element determination section determines at least one element of input colors satisfying the constraint condition using the limited input color group and the limited output color group. Since the limited input color group and the limited output color group satisfy the constraint condition, at least one element of the input colors satisfying the constraint condition can be determined easily.