Display control means displays, on display means, an image based on first conversion target image data in which color information is set for each of a plurality of image elements. Coordinate determination means determines a first coordinate in accordance with an instruction performed by using the pointing device. Conversion target condition setting means obtains color information of an image element, in the first conversion target image data, which corresponds to the first coordinate, and sets a first conversion target condition in accordance with the obtained color information. Color conversion means performs color conversion processing of changing color information of an image element, in the first conversion target image data, which satisfies the first conversion target condition, and displays an after-conversion image on the display means.