A touch screen displays a plurality of images corresponding to a plurality of colors represented by color information stored in a color information storage unit. A selection part indicating whether the image is in a selected state or an unselected state is associated with each image displayed on the touch screen. An intermediate color calculating unit calculates color information representing an intermediate color of two colors indicated by images respectively corresponding to two selection parts in the selected state. An intermediate color adding unit displays on the touch screen an image corresponding to the intermediate color, based on color information of the intermediate color calculated by the intermediate color calculating unit, and a selection part corresponding to the image. An output unit outputs the color information of the intermediate color corresponding to the selection part if the selection part corresponding to the intermediate color is selected.