1. A printer driver for an image forming apparatus comprising: a user interface to specify a condition for converting component data of a plurality of printing colors into component data of a multi color in which a special color different from the plurality of printing colors is added to the plurality of printing colors; and a notification part to notify the image forming apparatus to convert the component data of the plurality of printing colors from the image processing part into the component data of the multi color to the image forming part based on the condition of the user interface and thereby form an image made of a plurality of pixels by using the plurality of printing colors and the special color.