An image transformation apparatus for performing a transformation processing for outputting a color image by an image output device such as a color printer. The image transformation apparatus has an image receiving section for receiving an image represented by digital data, an image sort discrimination section for discriminating whether the image received by the image receiving section is a halftone dot image or a multiple gradation image, an image transformation section for applying a conversion processing for the multiple gradation image to the halftone dot image when it is decided by the image sort discrimination section that the image received by the image receiving section is the multiple gradation image, and a driver section for outputting an image discriminated as the halftone dot image by the image sort discrimination section and an image converted into the halftone dot image by the image transformation section to an image output device.
