If a drawing section does not support the alpha blending drawing, or the bit depth of a first bitmap image is less than that of the alpha blending value, the alpha blending drawing is unavailable. To solve the problem even in such cases, a data processing method for a print controller and drawing controller, which is provided with a drawing section for executing drawing according to an input drawing command to a first bitmap image and a drawing process specifying section for performing alpha blending specification (transparency degree specification) for executing drawing according to an input object as a drawing command to the first bitmap image, includes an alpha value replacing section for replacing the alpha blending specification with area information corresponding to an alpha value and a drawing command converting section for converting the drawing command into another drawing command for performing a process corresponding to the area information.