In order to improve print image quality, attribute information is generated for each pixel of a bitmap image generated according to a drawing command, and the bitmap image and attribute information are written in a memory. However, when this is done, data amount to be written in the memory increases, and the rasterize processing speed lowers. Hence, a display list is generated by interpreting PDL data, a bitmap image and attribute information of each pixel are rasterized based on the display list, and the bitmap image and attribute information are written in the memory. In this case, a black attribute is written in attribute information of an object filled with black, and the color value of that object is not written in the bitmap image.