An image forming apparatus stores raster image data corresponding to a background in a compressed format and generates intermediate data corresponding to a foreground of the background based on obtained print data. A decompressor decompresses the raster image data stored in the memory device and a rasterizer generates new raster image data based on the raster data corresponding to the background obtained by the decompression and the generated intermediate data corresponding to the foreground. When a request is made to stop the generation of the new raster image data in a state of waiting for at least a portion of the raster image data corresponding to the background to be decompressed, the rasterizer stops generation of the new raster image data, and the decompressor continues decompressing the at least a portion of the raster image data corresponding to the background.