An image forming apparatus includes plural input filter sections controlling different types of input-processing performed by corresponding input devices to produce respective input image data sets each having a different input format, plural output filter sections controlling different types of output-processing performed by corresponding output devices that receive respective output image data sets each having a different output format, and an image processing section being made sharable by any given one of the input filter sections and any given one of the output filter sections, and converting an image data set from an input format of the one of the input filter sections to an output format of the one of the output filter sections.