IMAGE FORMING APPARATUS, IMAGE FORMING SYSTEM, COMPUTER READABLE MEDIUM STORING PROGRAM AND IMAGE FORMING METHOD

An image forming apparatus includes a detecting unit that detects a size of a document, a scanning unit that scans a document image on the basis of the document size detected by the detecting unit, a storage unit that stores a plurality of image data pieces regarding the document image scanned by the scanning unit, an adding unit that adds, to the image data stored in the storage unit, data to convert an area corresponding to a difference between a size of a printing sheet and the size of the document, into predetermined image, and an image output unit that outputs image data to which data to convert an area corresponding to the difference between the printing sheet size and the document size into predetermined image, has been added by the adding unit onto a printing sheet of a designated size.