Each of a plurality of image reading units reads an image of an original and outputs image data. An image processing unit performs an image processing on the image data based on either one of a read characteristic of the image data and a parameter set according to the read characteristic of the image data. A storing unit stores therein the image data. A printing unit prints the image data processed by the image processing unit. A communication unit exchanges the image data stored in the storing unit with other image forming apparatus for sharing printing of the image data.