Patent ID: 8848225

Claim:
An image forming apparatus for outputting a plurality of sets of output units, each output unit that is composed of a plurality of pages with a determined order being one set, and the apparatus comprising: an image forming unit for successively forming respective images corresponding to the plurality of pages on a plurality of sheets; a control unit for performing an arithmetic processing of an image eigenvalue calculated with a part of the image excluded for each output unit; a first storage for storing a result of the arithmetic processing performed for one specific set out of the plurality of sets of output units; and a second storage for storing a result of the arithmetic processing performed for an nth set out of the plurality of sets of output units; wherein the control unit determines whether or not the images are normally formed on the plurality of sheets for the nth set based on a comparison result between the result of the arithmetic processing stored in the first storage and the result of the arithmetic processing stored in the second storage.