Patent ID: 7782503

Claim:
An image reading apparatus that reads an image from a document being simultaneously fed on an original plate, the apparatus comprising: a document feeder unit that feeds the document on the original plate; a first image reading unit that reads an image from the fed document at a first document-read position on the original plate; a second image reading unit that reads an image from the fed document at a second document-read position located at a predetermined distance from the first document-read position in a document feeding direction; a first detection unit that detects an independent pixel group in the image of the document read by the first image reading unit, the independent pixel group detected by the first detection unit comprising a plurality of pixels arranged consecutively in the document feeding direction; a second detection unit that detects an independent pixel group in the image of the document read by the second image reading unit, the independent pixel group detected by the second detecting unit comprising a plurality of pixels arranged consecutively in the document feeding direction; and a determination unit that determines the independent pixel groups to be abnormal if the independent pixel groups detected at the same main-scanning location by the first detection unit and the second detection unit have a positional difference in the sub-scanning direction that is larger than the predetermined distance between the first image reading unit and the second image reading unit in the document feeding direction.