1. An image reading apparatus comprising: a plurality of line sensors mutually spaced in a sub scanning direction to scan an original in the sub scanning direction; a platen arranged between the original and said plurality of line sensors; a mover moving said platen at a rate relative to said plurality of line sensors, said rate being different from that of the original relative to said plurality of line sensors; a first extractor extracting from each of a plurality of data output from said plurality of line sensors a first feature pixel having a predetermined feature of a first level; a second extractor extracting from each of said plurality of data a second feature pixel having said predetermined feature of a second level; and a detector comparing said plurality of data corresponding to a single location on the original to detect said first feature pixel extracted from one of said plurality of data, as a noise pixel if said second feature pixel is not extracted from each of said plurality of data other than said one of said plurality of data.