1. An image reading apparatus comprising: a plurality of line sensors having filters different in spectral sensitivity, and mutually spaced in a sub scanning direction to scan an original in the sub scanning direction, wherein data of the plurality of line sensors are composited together to form an image of the original; 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 a rate of movement of the original relative to said plurality of line sensors; an extractor configured to extract a feature pixel having a predetermined feature from any of the plurality of data corresponding to said plurality of line sensors; a saturation detector obtaining saturation of a pixel from the plurality of data corresponding to said plurality of line sensors; and a detector configured to identify a noise pixel by comparing said plurality of data corresponding to a single location on the original and identifying the feature pixel as noise pixel if said feature pixel is detected for one of said plurality of data and is not detected as a feature pixel from each of the other said plurality of data and said feature pixel also has saturation of at least a predetermined value.