Patent ID: 7697175

Claim:
An image reading apparatus comprising: at least three line sensors having corresponding filters that differ in spectral sensitivity, the at least three line sensors being arranged in a subscanning direction with a distance therebetween to scan an original in the subscanning direction and generating at least three corresponding signals based on the scanning of the original, wherein the signals of the at least three line sensors are composited together by the image reading apparatus to generate an image corresponding to the original; a platen arranged between a movement pathway of the original and said at least three line sensors; a mover moving said platen at a rate relative to said at least three line sensors, said rate being different from a movement rate of the original relative to said at least three line sensors; a noise pixel detector detecting a noise pixel corresponding to contamination on said platen, wherein said detecting is made based on time dependent variations between said at least three signals due to the different relative rates of movement of the platen and the original; a color detector detecting a color of each noise pixel from said at least three signals; and a determiner validating a result of detection for a noise pixel by said noise pixel detector when a color of said noise pixel and that of a pixel neighboring the noise pixel form a predetermined combination.