Patent ID: 8324551

Claim:
An image reader comprising: a sensor substrate having photodetectors with filters which are disposed in a plurality of lines with different wavelengths in a conveyance direction of an illuminated body to be conveyed, the photodetectors being disposed at a substantially equal pitch in a read width direction linearly for the respective photodetectors with the filters of the same wavelength; a pixel detecting circuit for measuring photoelectric conversion output values of the photodetectors by setting a desired threshold range, for specifying a photodetector with a photoelectric conversion output value less than the desired threshold range, and for detecting a pixel position of the specific photodetector; a pixel correcting circuit for generating a corrected output value by calculating output value data corresponding to the pixel position of the photodetector specified by the pixel detecting circuit, and for passing photoelectric conversion output signals of the photodetectors; first calculation means for calculating an output value from the photoelectric conversion output value of a photodetector adjacent to the specific photodetector in the read width direction; and second calculation means for calculating a ratio between a first value and a second value, the first value being an output value of the photodetector disposed in the conveyance direction with respect to the specific photodetector, and the second value being a photoelectric conversion output value of a photodetector adjacent, in the read width direction, to the photodetector disposed in the conveyance direction with respect to the specific photodetector, wherein the pixel correcting circuit multiplies the values obtained by the first calculation means and the second calculation means, substitutes the product for the output value at the pixel position of the photodetector specified by the pixel detecting circuit, and outputs, as a line output, the substitute together with output values at pixel positions of the photodetectors not specified by the pixel detecting circuit.