Patent ID: 7102673

Claim:
A device comprising: a pixel portion having a plurality of pixels each comprising a photoelectric conversion element and a light emitting element; and means for determining a defective pixel, wherein the defective pixel is determined by the steps of: reading a first calibration sheet to obtain a first image signal of each of the plurality of pixels by using the photoelectric conversion element; reading a second calibration sheet to obtain a second image signal of each of the plurality of pixels by using the photoelectric conversion element; calculating a first difference between the first and second image signals of each of the plurality of pixels; obtaining at least a value selected from a modal value, an average value and a maximum value of the first difference of each of the plurality of pixels; and determining whether each of the plurality of pixels is the defective pixel by obtaining a second difference between the first difference of each of the plurality of pixels and the value selected from a modal value, an average value and a maximum value of the first difference of the plurality of pixels.