| 摘要 |
PROBLEM TO BE SOLVED: To obtain an image reader that suppresses deterioration of an outputted image caused by a defective photodetector. SOLUTION: When white reference data Dw, proper to pixel data stored in a white reference storing part 21, is compared with a prescribed reference value and it surpasses the reference value, pixel data Dn from an A/D converting part is entered to a subtraction circuit 23, where a difference Dn-Dk between the data Dn and black reference data Dk of a black reference storing part 22 is calculated. Next, a division circuit 24 divides an output Dn-Dk from the circuit 23 by the data Dw proper to the pixel data to calculate compensated data Dn'. The data Dn' is stored in a register 25 and also outputted to a gamma-compensating part, whereas when the data Dw proper to the data Dn stored in the part 21 falls below a prescribed reference value, the data Dn' stored immediately prior to the register 25 is outputted to the gamma compensating part again.
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