| 摘要 |
PROBLEM TO BE SOLVED: To provide an image reading apparatus capable of reading an original image precisely by suppressing fluctuation in reading level of the original image. SOLUTION: A main scanning distribution abnormality deciding part 115 acquires a ratio between maximum value and minimum value in the main scanning direction of an acquired reference white board actual measurement value data, and uses the value to decide the presence or absence of main scanning distribution abnormality. A corrective calculation part 118 calculates reference white board corrective value data. A shading interval determining part 119 acquires a ratio between the reference white board actual measurement value data obtained last time and the reference white board corrective value data, and compares the value with a threshold value. Based on the result, whether to start the next shading operation or not is determined. A shading output switching part 120 outputs the reference white board actual measurement value data at shading operation while outputs the reference white board corrective value data at non-shading operation, to a shading correction circuit 102. COPYRIGHT: (C)2008,JPO&INPIT
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