| 摘要 |
PROBLEM TO BE SOLVED: To provide an image reading apparatus capable of reducing apparatus costs. SOLUTION: An image reading apparatus includes a traveling means that moves a document image reading position of an optical system guiding a document image to a line image sensor, reads a reference white image of a reference white plate provided on a moving route of the reading position through the line image sensor and performs shading correction for image reading. In such an image reading apparatus, the reference white plate comprises a density image, continuous to the reference white image, of a density different from that of the relevant reference white image and on the basis of a signal level outputted from the line image sensor when the reading position is moved over the reference white plate, a boundary between the reference white image provided on the reference white plate and the density image is discriminated. A coordinate value, on the moving route, of the discriminated boundary is set to an origin of the reading position. COPYRIGHT: (C)2009,JPO&INPIT
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