| 摘要 |
PROBLEM TO BE SOLVED: To provide an image reader highly accurately detecting dust on a reader by minimizing the effect of density variation or warping at a white member, in spite of a configuration where the inexpensive white member is used for a counter face of an image sensor. SOLUTION: The present invention relates to the image reader wherein a member that becomes a white reference and a white member are disposed on a face counter to a reading means that reads a document image, and the reader comprises: a threshold calculating means (S311) for calculating a threshold on the basis of data multiplying data (S308) reading the white member by the reading means by a shading correction coefficient and a white member reading correction coefficient; and a foreign substance mixture determining means for determining foreign substance mixture by comparing the data multiplied by the shading correction coefficient and the white member reading correction coefficient, with the threshold calculated by the threshold calculating means. COPYRIGHT: (C)2009,JPO&INPIT
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