| 摘要 |
PROBLEM TO BE SOLVED: To enhance precision of shading compensation in an image reader. SOLUTION: A standard plate 130 is stored in a place other than a document carrying path. During shading compensation, the standard plate 130 is attached, a datum level 136 becoming a chromatic reference is read out and shading compensation is performed. In other word, the distance between the document surface (upper surface) of a document P and a CIS head 110 when the document P is read out is made to coincide with the distance between the datum level 136 of the standard plate 130 and the CIS head 110 during shading compensation. They are a predetermined distance T, i.e. the focal length of the CIS head 110. Consequently, precision of shading compensation is enhanced and shading can be compensated accurately. COPYRIGHT: (C)2007,JPO&INPIT
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