| 摘要 |
PROBLEM TO BE SOLVED: To provide an image scanner capable of reading out a plurality of sheets of both side document in a short time under a state free from image quality deterioration. SOLUTION: In case of a both side document, an automatic document carrier performs browsing and document image data is read into a memory (step S8) while correcting the document surface image data line by line based on shading correction coefficients obtained at step 3. Subsequently, an operation for reversing the document is carried out in order to read out the rear surface of the document (step 9). When the document is reversed, a CPU moves a first mirror unit beneath a reference whiteboard, reads out a line of shading correction data, and moves the first mirror unit beneath a browsing document glass (step S11) after operated shading correction coefficients are set in a coefficient memory in a shading correction circuit (step S10). In other words, when a both side document is under carriage by means of the automatic document carrier, the shading correction coefficients are updated at such a timing as the document is reversed after it is read out. COPYRIGHT: (C)2004,JPO&NCIPI
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