| 摘要 |
PROBLEM TO BE SOLVED: To provide a scanner using a gray reference board in which a gain can be controlled without lowering accuracy. SOLUTION: A white reference board 13 is read in advance, the gain of an amplifier circuit 16 is controlled to make the photoelectrically converted output of an image sensor 15 be the same value [W], and while keeping the gain of the amplifier circuit 16 as it is, a value [G] of the photoelectrically converted output from the image sensor 15 is measured by reading a gray reference board 14. Before really reading a document 12, the gray reference board 13 is read, the gain (value [A]) of the amplifier circuit 16 is found to make the photoelectric converted output of the image sensor 15 the said value [W], and a gain R=A×G/W in the real read of the document 12 is found. COPYRIGHT: (C)2003,JPO
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