| 摘要 |
PROBLEM TO BE SOLVED: To securely shorten a wait time of an image reader in a power-off state or during recovery from a power-saving mode while setting the gain of an amplifier to a proper value. SOLUTION: The amplification factor of the amplifier which amplifies an analog image signal obtained by reading a document image is set based on a read signal of a white reference plate when a main power source is turned on. Each time a document is scanned, data for shading correction are generated from data of the white reference plate to perform shading correction. A peak value of the latest data for shading correction is always held. During recovery from a standby mode, the gain of the amplifier is corrected so that the saved peak value coincides with a white level target value. Thus, the proper gain can be set again without performing mechanical operation, and the wait time can be shortened. COPYRIGHT: (C)2008,JPO&INPIT
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