| 摘要 |
PROBLEM TO BE SOLVED: To easily set respective amplification factors in the case of respectively amplifying R, G and B signals from an image reading sensor. SOLUTION: The RGB signals, which are provided by reading a standard white board through an image reading part 201-3, are respectively amplified by amplifiers inside analog processing circuits 118-120. The amplification factors of respective amplifiers can be set to three stages of standard and±α, first of all, the factor is set to the standard and the quantity of light, with which this white board is irradiated, is adjusted so that the output of the amplifier for any signal getting an intermediate level among the RGB signals at that time can be a prescribed value. Afterwards, the amplification factors of respective amplifiers for remaining two signals are set to the maximum without saturating the respective amplified outputs so that the levels of RGB signals can be uniformly adjusted.
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