| 摘要 |
An image scanning device includes an image sensor obtaining an analog image signal; a variable gain amplifier amplifying the analog image signal; an analog-to-digital converter converting the amplified analog image signal into digital image data; a highest value detection unit detecting the highest value in the digital image data; and an amplifier gain setting unit setting an amplifier gain of the variable gain amplifier. The amplifier gain setting unit initially sets the amplifier gain of the variable gain amplifier such that the highest value in first digital image data of a reference image falls within a predetermined range, and if the highest value in second digital image data of the reference image obtained with the initially-set amplifier gain exceeds the predetermined range, the amplifier gain setting unit decreases the amplifier gain of the variable gain amplifier.
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