| 摘要 |
PURPOSE:To surely perform automatic gain control by providing the first white area and the second white area of the same color. CONSTITUTION:A glass plate 21 is provided with an L-shaped white reference plate 26 whose rear face a white reference color is painted on. White balance correction, shading correction, and AGC are performed in the first white area 26a of the white reference plate 26 before read of an original 22 is started, and AGC is performed in the second white area 26b of the white reference plate 26 at the time of subscanning to read the original 22. Consequently, AGC is stably performed by the reflected light from the first white area 26a and the second white area 26b at the time of subscanning even if the quantity of light of a light source 23 is changed during read of the original 22 to change a read picture signal.
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