| 摘要 |
PURPOSE:To prevent the deterioration in the quality of a read picture by arranging a mark corresponding to a read start position of an original document at the outside of reading in the main scanning direction for an original picture and setting the star timing in the effective picture range in the subscanning direction based on the detection timing of the said mark. CONSTITUTION: In reading a picture of the original, when a line image sensor 8 reads a white picture WS of a width (a), a sample-and-hold circuit 24 is oeprated to sample the picture signal level corresponding to the white level at that time. Then the gain of the analog processing section 20 as a white balance level is set when the line image sensor 8 reads the picture of the original on a contact glass 1 as to the said line. Thus, the effect of the luminous quanity fluctuation of the light source 2 at the subscanning movement and the effect of the difference from the transmittivity of a color separation filter 6 are eliminated.
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