| 摘要 |
PURPOSE:To obtain an optimum image data even when it is different from the reference white board of an original by deciding a correcting shape for shading by data read from the reference white board and setting the surface density of the image data with reading a image at the point end part of the original. CONSTITUTION:While the reference white board 11 is scanned, the white peak level of reading data is sampled with making a switch SW1 on by a peak sampling signal SP and is given to an A/D converter 14 as a reference voltage. At the same time, shading data are written to a RAM for the shading and the correcting shape for the shading is stored. At a timing just prior to the scanning of the point end of an original 2, the switch SW1 is again made on by the peak sampling signal SP and the white peak level (the surface level of the original 2) of the reading image at the point end of the original 2 is sampled and is outputted to the A/D converter 14 as the reference voltage of an original surface.
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