| 摘要 |
PURPOSE:To prevent a decrease in the read level of image information due to shading correction by decreasing the reflection factor of a white reference original for shading correction by an increase in the intensity of reflected light. CONSTITUTION:An all-white original 3 set as a reference is set on the internal surface of original platen glass 1 and an original is set on the external surface of the original platen glass 1 while inverted. The original is lighted by light sources 2a and 2b and the reflected light 5 is guided to an optical system to form its image on a photoelectric sensor, so that image information is read out of the original. When the original is read, shading corrections for the distortion of the optical system and photoelectric sensor are made. The all-white original is close to the light sources, so the reflected light is intensified and an all-white signal obtained by converting the reflected light from the all-white original surface photoelectrically becomes intenser than when the all-white original is set outside the original platen glass because there is reflection on neither the external surface nor the internal surface of the original platen glass, so the reflection factor of the reference all-white original 3 is decreased as much as the influence. Consequently, the all-white signal obtained by said photoelectric conversion is utilized for the shading corrections as it is.
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