| 摘要 |
PURPOSE:To obtain a clear color picture by giving a reading mode function to make a reflectance ratio corresponding to the maximum gradation by 85%, to a gain control circuit or a distortion correction circuit. CONSTITUTION:The reading mode function, in which an original is read by making the reflectance ratio of 85% by the maximum signal level, is given to the gain control circuit 3 or the distortion correction circuit 5, and the reading of the color picture is performed by switching the reading mode. Namely, when a picture reading is performed by the reading mode, which makes the reflectance ratio of 100% be the maximum gradation cusomarily, a controlling part 6 gives, for instance, the value of A to the control circuit 3, and when the picture reading in which the reflectance ratio of 85% is the maximum gradation, is performed, the controlling part 6 gives the value of A/0.85 i.e., 1.18A to the gain control circuit 3. The gain control circuit 3, receiving this instruction, sends a gain control signal, which is the value to instruct the reflectance ratio of a previously determined reference white plate, to an amplifier 2. Thus, all the gradations are utilized effectively, and the high quality picture is obtained.
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