| 摘要 |
PURPOSE:To attain accurate correction while increasing the resolution or a conversion circuit by using a peak of a read value based on one-line reading as a reference value of the conversion circuit converting the peak value into a binarization data or a multileveling data. CONSTITUTION:A peak value holding circuit 30 holding the peak of a reading value based on one-line reading is provided and the peak value holding circuit is connected to the conversion circuit 20 using the output of the peak value holding circuit as a reference value. Thus, the data of a reference light level is brought into a level close to a predetermined reference value and the resolution of the conversion circuit is increased to apply accurate correction. Moreover, the peak value of the preceding line is used as the reference value to facilitate the correspondence of the copying to the change even if the background color of the original is changed.
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