| 摘要 |
PURPOSE:To prevent production in a change in a copy picture density even when the AE mode is selected by generating a reference level based on both of reference density information obtained through the read of a reference density pattern and background density information of a picture read from an original. CONSTITUTION:In the case of reading a picture, a reference density board is read at first by an image sensor 1. Then a level of Vin is A/D-converted and the result is Do(x). The Do(x) by one line is stored in an address of a RAM 12 in response to the scanning timing as the reference data. Only a part of the picture data outputted from an A/D converter 7 is extracted and given to an averaging circuit. A peak hold circuit detects a maximum value Dmax (background level) while a WIND signal of a mean value Dtyp inputted sequentially is at H and holds and outputs it. When the AE mode is set, the DrefAE is adjusted in response to the background level of the data D(x) and the result is fed to a D/A converter 10, in which the value Vref is revised. |
