| 摘要 |
PURPOSE:To execute proper density adjustment simply by calculating a difference between a density level of a background part of an original for read data by one line and a corresponding reference density level, adjusting a reference voltage for A/D conversion to eliminate the difference and executing the operation in parallel with reading. CONSTITUTION:When an automatic exposure adjustment mode is set, image data is written in a line RAM 50 via a shading circuit 46 based on a shift pulse SH. A CPU 42, based on the data, extracts the density data corresponding to the background level and the black level, controls a reference voltage signal Dref based on the data to adjust the reference voltage of an A/D converter 44. Thus, the data for density adjustment is read in the unit of lines and the reference voltage of A/D conversion is controlled based on the data and since the density adjustment is executed in parallel with image reading, neither preparatory scanning nor special sensor for density detection is required.
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