| 摘要 |
PURPOSE:To obtain a copy image which is controlled to have a correct density value, by obtaining a frequency distribution function of the detection frequency for density from the original to be copied and by performing the smoothing processing to detect one density value. CONSTITUTION:Original 11b to be copied is irradiated by reference light source 12, and the reflection light is converted to a reflection signal by photo diode 14 and is amplified by 15 and is supplied to processing circuit part 3. The analogue signal obtained by this reflection signal shows the frequency distribution for density, and this signal is converted to a digital signal by AD converter A/D and is stored in the register of central processing unit CPU through interface circuit I/O at a fixed sampling period. CPU stores the frequency distribution, which is the detection frequency of density values, in the RAM and performs the smoothing processing untill the number of maximum values of the frequency distribution becomes two or less, and further, one density value is detected by the density value detecting means, and the picture quality of the copy image is controlled by this density value. |
