| 摘要 |
PURPOSE:To perform always an optimum gamma compensation in accordance with the density level of an original image, by setting perliminarily plural density correction functions for every maximum density level of the original. CONSTITUTION:An image signal read by a CCD 1 is applied to an A/D converter 3 through an amplifier 2 and is converted to a digital signal and is applied to an ROM 6. Meanwhile, the output of the amplifier 2 has the peak value detected and held in a peak holding circuit 4, and the peak value is applied to a comparing circuit 5 and is compared with a reference value to detect a maximum density level of the output of the CCD. Gamma compensation values for input density levels are stored preliminarily in the ROM 6 in accordance with plural density compensation functions, and a density correction function is selected on a basis of the maximum density level detected by the comparing circuit 5, and thus, gamma compensation is performed in accordance with the output of the A/D converter 3. |
