| 摘要 |
PURPOSE:To suppress a noise without spoiling a half tone, by setting two threshold levels by the information around a remarkable picture element, and adding the maximum and minimum density on the scanning line to the intermediate density. CONSTITUTION:An input image signal provided to the terminal 1 is digitally converted by the A/D converter 2, is stored in the buffer memory 3, also is added by the adder 4, and a density level of the maximum frequency is stored in the memory 5. The maximum density A, the minimum density B, the standard deviation value of a density level and two threshold levels are derived by the comparator 6 and the arithmetic unit 7. One and the other of the threshold levels are made the standard value for deciding a white level and a black level, respectively, and as for the half tone, its output signal is obtained by adding each density of the maximum and the minimum, therefore, a noise can be suppressed without spoiling the half tone. |
