| 摘要 |
PURPOSE:To process an input image under optimum processing conditions by judging whether the input image is a half tone image or a line drawing based on a high frequency component of the input image. CONSTITUTION:With a video signal of an original, a high frequency component is separated by a high-pass filter HP. The high frequency component is added to a gate circuit G1 through a waveform shaping circuit WF, and only a signal contained in an original-content judging area is taken out by a timing signal inputted through a terminal IT 4 and inputted to a frequency-voltage converter fvc 1. The output of the converter is applied to a differential amplifier D, and it is judged whether the content of the original is a high spatial frequency original containing many fine charactors and lines or a low spatial frequency original frequently containing halftones such as illustrations or photographs. The output of the differential amplifier D becomes a control signal that controls the adherence of developing agents to a photosensitive drum through a sample hold SH, a control circuit DC. |
