| 摘要 |
PURPOSE:To exactly discriminate a character, a photograph, and a dotted area by comparing the variation amount of the maximum value and the minimum value of the difference between the densities of a higher density signal with an original image variable density signal in which character areas and halftone areas are mixed. CONSTITUTION:A higher band emphasis processing circuit 11 executes the filtering processing for higher band emphasis, and generates a higher band variable density signal from the variable density data of an original image variable density signal. This higher band emphasizing signal and an original variable density signal are scanned with the window of a prescribed size in an area decision circuit 12, and the maximum value and the minimum value of the density of both signals are obtained, then, the difference between respective maximum values and that between the minimum values are respectively compared with a prescribed threshold. After thus discriminating the area, its result is inputted to a selection circuit 30; a most suitablly processed binary image is selected from among the three kinds of outputs from an image forming device 20, and transmitted to an output device. Since the variation amount of the maximum value and the minimum value varies among a character, a picture, and a dot, these different areas can be exactly discriminated from each other.
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