| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming device that can properly select and set a threshold level (hereinafter abbreviated 'THL') to be a reference for discriminating an original area from an out-original area so as to realize a more accurate out-original delete function. SOLUTION: The image forming device of this invention can manually or automatically set the THL. In this case, a proper THL can be set by selecting the most proper THL among several THLs prepared in advance through the manual setting or by utilizing histogram data shown in Figure through the automatic setting. In the case of utilizing the histogram data especially, calculating an arithmetic mean between a luminance value at a peak P1 expressing the out-original area and that at a peak P2 of an original background can set a proper THL or utilizing a skirt or the like of the histogram data can obtain the THL. |
