| 摘要 |
PROBLEM TO BE SOLVED: To accurately judge that even a dot area of low density is a dot area. SOLUTION: An image processor includes an expansion processing unit 115 which performs expansion processing on a binary image as an object of area judgement, a change point number calculation unit 112 which calculates the number of change points of pixels arrayed in a main scanning direction in a judgement object area of the binary image having been subjected to the expansion processing by the expansion processing unit 115, the number of change points of pixels arrayed in a sub-scanning direction, the number of change points of pixels arrayed in a first oblique direction having a predetermined angle to the main scanning direction, and the number of change points of pixels arrayed in a second oblique direction nearly orthogonal to the first oblique direction respectively, and a dot area judgement unit 114 which judges that the judgement object area is a dot area when all of the four numbers of change points calculated by the change point number calculation unit 112 are larger than respective predetermined thresholds. COPYRIGHT: (C)2009,JPO&INPIT
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