| 摘要 |
PROBLEM TO BE SOLVED: To attain improvement in identification accuracy by discriminating whether a second concerned pixel is a pixel belonging to a dot area, while using a feature amount calculated from the dot feature amount calculating means. SOLUTION: A maximal/minimal pixel detecting part 61 outputs an identification signal of whether the density value of a concerned pixel (a) is a maximal point or minimal point in a first local block from an image signal stored in a block memory (a). A maximal/minimal pixel feature amount calculating part 62 calculates the information of density gradient from the concerned pixel (a) to a pixel in main scanning, sub-scanning or oblique direction in the image signal stored in the block memory (a). A maximal/minimal pixel classifying part 63 outputs a classifying signal to the concerned pixel (a) corresponding to the said identification signal and output information. While using the classifying signal stored in a block memory (b), a dot feature amount calculating part 64 calculates the feature amount of a concerned pixel (b) from a feature parameter expressing the characteristics of a dot area. A dot discriminating part 65 outputs the identification signal as to whether the concerned pixel (b) is the pixel in the dot area.
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