| 摘要 |
PROBLEM TO BE SOLVED: To form an image with high fidelity in winch the resolution of characters can be made high, and the graininess of a photograph can be made smooth. SOLUTION: An image feature extracting part 130 detects the edge quantity of image data 100, and quantizes it to an edge level A having 9 levels ranging from a level 9 (the maximum edge level) to a level 8 (non-edge) after extending the area. As for the edge quantity quantizing method, a linear quantizing method or a non-linear quantizing method with a level 8 until the edge quantity of a certain value can be switched according to a signal 102. A quantization threshold oscillating with oscillation width corresponding to an edge level A is generated by a quantization threshold generating part 140, and picture data are quantized by a picture data quantization processing part 120 by an error diffusing method by using the quantization threshold.
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