| 摘要 |
PROBLEM TO BE SOLVED: To impart a forgery preventive function and a machine-reading function to a continuous gradation image. SOLUTION: As a halftone region to print halftone dots, two kinds of halftone regions, an m×m pixel (m>=2, m is an integer) and an n×n pixel (1<=n<m, n is an integer), are provided. Then, four halftone regions of the m×m pixels, which are in regions being independent from each other, surround the periphery of one halftone region of the n×n pixel without a gap, and the four halftone regions of the n×n pixels which are in regions being independent from each other are arranged with equal intervals along the outer periphery of the one halftone region of the m×m pixel for the constitution. Then, halftone dots which are obtained by image-processing a specified input image, and of which the duplication is difficult by a present photochemical processor, and at the same time, which can be machine-read are printed using both of the halftone regions of the two kinds of halftone regions.
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