| 摘要 |
PROBLEM TO BE SOLVED: To provide an image processing method and image processing device capable of embedding an electronic watermark into a two-valued image like a document (e.g., a black and white two-valued image), embedding an electronic watermark into an image which is recoded by a recording method using error diffusion treatment, and reliably retrieving sub-information from the electronic-watermark-embedded image. SOLUTION: Block error diffusion treatment is performed to main image information, and one of two kinds of special pixels (achromatic pixel) is selected according to the result. One of two kinds of key information is selected according to 0/1 of the sub-information, color difference modulation treatment is performed to the selected key information, and superimposition processing is performed using the result and the selected particular pixels, thus composite image information being created, in which sub-information is embedded into the main image information in an invisible state. When the sub-information is recovered from the composite image information afterwards, it is recovered by extracting the frequency distribution of the key information from the composite image information. COPYRIGHT: (C)2009,JPO&INPIT
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