摘要 |
In order to detect a forgery of a document formed from an input image, additional information is added to the input image using general image processing without including a specific information adding section in a general image processing unit. M-value image data is input and converted to N-value image data, wherein the value M is larger than the value N, on the basis of threshold table groups composed of plural kinds of threshold tables whose using order is determined so as to indicate the predetermined additional information which is embedded in the image, and is used for detecting the forgery.
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