| 摘要 |
The main CPU executes Fourier transform to the partial image, then performs strict spectrum analysis 1 for judging the presence/absence of data at a coordinate position designated in advance on a Fourier transform plane with high resolution for judging the presence/absence of prohibition of duplication, then judges whether duplication-prohibited data exists or not, and clears both the partial image and the document image if it is judged that duplication-prohibited data exists. If it is judged that duplication-prohibited data does not exist, the main CPU executes spectrum analysis 2 for broadly inspecting the existence of a periodic component instead of lowering the resolution from the spectrum analysis 1 and judges whether a structure other than DC component exists or not. If the existence of a minute quantity of change that could not exist in a normal image is recognized, the main CPU performs partial image processing such as amplifying the quantity of change, then superimposes it onto the document image, and supplies the image on which the superimposing processing has been executed, to an output unit and a liquid crystal display unit, thus outputting or displaying the image.
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