ELECTRONIC WATERMARK GENERATION APPARATUS, ELECTRONIC WATERMARK GENERATION METHOD, ELECTRONIC WATERMARK GENERATION PROGRAM, ELECTRONIC WATERMARK DETECTING APPARATUS, AND ELECTRONIC WATERMARK DETECTING PROGRAM

摘要

PROBLEM TO BE SOLVED: To increase an amount of information which can be provided with an electronic watermark.

SOLUTION: A multivalued signal is distributed in a frequency space to generate a signal pattern, and it is subjected to inverse discrete Fourier transform to generate a watermark pattern in an image space. The multivalued signal is generated by gathering binary signals which can be robustly detected as a cluster and generating signals different in characteristics such as shape and area. Thereby, robust multivalued signals can be attained. After these multivalued signals are used for the watermark pattern, an original signal pattern is restored when it is transformed to the frequency space through discrete Fourier transform, and each restored signal however can be identified each other. According to this embodiment, a characteristic amount of original signal can be recognized and a signal different in a value can be distinguished.

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