Importance

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Abstract

The present invention relates to methods for watermark-embedding/extracting identification information into/from picture data and apparatuses thereof. When identification information is watermark-embedded, the following steps are performed. Combinations of basis functions orthogonal each other are generated in association with each numerical signal. For each combination of the orthogonal basis functions, a weight coefficient is calculated so as to correspond to the combination of the basis functions by calculating a sum of products of values of the basis functions for pixels in the original picture data and pixel values of the pixels. For each numerical signal, a watermark-embedding function is referred, a input value is specified, and a pixel value is changed. When the identification information is extracted from the picture data, for each weight coefficient, the watermark-embedding function is referred, and the value of the watermark-embedding function is calculated for each weight coefficient.

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First Claim