R. Mitsuhashi, K. Morooka, and H. Nagahashi (Japan)
B´ezier Surface, Subdivision, Watermark Embedding
This paper proposes a new method for embedding dig ital watermarks into B´ezier polynomial patches. A sur face is supposed to be represented by multiple piece wise B´ezier polynomial patches. A B´ezier patch passes through its four-corner control points, which are called data points, and does not pass through the other control points. To embed a watermark, a B´ezier patch is divided into two patches by PPM(Piecewise Parametric Modeling) method[1][2] which we already proposed. Since each sub divided patch shares two data points of the original patch, the subdivision apparently generates two additional data points on the boundaries of the original patch. We can gen erate new data points in any position on the boundaries by changing the division parameters in PPM. The additional data points can not be removed without knowing the pa rameters, and hence the division enables us to embed some information as a watermark into the patch. Different divi sions give different watermarks.
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