| 摘要 |
This invention relates to a watermarking scheme that is robust to general distortions such as scaling and rotation of multimedia content (audio, video, images). This is achieved by embedding a watermark in a first component of the host signal and a transformed version of the same watermark in a second component. For example, a watermark is embedded in the luminance component (Y) and a cyclically shifted version thereof in the chrominance component (UV) of a video signal. The detector correlates ( 46 ) the luminance watermark with all cyclicly shifted versions of the chrominance watermark. The highest correlation peak indicates the shift that was applied at the embedder end. By comparing the shift thus found with the original value, the scaling and rotation factors are retrieved ( 47 ). The invention allows the scaling and rotation operations to be undone, after which the embedded watermark can reliably be detected in a conventional manner.
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