| 摘要 |
<p>For copyright protection, storage means stores a reference indicating an amount of information to determine whether a digital signal containing electronic watermark information is compressed. Extraction means extracts the amount of the electronic watermark information from the digital signal to be protected. Detector means collates the extracted amount with the reference amount to determine whether the signal has been compressed, and it permits the signal to be copied if uncompressed and prohibits it from being copied if compressed.</p> |
