A digital watermarking apparatus that embeds two watermarks in host data is provided. The first watermarking block generates a plurality of watermarking location candidates of the first watermark, and embeds the first watermark into the respective location candidates of the host data, and then selects...http://www.google.co.uk/patents/US20040101160?utm_source=gb-gplus-sharePatent US20040101160 - Multilayered digital watermarking system
