EMBEDDING MULTIPLE WATERMARKS

摘要

In order to enable a data signal, such as an audio or video signal, to be marked with multiple watermarks a set of different codes or keys is used within a given application field. The set of codes/keys is known to a watermark embedder (20) and a watermark detector (22). In each watermark embedding step, whether it is a first embedding step or a subsequent embedding step, a different key is used. The embedder (22) includes a data extractor (24) for determining which key or keys has or have been used previously. A data generator (26) then selects a new key from the set of known keys.