Method and apparatus for superposing a digital watermark and method and apparatus for detecting a digital watermark

An apparatus for superposing a digital watermark for superposing digital watermark information on an information data signal bearing original information, the apparatus comprising:

• an auxiliary embedding circuit that embeds position information in the information data signal to produce a changed information data signal;
• and
• a main embedding circuit that embeds the digital watermark information in the changed information data signal,
• wherein the position information bears information for recognizing a position of the digital watermark information.

A method comprising:

• embedding position information in an information data signal to produce a changed information data signal;
• embedding a digital watermark information in the changed information data signal;
• detecting the position information from the changed information data signal;
• and
• detecting the digital watermark information from the changed information data digital based on the detected position information,
• wherein the position information bears information for recognizing a position of the digital watermark information embedded.

A system comprising:

• an auxiliary embedding circuit that embeds position information in an information data signal to produce a changed information data signal;
• a main embedding circuit that embeds a digital watermark information in the changed information data signal;
• a position information detector that detects the position information from the changed information data signal;
• and
• a watermark information detector that detects the digital watermark information from the changed information data signal based on the detected position information,
• wherein the position information bears information for recognizing a position of the digital watermark information.