On Tueadays the USPTO issues new patents. Both of today's Spotlight Patents concern aspects of digital watermarking. Assigned to Verance, the first patent addresses technques for efficient and secure forensic marking in compressed domains. Assigned to Thomson (FR), the second patent addresses techniques for correlating two data sections.
8,259,938, "Efficient and secure forensic marking in compressed [domains]," assigned to Verance.
Methods, devices, and computer program products enable the embedding of forensic marks in a host content that is in compressed domain. These and other features are achieved by preprocessing of a host content to provide a plurality of host content versions with different embedded watermarks that are subsequently compressed. A host content may then be efficiently marked with forensic marks in response to a request for such content. The marking process is conducted in compressed domain, thus reducing the computational burden of decompressing and re-compressing the content, and avoiding further perceptual degradation of the host content. In addition, methods, devices and computer program products are disclosed that obstruct differential analysis of such forensically marked content.
8,259,873, "Method and apparatus for correlating two data sections," assigned to Thomson (FR).
Watermarking of audio signals intends to manipulate the audio signal in a way that the changes in the audio content cannot be recognized by the human auditory system. The watermark data are decoded from the received watermarked audio signal by correlation with corresponding candidate reference sequences. One or more of the sync symbols are embedded twice in the watermark data frame in the encoder. Thereafter a circular correlation is calculated instead of a standard correlation.