On Tuesdays the USPTO issues new patents. Both of today's Spotlight Patents concern aspects of digital watermarking, which continues to be a "hot topic" relative to DRM patents. Assigned to Microsoft, the first patent addresses techniques for audio watermarking with covert channel and permutations. Assigned to Digimarc, the second patent addresses techniques for content processing using reversable watermarking.
7,543,148, "Audio watermarking with covert channel and permutations," assigned to Microsoft.
Audio signals, such as a music clip, are inserted with detectable watermarks. The inserted watermark can identify the content producer and provide a signature embedded in the audio signal and cannot be removed. The watermark can survive all typical kinds of processing and malicious attacks. The watermark can be implemented in a watermarking system that employs a covert channel encoder to layer an additional information data message or covert message on top of the watermark. The watermarking system can also include a permutation technique to further hide the watermark and hide the covert message within the watermark.
7,542,587, " Content processing methods using reversible watermarking," assigned to Digimarc.
The ability to remove a watermark from an encoded image opens the possibility of various novel applications. Several such applications are detailed. One employs a reversible watermark in conjunction with a second (robust) watermark. In this arrangement, the payload of the reversible watermark conveys information about the robust watermark (e.g., encoding parameters, or an error signal), permitting removal of the robust watermark from an uncorrupted encoded image. By such arrangements, the encoded image can be fully restored to its pristine, unencoded state even if several different watermarks have been applied.