New patents are issued by the USPTO on Tuesdays. Both of this week's Spotlight Patents concern aspects of digital watermarking. Assigned to Xerox, the first patent addresses techniques for 3D printer steganography. Assigned to Nielsen, the second patent addresses techniques for down-mixing compensation for audio watermarking.
9,706,076, "3D printer steganography," assigned to Xerox
When printing 3D objects a print file to be executed by a 3D printer to generate a 3D object is analyzed to identify candidate regions for insertion of printer ID information that identifies the printer printing the 3D object. Code describing the printer identification information is inserted into the print file at appropriate locations to cause the 3D printer to print one or more structures representing the printer identification information in one or more identified candidate regions. The printer identification information is printed by omitting or replacing one or more voxels in the printed object. Structures representing the printer identification information may include, e.g., barcodes, glyphs, alphanumeric sequences, etc. The printer identification information may include, e.g., a printer serial number and/or time stamp, manufacturer copyright and/or trademark information, etc.
9,704,494, "Down-mixing compensation for audio watermarking," assigned to Nielsen.
Example methods, apparatus, systems and articles of manufacture to implement down-mixing compensation for audio watermarking are disclosed. Example watermark embedding methods disclosed herein include determining a first attenuation factor associated with a first audio channel of a multi-channel audio signal based on first down-mixed audio samples obtained from down-mixing the first audio channel and a second audio channel of the multi-channel audio signal, determining a second attenuation factor associated with a third audio channel of the multi-channel audio signal based on second down-mixed audio samples obtained from down-mixing the second audio channel and the third audio channel of the multi-channel audio signal, selecting one of the first attenuation factor or the second attenuation factor to be a third attenuation factor associated with the second audio channel of the multi-channel audio signal, and embedding a watermark in the second audio channel based on the third attenuation factor.