Every Tuesday the US Patent and Trademark Office issues new patents. This weeks selection address various aspects of watermarking. Assigned to Toshiba, the first patent address techniques for watermark detection. Assigned to Sony, the second patent addresses the use of two watermarks.
7,284,130, "Digital watermark detection method and apparatus," assigned to Kabushiki Kaisha Toshiba (JP).
A specific frequency component extraction unit extracts a specific frequency component signal from an input image signal. A phase controller controls the phase of the specific frequency component signal. A correlator computes the cross-correlation value of the phase-controlled specific frequency component signal and the input image signal. A watermark information estimation unit filters the cross-correlation value to detect watermark information embedded in the input image signal.
7,284,128, "Recording medium, recording medium method and apparatus, information signal output control method, recording medium reproducing apparatus, signal transmission method, and content data," assigned to Sony (JP).
A record medium for recording an information signal in which a first watermark and a second watermark have been embedded, the first watermark being embedded when the information signal is transmitted as an analog signal, the second watermark being embedded when the information signal is further transmitted.