| US 7,451,320 B2 | ||
| Digital watermark detection method and apparatus | ||
| Wataru Asano, Yokohama (Japan); Shinichiro Koto, Machida (Japan); and Tomoo Yamakage, Yokohama (Japan) | ||
| Assigned to Kabushiki Kaisha Toshiba, Tokyo (Japan) | ||
| Filed on May 25, 2007, as Appl. No. 11/753,988. | ||
| Application 11/753988 is a division of application No. 10/626610, filed on Jul. 25, 2003, granted, now 7,284,130. | ||
| Claims priority of application No. 2002-218404 (JP), filed on Jul. 26, 2002. | ||
| Prior Publication US 2007/0230740 A1, Oct. 04, 2007 | ||
| Int. Cl. G06K 9/46 (2006.01) | ||
| U.S. Cl. 713—176 [382/190; 382/191] | 6 Claims |
| 1. A digital watermark detection apparatus which detects watermark information embedded in an input image signal, comprising:
a correlator configured to compute an auto-correlation function of the input image signal;
a generator configured to generate a specific frequency component signal by filtering the auto-correlation function using
a high pass filter having a specific cutoff frequency or a band pass filter having a passband center frequency; and
a detector unit configured to detect the watermark information from the specific frequency component signal by determining
a polarity of a peak of the specific frequency component signal.
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