1
Ravi K Sharma, Adnan M Alattar, Farid Ahmed, Geoffrey B Rhoads: Wavelet domain watermarks. Digimarc Corporation, Joel R Meyer, Digimarc Corporation, May 7, 2002: US06385329 (298 worldwide citation)

A wavelet domain watermark encoder and decoder embed and detect auxiliary signals in a media signal, such as a still image, video or audio signal. A watermark orientation signal is embedded in a wavelet decomposed signal to facilitate detection of the watermark in a geometrically distorted version o ...


2
Geoffrey B Rhoads, Ravi K Sharma: Watermark detection using a fourier mellin transform. Digimarc Corporation, Joel R Meyer, Digimarc Corporation, June 18, 2002: US06408082 (245 worldwide citation)

A watermark detector maps target media data into a log polar coordinate system and correlates the target media with a detection watermark to compute orientation parameters. The correlation process computes a measure of correlation for an array of potential orientation parameter candidates. Evaluatin ...


3
Brett T Hannigan, Ravi K Sharma, Stephen K Decker, Phillip Andrew Seder, Tony F Rodriguez, Andrew Klonsky: Digital watermarking methods and related toy and game applications. Digimarc Corporation, March 10, 2009: US07502759 (185 worldwide citation)

The present invention relates to toys and game applications that are enhanced with digital watermarks. In one embodiment, a character card includes a unique identifier in the form of a digital watermark. The identifier is used to link to a database record, which can be updated to reflect changes in ...


4
Geoffrey B Rhoads, Ravi K Sharma: Determining transformations of media signals with embedded code signals. Digimarc Corporation, Joel R Meyer, Digimarc Corporation, July 23, 2002: US06424725 (166 worldwide citation)

An embedded signal detection process determines a transformation of a media signal subsequent to the encoding of an embedded code signal into the media signal. The process performs a logarithmic sampling of the media signal to create a sampled signal in which scaling of the media signal is converted ...


5
Geoffrey B Rhoads, Ravi K Sharma: Digital watermark screening and detection strategies. Digimarc Corporation, Digimarc Corporation, July 27, 2004: US06768809 (128 worldwide citation)

To enhance decoding of signals suspected of containing an embedded auxiliary signal, a suspect signal is screened to compute detection values evincing presence and strength of the embedded signal. Screening strategies control detector actions, such as rejecting un-marked signals, improving synchroni ...


6
Geoffrey B Rhoads, Ravi K Sharma: Extracting digital watermarks using logarithmic sampling and symmetrical attributes. Digimarc Corporation, Joel R Meyer, Digimarc Corporation, March 9, 2004: US06704869 (118 worldwide citation)

A digital watermark reader performs a logarithmic sampling of a watermarked media signal to produce a sampled signal. It then analyzes the sampled signal to detect attributes associated with a watermark signal. It extracts a digital watermark based on detected attributes associated with the watermar ...


7
Geoffrey B Rhoads, Ravi K Sharma: Digital watermark screening and detecting strategies. Digimarc Corporation, Joel R Meyer, Digimarc Corporation, February 4, 2003: US06516079 (111 worldwide citation)

To enhance decoding of signals suspected of containing a watermark, a suspect signal is screened to compute detection values evincing presence and strength of a watermark. Screening strategies control detector actions, such as rejecting un-marked signals and improving synchronization of watermarks i ...


8
Ravi K Sharma, Adnan M Alattar, Farid Ahmed, Geoffrey B Rhoads: Wavelet domain watermarks. Digimarc Corporation, January 15, 2008: US07319775 (106 worldwide citation)

A wavelet domain watermark encoder and decoder embed and detect auxiliary signals in a media signal, such as a still image, video or audio signal. A watermark orientation signal is embedded in a wavelet decomposed signal to facilitate detection of the watermark in a geometrically distorted version o ...


9
Geoffrey Rhoads, Adnam M Alattar, Ravi K Sharma: Pre-filteriing to increase watermark signal-to-noise ratio. Digimarc Corporation, Digimarc Corporation, January 17, 2006: US06988202 (99 worldwide citation)

Utilizes pre-processing (pre-filtering) of target data in order to facilitate and enable robust extraction of a watermark signal. With the present invention the watermarked data is pre-filtered using knowledge of the watermark signal. That is, utilizing knowledge of the characteristics of the waterm ...


10
Ravi K Sharma: Watermark orientation signals conveying payload data. Digimarc Corporation, February 2, 2010: US07657058 (96 worldwide citation)

Steganographic calibration signals (sometimes termed “orientation signals,” “marker signals,” reference signals,” “grid signals,” etc.) are sometimes included with digital watermarking signals so that subsequent distortion of the object thereby marked (e.g., a digital image file, audio clip, documen ...