New patents are issued by the USPTO on Tuesdays. This week's Spotlight Patents concern aspects of digital watermarking and digital fingerprinting. Assigned to GoPro, the first patent addresses techniques for an inter frame watermark in a digital video. Assigned to Sorenson Media, the second patent addresses techniques for detecting channel change in automatic content recognition fingerprint matching.
9,877,036, "Inter frame watermark in a digital video," assigned to GoPro, Inc.
Watermark data is converted to watermark coefficients, which may be embedded in an image by converting the image to a frequency domain, embedding the watermark in image coefficients corresponding to medium-frequency components, and converting the modified coefficients to the spatial domain. The watermark data is extracted from the modified image by converting the modified image to a frequency domain, extracting the watermark coefficients from the image coefficients, and determining the watermark data from the watermark coefficients. The watermark data may be truncated image data bits such as truncated least significant data bits. After extraction from the watermark, the truncated image data bits may be combined with data bits representing the original image to increase the bit depth of the image. Watermark data may include audio data portions corresponding to a video frame, reference frames temporally proximate to a video frame, high-frequency content, sensor calibration information, or other image data.
9,877,085, 'Detecting channel change in automatic content recognition fingerprint matching," assigned to Sorenson Media, Inc.
A method includes receiving broadcast fingerprints indicative of broadcast frames of broadcast media streams being streamed to a plurality of channels by a broadcaster and receiving television (TV) fingerprints indicative of an ordered sequence of TV frames of a TV media stream at a corresponding media device. The method further includes matching the TV fingerprints with the broadcast fingerprints by determining a difference between respective broadcast fingerprints and corresponding TV fingerprints of the ordered sequence of TV frames. The matching includes populating a binary tree structure with respective differences. The method also includes detecting a channel change of the media device from a first channel to a second channel in response to locating a value indicative of the channel change in the binary tree structure within a threshold number of children nodes from a root node upon traversing down the binary tree structure.