Watermark placement in watermarking of time varying media signals
First Claim
Patent Images
1. A method of placing a watermark in a video stream comprising:
- estimating motion between frames in the video stream;
computing a representative motion for at least part of a frame to be embedded with a digital watermark; and
spatially adjusting the digital watermark by the representative motion;
wherein the representative motion is derived from motion of blocks in a frame, and the motion of the blocks used to derive the representative motion is weighted based on the watermark energy to be carried in the blocks such that blocks carrying more watermark signal are weighted more heavily; and
wherein said representative motion comprises a dominant motion derived from motion statistics for the frame and spatially adjusting the digital watermark by the dominant motion.
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Abstract
A method of placing a watermark in a video stream estimates motion between frames in the video stream, and computes a representative motion for a frame. Before embedding the watermark in that frame, the method spatially adjusts a digital watermark by the representative motion. This method is particularly suited for embedding a watermark in a video stream compressed using motion estimation. In this case, the method uses the motion vectors in the video stream to compute a dominant motion for a frame, and then shifts the watermark by this dominant motion before embedding it in the frame.
139 Citations
15 Claims
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1. A method of placing a watermark in a video stream comprising:
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estimating motion between frames in the video stream; computing a representative motion for at least part of a frame to be embedded with a digital watermark; and spatially adjusting the digital watermark by the representative motion;
wherein the representative motion is derived from motion of blocks in a frame, and the motion of the blocks used to derive the representative motion is weighted based on the watermark energy to be carried in the blocks such that blocks carrying more watermark signal are weighted more heavily; and
wherein said representative motion comprises a dominant motion derived from motion statistics for the frame and spatially adjusting the digital watermark by the dominant motion. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of placing a watermark in a compressed data stream comprised of frames of time varying data, where the data stream includes frames compressed using motion estimation, the method comprising:
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computing a representative motion for a frame based on motion data in the compressed data stream; and spatially adjusting a digital watermark to be embedded in the frame by the representative motion of the frame;
wherein the representative motion is derived from motion of blocks in a frame, and the motion of the blocks used to derive the representative motion is weighted based on the watermark energy to be carried in the blocks such that blocks carrying more watermark signal are weighted more heavily; and
wherein said representative motion comprises a dominant motion derived from motion statistics for the frame and spatially adjusting the digital watermark by the dominant motion. - View Dependent Claims (9, 10, 11, 12)
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13. A method of placing a watermark in a compressed video data stream comprised of frames of time varying data, where the data stream includes frames compressed using motion estimation, the method comprising:
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extracting motion vectors for a frame in the compressed video data stream; computing a representative motion for at least one part of the frame based on the motion vectors in the compressed data stream; and spatially adjusting a digital watermark by the representative motion before embedding the adjusted watermark in the part of the frame;
wherein the motion vectors are weighted according to an amount of watermark energy to be embedded in blocks of the video frame corresponding to the motion vectors; and
wherein said representative motion comprises a dominant motion derived from motion statistics for the frame and spatially adjusting the digital watermark by the dominant motion. - View Dependent Claims (14, 15)
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Specification