Media signal filtering for use in digital watermark reading
First Claim
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1. A filtering method for reading a digital watermark comprising:
- applying a filter to an array of samples of a media signal, wherein the filter compares a sample of interest with each of a plurality of neighboring samples, for each comparison generates a result based on the comparison, sums the result, and replaces the sample of interest with the sum; and
decoding a digital watermark from the filtered media signal.
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Abstract
A curve fitting method is used to synchronize a reader of embedded data in a media signal. A circular reference signal is embedded in the media signal. After geometric distortion of the media signal, the reference signal is distorted, yet still detectable. The amount of distortion is derived by detecting the reference signal, and applying a curve fitting method from which the distortion is calculated.
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Citations
19 Claims
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1. A filtering method for reading a digital watermark comprising:
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applying a filter to an array of samples of a media signal, wherein the filter compares a sample of interest with each of a plurality of neighboring samples, for each comparison generates a result based on the comparison, sums the result, and replaces the sample of interest with the sum; and decoding a digital watermark from the filtered media signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A filtering method for reading a digital watermark comprising:
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applying a filter to an array of samples of a media signal, wherein the filter computes functions of a sample of interest and a plurality of neighboring samples to generate a plurality of results corresponding to the functions applied to the sample of interest and the neighboring samples, combines the results into an output value, and replaces the sample of interest with the output value; and decoding a digital watermark from the filtered media signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A pre-filter for processing a media signal before decoding a digital watermark comprising:
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an operator for computing a function of a sample of interest and each of selected neighboring samples of the media signal to generate a plurality of results; and a summer for summing the results into an output value;
the output value replacing the sample of interest;
wherein the digital watermark is decoded from output values computed by applying the filter to the media signal.
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Specification