Computing distortion of media signals using embedded data with repetitive structure and log-polar mapping
First Claim
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1. A method of determining distortion of a signal with embedded data comprising:
- transforming the signal into a transform domain to produce peaks due to a repetitive structure of the embedded data in the signal;
performing a mapping of the transformed signal to convert distortion of the embedded data into a shift; and
performing a correlation of the mapped signal with a signal representing an expected pattern of peaks associated with the repetitive structure of the embedded data signal, wherein the correlation detects the shift, and the shift provides a measure of the distortion of the signal.
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Abstract
A digital watermark detection method uses a matched filtering technique on a log polar re-mapping of a watermarked signal to detect peaks associated with a repetitive structure of a watermark.
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Citations
20 Claims
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1. A method of determining distortion of a signal with embedded data comprising:
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transforming the signal into a transform domain to produce peaks due to a repetitive structure of the embedded data in the signal;
performing a mapping of the transformed signal to convert distortion of the embedded data into a shift; and
performing a correlation of the mapped signal with a signal representing an expected pattern of peaks associated with the repetitive structure of the embedded data signal, wherein the correlation detects the shift, and the shift provides a measure of the distortion of the signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of detecting a digital watermark in a signal comprising:
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transforming the signal into a transform domain to emphasize a repetitive structure of the digital watermark in the signal;
performing a mapping of the transformed signal to convert geometric distortion of the digital watermark into a shift; and
performing a detection of the digital watermark in the mapped signal using an expected pattern corresponding to data embedded in the digital watermark. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of detecting a digital watermark in an image signal comprising:
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computing the autocorrelation of the image signal to emphasize a repetitive structure of the digital watermark in the signal;
performing a log polar mapping of the transformed signal to convert rotation and spatial scaling of the digital watermark into shifts; and
performing a detection of the digital watermark in the log polar mapped signal using a pattern corresponding to data embedded in the digital watermark. - View Dependent Claims (17, 18, 19, 20)
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Specification