Digital watermark detecting with weighting functions
First Claim
1. A method of detecting a digital watermark in a media signal comprising:
- computing a weighting function of a digitally watermarked signal;
applying the weighting function to the digitally watermarked signal to compute a weight-adjusted signal in which parts of the digitally watermarked signal that are more robust to distortion are weighted more than parts that are less robust to the distortion; and
recovering embedded auxiliary data symbols from the weight-adjusted signal.
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Abstract
A digital watermark detector uses weighting functions to enhance watermark detection. The weighting function applies more weight to parts of a digitally watermarked signal that are more robust to distortion. As such, the method provides for more reliable watermark detection, especially in applications where distortions, such as lossy compression or analog conversion, more accurate detection more difficult. In one version of the method, the detector projects the watermarked signal into a pseudorandom direction specified by a key, applies the weighting function, and extracts auxiliary data symbols from the projected signal by quantizing the projected signal and deriving the symbol values based on the quantization.
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Citations
20 Claims
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1. A method of detecting a digital watermark in a media signal comprising:
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computing a weighting function of a digitally watermarked signal;
applying the weighting function to the digitally watermarked signal to compute a weight-adjusted signal in which parts of the digitally watermarked signal that are more robust to distortion are weighted more than parts that are less robust to the distortion; and
recovering embedded auxiliary data symbols from the weight-adjusted signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of detecting a digital watermark in a media signal comprising:
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computing a weighting function of a digitally watermarked signal;
projecting the digitally watermarked signal into a direction according to a key;
applying the weighting function to the projected signal to compute a projected signal in which parts of the digitally watermarked signal that are more robust to distortion are weighted more than parts that are less robust to the distortion; and
recovering embedded auxiliary data symbols from the projected signal. - View Dependent Claims (16, 17, 18)
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19. A method of detecting a digital watermark in a media signal comprising:
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computing a weighting function of a digitally watermarked signal;
projecting the digitally watermarked signal into a direction according to a key;
applying the weighting function to the projected signal to compute a projected signal in which parts of the digitally watermarked signal that are more robust to distortion are weighted more than parts that are less robust to the distortion; and
recovering embedded auxiliary data symbols from the projected signal by quantizing the projected signal to determine a binary symbol associated with a quantization of the projected signal. - View Dependent Claims (20)
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Specification