US6252972B1
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US
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Method and arrangement for detecting a watermark using statistical characteristics of the information signal in which the watermark is embedded
Assignee: Civolution BV
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Filing: 1998-09-02
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Granted: 2001-06-26
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Expires: 2018-09-02
Abstract
Abstract Recently developed methods for copy protection rely on a watermark detector to judge whether multimedia content can be copied or not. In such copy protection schemes, a watermark detector examines the multimedia content and outputs a signal (D) indicating whether a watermark is present or not. Known watermark detectors determine a decision variable (y) indicating to which extent the watermark is present, for example, the amount of correlation between input signal and a reference copy of the watermark to be detected. The watermark is detected if the decision variable exceeds a predetermined threshold (y thr ) In accordance with the invention, the threshold value (y thr ) is adaptively controlled in dependence upon statistical characteristics of the information signal and a desired probability of false alarms (watermark detected whereas the signal is not watermarked). In an embodiment, the watermark detector determines the standard deviation (σ) of the pixel values threshold level and calculates the threshold value in accordance with the relation P ( falsealarm ) = erfc ( y thr σ ) in which erfc is the error function and σ is said standard deviation of the information signal values.
Inventors
- 👤 Johan P. M. G. Linnartz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:08
CPC Classifications
G; G06; G06T; G06T1/00; G06T1/0021; G06T1/005; G06T1/0078; H; H04; H04N; H04N1/00; H04N1/32; H04N1/32101; H04N1/32144; H04N1/32149; H04N5/00; H04N5/76; H04N5/91; H04N5/913; G06T2201/00; G06T2201/005; G06T2201/0065; H04N2005/91307; H04N2005/91335; H04N2201/00; H04N2201/32; H04N2201/3201; H04N2201/3225; H04N2201/3233; H04N2201/3269; H04N2201/327
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
72 words
An arrangement comprising: means for receiving a watermark embedded in an information signal; means for determining a decision variable indicating the extent to which the watermark is present in the signal; means for generating an output signal indicating detection of the watermark if the decision variable exceeds a predetermined threshold; and means for generating the threshold value depending on statistical characteristics of the information signal and a desired probability of erroneous detections.
Claim 2
Dependent Claim
72 words
An arrangement comprising: means for receiving a watermark embedded in an information signal; means for determining a decision variable indicating the extent to which the watermark is present in the signal; means for generating an output signal indicating detection of the watermark if the decision variable exceeds a predetermined threshold; and means for generating the threshold value depending on statistical characteristics of the information signal and a desired probability of erroneous detections.
Claim 3
Dependent Claim
34 words
The arrangement of claim 1 , wherein the threshold value generating means includes means for calculating the standard deviation or variance of information signal values to obtain the statistical characteristics of the information signal.
Claim 4
Dependent Claim
71 words
The arrangement of claim 2 , wherein the threshold value generating means further includes means for calculating the threshold value in accordance with the relation P ( falsealarm ) = erfc ( y thr σ ) in which P(falsealarm) is a desired probability of a false alarm, y the is the threshold value, erfc is the error function, and σ is the standard deviation of the information signal values.
Claim 5
Dependent Claim
96 words
The arrangement of claim 1 , wherein: the threshold value generating means includes means for calculating the standard deviation or variance of information signal values to obtain the statistical characteristics of the information signal; and the generating means includes means for calculating the threshold value in accordance with the relation P ( falsealarm ) = erfc ( y thr σ ) in which P(falsealarm) is a desired probability of a false alarm. y the is the threshold value, erfc is the error function, and σ is the standard deviation of the information signal values.
Claim 6
Independent Claim
67 words
A method comprising the steps of: providing a watermark embedded in an information signal; determining a decision variable indicating the extent to which the watermark is present in the signal; generating an output signal indicating detection of the watermark if the decision variable exceeds a predetermined threshold; and controlling the threshold value depending on statistical characteristics of the information signal and a desired probability of erroneous detections.
Claim 7
Independent Claim
67 words
A method comprising the steps of: providing a watermark embedded in an information signal; determining a decision variable indicating the extent to which the watermark is present in the signal; generating an output signal indicating detection of the watermark if the decision variable exceeds a predetermined threshold; and controlling the threshold value depending on statistical characteristics of the information signal and a desired probability of erroneous detections.
Claim 8
Dependent Claim
88 words
The method of claim 5 , wherein: the generating includes calculating the standard deviation or variance of information signal values to obtain the statistical characteristics of the information signal; and the generating includes calculating the threshold value in accordance with the relation P ( falsealarm ) = erfc ( y thr σ ) in which P(falsealarm) is a desired probability of a false alarm, y the is the threshold value, erfc is the error function and σ is the standard deviation of the information signal values.
Claim 9
Dependent Claim
75 words
Multimedia playing and/or recording apparatus, comprising: means for receiving a watermark embedded in an information signal; means for determining a decision variable indicating the extent to which the watermark is present in the signal; means for generating an output signal indicating detection of the watermark if the decision variable exceeds a predetermined threshold; and means for generating the threshold value depending on statistical characteristics of the information signal and a desired probability of erroneous detections.
Claim 10
Dependent Claim
75 words
Multimedia playing and/or recording apparatus, comprising: means for receiving a watermark embedded in an information signal; means for determining a decision variable indicating the extent to which the watermark is present in the signal; means for generating an output signal indicating detection of the watermark if the decision variable exceeds a predetermined threshold; and means for generating the threshold value depending on statistical characteristics of the information signal and a desired probability of erroneous detections.
Claim 11
Dependent Claim
98 words
The apparatus of claim 7 , wherein: the threshold value generating means includes means for calculating the standard deviation or variance of information signal values to obtain the statistical characteristics of the information signal; and the threshold value generating means includes means for calculating the threshold value in accordance with the relation P ( falsealarm ) = erfc ( y thr σ ) in which P(falsealarm) is a desired probability of a false alarm, y the is the threshold value, erfc is the error function, and σ is the standard deviation of the information signal values.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-06-25 | 2004-12-25 | 2005-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-06-25 | 2008-12-25 | 2009-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-06-25 | 2012-12-25 | 2013-06-26 | $7700.00 | Window Closed / Lapsed |