DETECTING WATERMARK MODIFICATIONS

• US 20170148126A1
• Filed: 09/23/2016
• Published: 05/25/2017
• Est. Priority Date: 11/24/2015
• Status: Active Grant

• Current Assignee: The Nielsen Company LLC (MOOD Media Corporation)
• Original Assignee: The Nielsen Company LLC (MOOD Media Corporation)
• Inventors: Srinivasan, Venugopal
• Granted Patent: US 10,102,602 B2
• Time in Patent Office: Days
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 1/0071 using multiple or alternating watermarks
• CPC Class Codes: G06T 2201/0202 whereby the quality of watermarked images is measured; Measuring quality or performance of watermarking methods; Balancing between quality and robustness
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal

Abstract

Methods, apparatus, systems and articles of manufacture (e.g., physical storage media) to detect media watermark modifications are disclosed. Example watermark modification detection methods disclosed herein include encoding a second watermark in a media signal including a first watermark. Disclosed example methods also include detecting the first watermark and the second watermark in the media signal. Disclosed example methods further include, in response to detecting the first watermark and the second watermark, comparing a first strength metric determined for the first watermark and a second strength metric determined for the second watermark to determine whether the first watermark was modified prior to being encoded in the media signal.

Claims

1. A watermark modification detector comprising:

a watermark encoder to encode a second watermark in a media signal including a first watermark;

a watermark detector to detect the first watermark and the second watermark in the media signal; and

a watermark modification evaluator to compare a first strength metric determined for the first watermark and a second strength metric determined for the second watermark to determine whether the first watermark was modified prior to being encoded in the media signal.

2. The watermark modification detector of claim 1, wherein the first watermark is encoded in a first watermarking layer of the media signal, and the watermark encoder is to encode the second watermark in a second watermarking layer of the media signal.

3. The watermark modification detector of claim 2, wherein the second watermarking layer is an unused watermarking layer of the media signal.

4. The watermark modification detector of claim 1, wherein the watermark detector is further to:

sum energies of respective ones a first set of code tones of the media signal corresponding to symbols of the first watermark to determine the first strength metric; and

sum energies of respective ones of a second set of code tones of the media signal corresponding to symbols of the second watermark to determine the second strength metric.

5. The watermark modification detector of claim 4, wherein the respective energy of one of the first set of code tones is normalized based on a first average energy determined for a first code band of the media signal including the one of the first set of code tones, and the respective energy of one of the second set of code tones is normalized based on a second average energy determined for a second code band of the media signal including the one of the second set of code tones.

6. The watermark modification detector of claim 1, wherein the watermark modification evaluator is further to determine whether the second metric determined for the second watermark exceeds the first metric determined for the first watermark by at least a threshold value.

7. The watermark modification detector of claim 6, wherein the watermark modification evaluator is further to:

determine the first watermark was modified prior to being encoded in the media signal when the second metric exceeds the first metric by at least the threshold value;

determine the first watermark was not modified prior to being encoded in the media signal when the second metric does not exceed the first metric by at least the threshold value; and

report, via a network, information indicating whether the first watermark was modified prior to being encoded in the media signal.

8. A watermark modification detection method comprising:

encoding, by executing an with a processor, a second watermark in a media signal including a first watermark;

detecting, by executing an with the processor, the first watermark and the second watermark in the media signal; and

in response to detecting the first watermark and the second watermark, comparing, by executing an with the processor, a first strength metric determined for the first watermark and a second strength metric determined for the second watermark to determine whether the first watermark was modified prior to being encoded in the media signal.

9. The method of claim 8, wherein the first watermark is encoded in a first watermarking layer of the media signal, and the encoding of the second watermark includes encoding the second watermark in a second watermarking layer of the media signal.

10. The method of claim 9, wherein the second watermarking layer is an unused watermarking layer of the media signal.

11. The method of claim 8, further including:

summing energies of respective ones a first set of code tones of the media signal corresponding to symbols of the first watermark to determine the first strength metric; and

summing energies of respective ones of a second set of code tones of the media signal corresponding to symbols of the second watermark to determine the second strength metric.

12. The method of claim 11, wherein the respective energy of one of the first set of code tones is normalized based on a first average energy determined for a first code band of the media signal including the one of the first set of code tones, and the respective energy of one of the second set of code tones is normalized based on a second average energy determined for a second code band of the media signal including the one of the second set of code tones.

13. The method of claim 8, wherein the comparing of the first strength metric and the second strength metric includes determining whether the second metric determined for the second watermark exceeds the first metric determined for the first watermark by at least a threshold value.

14. The method of claim 13, further including:

determining the first watermark was modified prior to being encoded in the media signal when the second metric exceeds the first metric by at least the threshold value;

determining the first watermark was not modified prior to being encoded in the media signal when the second metric does not exceed the first metric by at least the threshold value; and

reporting, via a network, information indicating whether the first watermark was modified prior to being encoded in the media signal.

15. A tangible computer readable medium comprising computer readable instructions that, when executed, cause a processor to at least:

encode a second watermark in a media signal including a first watermark;

detect the first watermark and the second watermark in the media signal; and

in response to detecting the first watermark and the second watermark, compare a first strength metric determined for the first watermark and a second strength metric determined for the second watermark to determine whether the first watermark was modified prior to being encoded in the media signal.

16. The tangible computer readable medium of claim 15, wherein the first watermark is encoded in a first watermarking layer of the media signal, and to encode the second watermark, the instructions cause the processor to encode the second watermark in a second watermarking layer of the media signal.

17. The tangible computer readable medium of claim 16, wherein the second watermarking layer is an unused watermarking layer of the media signal.

18. The tangible computer readable medium of claim 15, wherein the instructions further cause the processor to:

sum energies of respective ones a first set of code tones of the media signal corresponding to symbols of the first watermark to determine the first strength metric; and

sum energies of respective ones of a second set of code tones of the media signal corresponding to symbols of the second watermark to determine the second strength metric.

19. The tangible computer readable medium of claim 18, wherein the respective energy of one of the first set of code tones is normalized based on a first average energy determined for a first code band of the media signal including the one of the first set of code tones, and the respective energy of one of the second set of code tones is normalized based on a second average energy determined for a second code band of the media signal including the one of the second set of code tones.

20. The tangible computer readable medium of claim 15, wherein the instructions further cause the processor to:

determine the first watermark was modified prior to being encoded in the media signal when the second metric exceeds the first metric by at least a threshold value;

determine the first watermark was not modified prior to being encoded in the media signal when the second metric does not exceed the first metric by at least the threshold value; and

report, via a network, information indicating whether the first watermark was modified prior to being encoded in the media signal.