Full color visibility model using CSF which varies spatially with local luminance

Patent metadata

Field	Value
Publication number	US-9565335-B2
Application number	US-201615137401-A
Country	US
Kind code	B2
Filing date	Apr 25, 2016
Priority date	Jan 2, 2014
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

The present disclosure relate generally to image signal processing, color science and signal encoding. One claim recites an apparatus including: an input for obtaining color image data; memory for storing a luminance contrast sensitivity function (CSF 1 ) and a chrominance contrast sensitivity function (CSF 2 ); means for degrading data representing color image data with the CSF 1 and the CSF 2 to predict visibility changes attributable to encoding plural-bit information in the obtained color image data, in which the CSF 1 varies depending on luminance values associated with local regions of the color image data, in which said means for degrading data representing color image data yields results for different image areas within the color image data, and in which the CSF 1 is used for degrading luminance data and the CSF 2 is used for degrading chrominance data; and means for altering the color image data by encoding plural-bit information therein, in which signal embedding strength of the encoding within the different image areas varies based on the results. Of course, other features, combinations and claims are disclosed as well.

First claim

What is claimed is:

1. An apparatus comprising:
memory for storing: i) a luminance contrast sensitivity function (CSF 1 ), ii) a chrominance contrast sensitivity function (CSF 2 ), and iii) data representing color imagery; and
one or more processors configured for:
applying the CSF 1 and the CSF 2 to predict degradation of image areas associated with an application of digital watermarking to the data representing color imagery, in which the CSF 1 varies depending on luminance values associated with local regions of the data representing color imagery and in which the CSF 1 is used for processing luminance data and the CSF 2 is used for processing chrominance data;
transforming the data representing color imagery with digital watermarking, in which the digital watermarking is guided based on results obtained from the applying including predicted degradation of image areas.

2. The apparatus of claim 1 in which the CSF 1 varies spatially.

3. The apparatus of claim 1 in which the CSF 1 varies spatially in terms of spatial width.

4. The apparatus of claim 2 in which the CSF 2 varies spatially in terms of spatial width.

5. The apparatus of claim 1 in which the applying the CSF 1 to predict degradation of image areas produces image blurring as the predicted degradation, in which the CSF 1 varies so that relatively more blurring occurs as luminance of a local image region decreases.

6. The apparatus of claim 1 in which the digital watermarking is guided based on results obtained from the applying by varying embedding strength across different image areas of the data representing color imagery based on predicted degradation of the different image areas.

7. The apparatus of claim 6 in which predicted degradation of the digital watermarking across the different image areas comprises uniform predicted degradation.

8. The apparatus of claim 1 in which said one or more processors are configured for processing the data representing color imagery with an attention model to predict visual traffic areas.

9. The apparatus of claim 8 in which the digital watermarking is guided based on the results obtained from the predicted visual traffic areas and the predicted degradation of image areas.

10. The apparatus of claim 1 in which the chrominance contrast sensitivity function (CSF 2 ) comprises a blue-yellow contrast sensitivity function and a red-green contrast sensitivity function.

11. The apparatus of claim 1 in which the CSF 2 varies depending on luminance values associated with local regions of the obtained color image data.

12. The apparatus of claim 1 in which the transforming the data representing color imagery with digital watermarking embeds a machine-readable code into the data representing color imagery.

13. The apparatus of claim 1 in which the color imagery comprises video.

14. An apparatus comprising:
an input for obtaining color image data;
memory for storing a luminance contrast sensitivity function (CSF 1 ) and a chrominance contrast sensitivity function (CSF 2 );
means for degrading data representing color image data with the CSF 1 and the CSF 2 to predict visibility changes attributable to encoding plural-bit information in the obtained color image data, in which the CSF 1 and the CSF 2 each varies depending on luminance values associated with local regions of the color image data, in which said means for degrading data representing color image data yields results for different image areas within the color image data, and in which the CSF 1 is used for degrading luminance data and the CSF 2 is used for degrading chrominance data; and
means for altering the color image data by encoding plural-bit information therein, in which signal strength of the encoding within the different image areas varies based on the results.

15. The apparatus of claim 14 in which said means for degrading data representing color image data with the CSF 1 introduces image blurring, and in which the CSF 1 varies so that relatively more blurring occurs as luminance of a local image region decreases.

16. The apparatus of claim 14 in which said means for altering the color image data varies the signal strength of the encoding across different image regions of the color image data to yield uniform predicted visibility of the encoding across the data representing the color image data.

17. The apparatus of claim 14 in which the CSF 1 varies spatially in terms of spatial width.

18. The apparatus of claim 14 in which the CSF 2 varies spatially in terms of spatial width.

19. The apparatus of claim 14 in which the chrominance contrast sensitivity function (CSF 2 ) comprises a blue-yellow contrast sensitivity function and a red-green contrast sensitivity function.

20. The apparatus of claim 14 in which said means for altering the color image data comprises a digital watermark embedder.

21. The apparatus of claim 14 in which the color image data represents video data.

22. A method comprising:
obtaining color image data;
obtaining a luminance contrast sensitivity function (CSF 1 ) and a chrominance contrast sensitivity function (CSF 2 );
using one or more configured processors, applying the CSF 1 and the CSF 2 to the obtained color image data to predict visibility changes attributable to encoding plural-bit information in the obtained color image data, in which the CSF 1 and the CSF 2 each varies based on luminance values associated with local regions of the color image data, in which said applying yields results associated with predicted visibility changes attributable to different image areas within the obtained color image data, and in which the CSF 1 is applied to luminance data associated with the obtained color image data and the CSF 2 is applied to chrominance data associated with the obtained color image data; and
using one or more configured processors, encoding plural-bit information within the obtained color image data, in which signal strength of the encoding varies across the different image areas based on the results.

23. The method of claim 22 in which said applying introduces image blurring to the obtained color image data, and in which the CSF 1 varies so that relatively more blurring occurs as luminance of a local image region decreases.

24. The method of claim 22 in which the signal strength of the encoding varies across different image regions of the color image data to yield uniform predicted visibility of the encoding across the data representing the color image data.

25. The method of claim 22 in which the CSF 1 varies spatially in terms of spatial width.

26. The method of claim 22 in which the CSF 2 varies spatially in terms of spatial width.

27. The method of claim 22 in which the chrominance contrast sensitivity function (CSF 2 ) comprises a blue-yellow contrast sensitivity function and a red-green contrast sensitivity function.

28. The method of claim 22 in which the obtained color image data represents video data.

29. The method of claim 22 in which the encoding comprises digital watermarking.

30. A method comprising:
obtaining data representing color imagery;
using one or more programmed processors, filtering the data representing color imagery with a luminance contrast sensitivity function (CSF 1 ) and a chrominance contrast sensitivity function (CSF 2 ) to yield resul

Assignees

• Digimarc Corp

Inventors

• Reed Alastair M
• Falkenstern Kristyn R
• Berfanger David
• Bai Yang

Classifications

• H04N1/32309 Primary

  in colour image data · CPC title

• G06T2201/0202

  whereby the quality of watermarked images is measured; Measuring quality or performance of watermarking methods; Balancing between quality and robustness · CPC title

• G06T1/0028 Primary

  Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking · CPC title

• H04N1/6005

  with luminance or chrominance signals, e.g. LC1C2, HSL or YUV · CPC title

• H04N2201/3233

  of authentication information, e.g. digital signature, watermark · CPC title