Parameterization for fading compensation

• US 7,277,486 B2
• Filed: 03/03/2003
• Issued: 10/02/2007
• Est. Priority Date: 05/03/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Srinivasan, Sridhar, Regunathan, Shankar
• Primary Examiner(s): DIEP, NHON THANH
• Application Number:
  US10/378,958
• Publication Number:
  US 20030206592A1
• Time in Patent Office: 1,674 Days
• Field of Search: 37524012-24016, 375/240.23, 348/222.1
• US Class Current: 375/240.12
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/517 by encoding
• CPC Class Codes: H04N 19/53 Multi-resolution motion estimation; Hierarchical motion estimation
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards
• CPC Class Codes: H04N 19/85 using pre-processing or post-processing specially adapted for video compression
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding
• CPC Class Codes: H04N 19/93 Run-length coding

Abstract

Techniques and tools for performing fading compensation in video processing applications are described. For example, during encoding, a video encoder performs fading compensation using fading parameters comprising a scaling parameter and a shifting parameter on one or more reference images. During decoding, a video decoder performs corresponding fading compensation on the one or more reference images.

Claims

1. A method of decoding one or more video images, the method comprising:

obtaining fading parameters comprising a scaling parameter and a shifting parameter;

performing fading compensation by computing plural remapped pixel values, wherein the plural remapped pixel values are based at least in part upon remapping of plural original pixel values used in a reference video image in terms of fading parameters, wherein the plural remapped pixel values include plural remapped chrominance values, and wherein the remapping for the plural remapped chrominance values uses the scaling parameter and a mean chrominance value;

performing motion compensation for at least part of a current video image using the plural remapped pixel values; and

outputting a reconstruction of the current video image.

2. The method of claim 1 wherein the scaling parameter is a contrast parameter and the shifting parameter is a brightness parameter.

3. The method of claim 2 wherein the fading parameters specify a pixel-wise linear transform comprising:

scaling luminance values of the plural original pixel values using the contrast parameter; and

shifting the scaled luminance values using the brightness parameter.

4. The method of claim 3 wherein the contrast parameter is greater than or equal to 0.5 and less than or equal to 1.5, and wherein the brightness parameter is greater than or equal to −

32 and less than or equal to 31.

5. The method of claim 2 wherein the fading parameters specify a linear transform comprising:

scaling luminance values of the plural original pixel values using the contrast parameter, wherein the contrast parameter is −

1; and

shifting the scaled luminance values using a modified brightness parameter.

6. The method of claim 1 wherein the scaling parameter is a contrast parameter.

7. The method of claim 6 wherein the fading parameters specify a pixel-wise linear transform comprising:

scaling chrominance values of the plural original pixel values using the contrast parameter.

8. The method of claim 1 wherein the fading compensation includes multiplying plural luminance values of the original pixel values by the scaling parameter and adding the shifting parameter to the result.

9. The method of claim 1 wherein the scaling parameter is a weighting parameter and the shifting parameter is an offset parameter.

10. The method of claim 1 wherein the fading parameters are fixed length coded.

11. The method of claim 1 wherein one or more of the fading parameters are variable length coded.

12. The method of claim 1 wherein the mean chrominance value is defined to be 128.

13. The method of claim 1 wherein the mean chrominance value is defined to be mean of possible chrominance values in an unsigned 8-bit representation.

14. A computer-readable medium storing computer-executable instructions for causing a computer system programmed thereby to perform the method of claim 1.

15. A computer-readable medium storing computer-executable instructions for causing a computer system programmed thereby to perform a method of processing a current video frame in a video sequence, the method comprising:

obtaining global luminance change compensation parameters for the current video frame;

performing global luminance change compensation by computing remapped pixel values, wherein the remapped pixel values are based at least in part upon remapping of original pixel values used in a reference video frame in terms of global luminance change compensation parameters, wherein the remapped pixel values include remapped chrominance values, and wherein the remapping for the remapped chrominance values uses a scaling parameter and a mean chrominance value;

performing motion compensation for at least part of the current video frame using the remapped pixel values; and

outputting a reconstruction of the current video frame.

16. The computer-readable medium of claim 15 wherein the scaling parameter is a contrast parameter.

17. The computer-readable medium of claim 16 wherein the global luminance change parameters specify a pixel-wise linear transform comprising:

scaling luminance values of the original pixel values using the contrast parameter; and

shifting the scaled luminance values using a brightness parameter.

18. The computer-readable medium of claim 16 wherein the global luminance change compensation parameters specify a pixel-wise linear transform comprising:

scaling chrominance values of the original pixel values using the contrast parameter.

19. The computer-readable medium of claim 15 wherein the method is performed during video decoding.

20. The computer-readable medium of claim 15 wherein the method is performed during video encoding.

21. The computer-readable medium of claim 15 wherein at least one of the global luminance change compensation parameters is variable length coded.

22. The computer-readable medium of claim 15 wherein the global luminance change compensation parameters are fixed length coded.

23. The computer-readable medium of claim 15 wherein the mean chrominance value is defined to be 128.

24. The computer-readable medium of claim 15 wherein the mean chrominance value is defined to be mean of possible chrominance values in an unsigned 8-bit representation.

25. A method of decoding video, the method comprising:

obtaining fading parameters for a portion of a current video frame;

performing fading compensation by computing plural remapped pixel values, wherein the plural remapped pixel values are based at least in part upon remapping of plural original pixel values used in a corresponding portion of a reference video frame in terms of fading parameters, wherein the plural remapped pixel values include plural remapped chrominance values, and wherein the remapping for the plural remapped chrominance values uses a scaling parameter and a mean chrominance value;

performing motion compensation for the portion of the current video frame using the plural remapped pixel values; and

outputting a reconstruction of the current video frame.

26. The method of claim 25 wherein the portion of the current video frame comprises one or more blocks.

27. The method of claim 25 wherein the portion of the current video frame comprises one or more macroblocks.

28. The method of claim 25 wherein the mean chrominance value is defined to be 128.

29. The method of claim 25 wherein the mean chrominance value is defined to be mean of possible chrominance values in an unsigned 8-bit representation.

30. A computer-readable medium storing computer-executable instructions for causing a computer system programmed thereby to perform the method of claim 25.

31. A method of encoding one or more video images, the method comprising:

obtaining fading parameters comprising a scaling parameter and a shifting parameter;

performing fading compensation by computing plural remapped pixel values, wherein the plural remapped pixel values are based at least in part upon remapping of plural original pixel values used in a reference video image in terms of fading parameters, wherein the plural remapped pixel values include plural remapped chrominance values, and wherein the remapping for the plural remapped chrominance values uses the scaling parameter and a mean chrominance value;

performing motion compensation for at least part of a current video image using the plural remapped pixel values; and

outputting at least the scaling parameter and the shifting parameter as part of an encoded video bitstream.

32. The method of claim 31 wherein the scaling parameter is a contrast parameter and the shifting parameter is a brightness parameter.

33. The method of claim 32 wherein the fading parameters specify a pixel-wise linear transform comprising:

scaling luminance values of the plural original pixel values using the contrast parameter; and

shifting the scaled luminance values using the brightness parameter.

34. The method of claim 33 wherein the contrast parameter is greater than or equal to 0.5 and less than or equal to 1.5, and wherein the brightness parameter is greater than or equal to −

32 and less than or equal to 31.

35. The method of claim 32 wherein the fading parameters specify a linear transform comprising:

scaling luminance values of the plural original pixel values using the contrast parameter, wherein the contrast parameter is −

1; and

shifting the scaled luminance values using a modified brightness parameter.

36. The method of claim 31 wherein the scaling parameter is a contrast parameter.

37. The method of claim 36 wherein the fading parameters specify a pixel-wise linear transform comprising:

scaling chrominance values of the plural original pixel values using the contrast parameter.

38. The method of claim 31 wherein the fading parameters are fixed length coded.

39. The method of claim 31 wherein one or more of the fading parameters are variable length coded.

40. The method of claim 31 wherein the mean chrominance value is defined to be 128.

41. The method of claim 31 wherein the mean chrominance value is defined to be mean of possible chrominance values in an unsigned 8-bit representation.

42. A computer-readable medium storing computer-executable instructions for causing a computer system programmed thereby to perform the method of claim 31.