METHOD AND APPARATUS FOR SPARSITY-BASED DE-ARTIFACT FILTERING FOR VIDEO ENCODING AND DECODING

• US 20110222597A1
• Filed: 11/18/2009
• Published: 09/15/2011
• Est. Priority Date: 11/25/2008
• Status: Active Grant

• Current Assignee: InterDigital Madison Patent Holdings (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Xu, Jun, Yin, Peng, Zheng, Yunfei, Sole, Joel
• Granted Patent: US 9,723,330 B2
• Time in Patent Office: Days
• US Class Current: 375/240.01
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/157 Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• 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 19/80 Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation H04N19/635, H04N19/86 take precedence
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

Methods and apparatus are provided for sparsity-based de-artifact filtering for video encoding and decoding. An apparatus includes an encoder (400) for encoding at least a portion of an image by grouping regions within the portion based on a grouping metric, transforming the grouped regions, adaptively performing de-artifact filtering on the transformed regions using a de-artifacting filter (413) included in the encoder, inverse transforming the de-artifacted regions to create replacement regions, and restoring the replacement regions to positions with the image from which the regions were taken prior to the grouping.

Claims

1. An apparatus, comprising:

an encoder (400, 600, 800) for encoding at least a portion of an image by grouping regions within the portion based on a grouping metric, transforming the grouped regions, adaptively performing de-artifact filtering on the transformed regions using a de-artifacting filter (465, 613, 813) comprised in the encoder, inverse transforming the de-artifacted regions to create replacement regions, and restoring the replacement regions to positions with the image from which the regions were taken prior to the grouping.

2. The apparatus of claim 1, wherein the de-artifacting filter (465, 613, 813) is configurable for use in any of an in-loop configuration and an out-of-loop configuration.

3. The apparatus of claim 2, wherein the de-artifacting filter (465, 613, 813) replaces a deblocking filter when said de-artifacting filter is applied the in-loop configuration.

4. The apparatus of claim 2, wherein the encoder (400, 600, 800) includes a deblocking filter, and said de-artifacting filter (465, 613, 813) is configured for use subsequent to the deblocking filter.

5. The apparatus of claim 1, wherein the de-artifacting filter (465, 613, 813) is a Wiener filter.

6. The apparatus of claim 1, wherein the replacement regions are combined using weights prior to restoring.

7. The apparatus of claim 6, wherein the grouped regions are transformed to obtain transform sparsity values there for, and the weights are determined responsive to the transform sparsity values.

8. The apparatus of claim 1, wherein at least one of a type and a strength of the de-artifact filtering is adaptively selected responsive to at least one of a quantization noise metric, a coding mode metric, a motion information metric, a local coding condition metric, and a compression requirements metric.

9. A method performed in a video encoder, comprising:

encoding at least a portion of an image,

wherein said encoding step comprises;

grouping (1020) regions within the portion based on a grouping metric;

transforming (1025A) the grouped regions;

adaptively performing de-artifact filtering (1025B) on the transformed regions using a de-artifacting filter;

inverse transforming (1025C) the de-artifacted regions to create replacement regions; and

restoring the replacement regions to positions with the image from which the regions were taken prior to the grouping.

10. The method of claim 9, further comprising configuring the de-artifacting filter for use in any of an in-loop configuration and an out-of-loop configuration.

11. The method of claim 10, further comprising replacing a deblocking filter with the de-artifacting filter when the de-artifacting filter is applied the in-loop configuration.

12. The method of claim 10, wherein the encoder includes a deblocking filter, and the method further comprises configuring the de-artifacting filter for use subsequent to the deblocking filter.

13. The method of claim 9, further comprising combining the replacement regions using weights prior to said restoring step.

14. The method of claim 13, wherein the grouped regions are transformed to obtain transform sparsity values there for, and the weights are determined responsive to the transform sparsity values.

15. The method of claim 9, wherein said adaptively performing step comprises adaptively selecting at least one of a type and a strength of the de-artifact filtering responsive to at least one of a quantization noise metric, a coding mode metric, a motion information metric, a local coding condition metric, and a compression requirements metric.

16. The method of claim 9, further comprising applying a secondary filter before or after the de-artifacting filter.

17. An apparatus, comprising:

a decoder (500, 700, 900) for decoding at least a portion of an image by grouping regions within the portion based on a grouping metric, transforming the grouped regions, adaptively performing de-artifact filtering on the transformed regions using a de-artifacting filter (565, 713, 913) comprised in the decoder, inverse transforming the de-artifacted regions to create replacement regions, and restoring the replacement regions to positions with the image from which the regions were taken prior to the grouping.

18. The apparatus of claim 17, wherein the de-artifacting filter (565, 713, 913) is configurable for use in any of an in-loop configuration and an out-of-loop configuration.

19. The apparatus of claim 18, wherein the de-artifacting filter (565, 713, 913) replaces a deblocking filter when said de-artifacting filter is applied the in-loop configuration.

20. The apparatus of claim 18, wherein the decoder (500, 700, 900) includes a deblocking filter, and said de-artifacting filter (565, 713, 913) is configured for use subsequent to the deblocking filter.

21. The apparatus of claim 17, wherein the de-artifacting filter (565, 713, 913) is a Wiener filter.

22. The apparatus of claim 17, wherein the replacement regions are combined using weights prior to restoring.

23. The apparatus of claim 22, wherein the grouped regions are transformed to obtain transform sparsity values there for, and the weights are determined responsive to the transform sparsity values.

24. The apparatus of claim 17, wherein at least one of a type and a strength of the de-artifact filtering is adaptively selected responsive to at least one of a quantization noise metric, a coding mode metric, a motion information metric, a local coding condition metric, and a compression requirements metric.

25. A method performed in a video decoder, comprising:

decoding at least a portion of an image,

wherein said decoding step comprises;

grouping (1120) regions within the portion based on a grouping metric;

transforming (1125A) the grouped regions;

adaptively performing de-artifact filtering (1125B) on the transformed regions using a de-artifacting filter;

inverse transforming (1125C) the de-artifacted regions to create replacement regions; and

restoring the replacement regions to positions with the image from which the regions were taken prior to the grouping.

26. The method of claim 25, further comprising configuring the de-artifacting filter for use in any of an in-loop configuration and an out-of-loop configuration.

27. The method of claim 26, further comprising replacing a deblocking filter with the de-artifacting filter when the de-artifacting filter is applied the in-loop configuration.

28. The method of claim 26, wherein the decoder includes a deblocking filter, and the method further comprises configuring the de-artifacting filter for use subsequent to the deblocking filter.

29. The method of claim 25, wherein the de-artifacting filter is a Wiener filter.

30. The method of claim 25, further comprising combining the replacement regions using weights prior to said restoring step.

31. The method of claim 30, wherein the grouped regions are transformed to obtain transform sparsity values there for, and the weights are determined responsive to the transform sparsity values.

32. The method of claim 25, wherein said adaptively performing step comprises adaptively selecting at least one of a type and a strength of the de-artifact filtering responsive to at least one of a quantization noise metric, a coding mode metric, a motion information metric, a local coding condition metric, and a compression requirements metric.

33. A storage media having video signal data encoded thereupon, comprising:

at least a portion of an image encoded by grouping regions within the portion based on a grouping metric, transforming the grouped regions, adaptively performing de-artifact filtering on the transformed regions using a de-artifacting filter comprised in the encoder, inverse transforming the de-artifacted regions to create replacement regions, and restoring the replacement regions to positions with the image from which the regions were taken prior to the grouping.