Method, system and device for improving video quality through in-loop temporal pre-filtering

• US 9,025,676 B2
• Filed: 07/10/2012
• Issued: 05/05/2015
• Est. Priority Date: 09/19/2005
• Status: Active Grant

• Current Assignee: Geo Semiconductor Incorporated
• Original Assignee: Geo Semiconductor Incorporated
• Inventors: Chen, Lulin, Tourapis, Alexandros Michael, Alvarez, Jos Roberto
• Primary Examiner(s): Carter, Aaron W
• Application Number:
  US13/545,930
• Publication Number:
  US 20130003872A1
• Time in Patent Office: 1,029 Days
• Field of Search: 382260-265, 375/E7.135, 375/E7.162, 375/E7.163, 375/E7.181, 375/E7.19, 375/E7.211, 375/240.29
• US Class Current: 375/240.29
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• 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 19/137 Motion inside a coding unit, e.g. average field, frame or block difference
• 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 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/615 using motion compensated temporal filtering [MCTF]
• 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

A method, system and device are provided for pre-filtering device for filtering a video signal prior to digitally encoding. The method includes receiving at least one input picture and at least one reconstructed picture from an encoding process and performing an in-loop temporal filtering process using at least one input picture and at least one reconstructed picture from an encoding process to output a pre-filtered video signal for use in an encoding process. The result is enabling an encoding process to produce an output with increased temporal correlation between adjacent pictures regardless of the coding type, since the artifacts introduced by the encoding process are also considered by the process.

Claims

1. A method for a pre-filtering device to filter a video signal prior to digitally encoding, comprising:

receiving at least one input picture;

receiving at least one reconstructed picture from an encoding process;

receiving a plurality of motion vectors from a motion estimator; and

performing an in-loop temporal filtering process by combining the at least one input picture and the at least one reconstructed picture to output a pre-filtered video signal for use in an encoding process, wherein at least one of picture statistics and the plurality of motion vectors are applied in the in-loop temporal filtering process; and

wherein the combining step includes;

performing a picture type selection process to generate selected picture data;

performing a picture characterization process to produce characterized data; and

generating parameters based on the characterized data.

2. The method according to claim 1, wherein the in-loop temporal filtering process includes generating the picture statistics.

3. The method according to claim 1, further comprising receiving picture statistics from an external source, wherein the in-loop temporal filtering process includes separately generating the picture statistics.

4. The method according to claim 1, further comprising receiving picture statistics from a video pre-process.

5. The method according to claim 1, further comprising receiving the picture statistics from a video pre-filtering process.

6. The method according to claim 1, further comprising receiving the picture statistics from an encoding process.

7. The method according to claim 1, further comprising combining the parameters generated, the selected picture data and the reconstructed picture data to produce in-loop filtered data.

8. The method according to claim 1, wherein the step of performing an in-loop temporal filter process further includes combining the input picture and the reconstructed picture from the encoding process to output a pre-filtered video signal for use in an encoding process, and this step of combining further includes:

performing stationary and weight computations of an input picture and a reconstructed picture to produce stationary and weight values for coefficients of a formula to generate a pre-filtered input value to an encoder that compensates for artifacts introduced by the encoding process.

9. The method according to claim 8, further comprising:

means for determining whether the stationary value is substantially zero, generating a filtered value for the input picture according to a formula based on the set stationary and weight values if the motion of the input video picture is low compared to the reconstructed picture.

10. The method according to claim 8, further comprising:

determining whether the stationary value is substantially zero, outputting the original input if the motion of the input video picture is high compared to the reconstructed picture.

31. The method of claim 1, wherein the encoding process includes at least an entropy based encoding.

11. A system for a pre-filtering device to filter a video signal prior to digitally encoding, comprising:

means for receiving at least one input picture;

means for receiving at least one reconstructed picture from an encoding process;

means for receiving a plurality of motion vectors from a motion estimator; and

means for performing an in-loop temporal filtering process by combining the at least one input picture and the at least one reconstructed picture to output a pre-filtered video signal for use in an encoding process wherein at least one of picture statistics and the plurality of motion vectors are applied in the in-loop temporal filtering process; and

wherein the combining step includes;

performing a picture type selection process to generate selected picture data;

performing a picture characterization process to produce characterized data; and

generating parameters based on the characterized data.

12. The system according to claim 11, wherein the means for performing in-loop temporal filtering process includes means generating the picture statistics.

13. The system according to claim 11, further comprising means for receiving the picture statistics from an external source, wherein the means for performing an in-loop temporal filtering process includes means for separately generating the picture statistics.

14. The system according to claim 11, further comprising means for receiving the picture statistics from a video pre-process.

15. The system according to claim 11, further comprising means for receiving the picture statistics from a video pre-filtering process.

16. The system according to claim 11, further comprising means for receiving the picture statistics from an encoding process.

17. The system according to claim 11, further comprising means for combining the parameters generated, the selected picture data and the reconstructed picture data to produce in-loop filtered data.

18. The system according to claim 11, wherein the means for performing an in-loop temporal filter process further includes means for combining the input picture and the reconstructed picture from the encoding process to output a pre-filtered video signal for use in an encoding process, and this means for combining further includes:

means for performing stationary and weight computations of an input picture and a reconstructed picture to produce stationary and weight values for coefficients of a formula to generate a pre-filtered input value to an encoder that compensates for artifacts introduced by the encoding process.

19. The system according to claim 18, further comprising:

means for determining whether the stationary value is substantially zero, means generating a filter value for the input picture according to a formula based on the set stationary and weight values if the motion of the input video picture is low compared to the reconstructed picture.

20. The system according to claim 18, further comprising:

means for determining whether the stationary value is substantially zero, means for outputting the original input if the motion of the input video picture is high compared to the reconstructed picture.

21. A pre-filtering device for filtering a video signal prior to digitally encoding the video signal, comprising:

an in-loop temporal filter having a first input for receiving at least one input picture;

having a second input for receiving at least one reconstructed picture from an encoding process; and

having a third input for receiving a plurality of motion vectors from a motion estimator;

wherein the in loop temporal filter is configured to output a pre-filtered video signal for use in an encoding process by combining the at least one input picture and the at least one reconstructed picture, wherein at least one of picture statistics and the plurality of motion vectors are applied in the in-loop temporal filtering process; and

wherein the combining step includes;

performing a picture type selection process to generate selected picture data;

performing a picture characterization process to produce characterized data; and

generating parameters based on the characterized data.

22. The pre-filtering device according to claim 21, further comprising statistics storage, a second temporal filter configured to temporally filter a video picture and output and store temporal statistics data to the statistics storage, and a spatial filter configured to output spatial statistic data to the statistics storage, wherein the in-loop temporal filter is configured to receive statistics data from statistics storage.

23. The pre-filtering device according to claim 22, wherein the in-loop temporal filter is configured to generate statistical data and also to receive statistical data to replace statistical data related to the spatial filtered data from the spatial filter and the temporally filtered data from the second temporal filter.

24. The pre-filtering device according to claim 22, wherein the in-loop temporal filter is configured to generate statistical data and also to receive statistical data to complement statistical data related to the spatial filtered data from the spatial filter and the temporally filtered data from the second temporal filter.

25. The pre-filtering device according to claim 21, further comprising an internal statistics generator configured to generate the picture statistics for use in an in-loop temporal filtering process.

26. The pre-filtering device according to claim 25, wherein stationary and weight values are determined based on a motion value.

27. The pre-filtering device according to claim 25, wherein the internal statistics generator is configured to determine stationary values based on preprocessing data related to motion.

28. The pre-filtering device according to claim 25, wherein the internal statistics generator is further configured with a programmable look-up table to derive stationary values from statistics generated in the in-loop pre-filtering device.

29. The pre-filtering device according to claim 27, wherein the look-up table has stationary values for use in performing an in-loop temporal filtering process.

30. The pre-filtering device according to claim 22, wherein the in-loop temporal filter is configured to generate statistical data internally with a look-up table and also to receive statistical data in addition to statistical data related to the spatial filtered data from the spatial filter and the temporally filtered data from the second temporal filter.