VIDEO DEBLOCKING FILTER

• US 20110069765A1
• Filed: 05/26/2010
• Published: 03/24/2011
• Est. Priority Date: 09/20/2004
• Status: Active Grant

• Current Assignee: Sonic IP Incorporated (Endeavor Group Holdings Inc.)
• Original Assignee: DIVX Incorporated (FIG LLC (d/b/a Fortress Investment Group LLC))
• Inventors: Huang, Cheng
• Granted Patent: US 8,139,651 B2
• Time in Patent Office: Days
• US Class Current: 375/240.29
• CPC Class Codes: H04B 1/66 for reducing bandwidth of signals; for improving efficiency of transmission H04B1/68 takes precedence
• 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 19/176 the region being a block, e.g. a macroblock
• 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

Deblocking filters are disclosed, where the nature of the filter is determined based upon the level of detail of a reconstructed video frame in the region in which the block boundary is located. One embodiment of the method of the invention includes identifying a boundary between two blocks of the reconstructed video frame, determining the level of detail of the reconstructed video frame in a region in which the block boundary is located, wherein the region includes pixels from multiple rows and multiple columns of the reconstructed video frame and includes at least one pixel that is not immediately adjacent the block boundary and selecting a filter to apply to predetermined pixels on either side of the block boundary based upon the determined level of detail.

Claims

1. A method of deblocking a reconstructed video frame, comprising:

identifying a boundary between two blocks of the reconstructed video frame;

determining the level of detail of the reconstructed video frame in a region in which the block boundary is located, wherein the region includes pixels from multiple rows and multiple columns of the reconstructed video frame and includes at least one pixel that is not immediately adjacent the block boundary;

selecting a filter to apply to predetermined pixels on either side of the block boundary based upon the determined level of detail.

2. The method of claim 1, wherein the determination of the level of detail of the reconstructed video frame in a region in which the block boundary is located further comprises taking the sum of the absolute difference of at least some of the pixels within a set of pixels surrounding the block boundary.

3. The method of claim 2, wherein:

the block boundary is a horizontal block boundary;

the set of pixels is a block of pixels that is divided by the horizontal block boundary;

the sum of the absolute difference is taken for each vertically adjacent pair of pixels in each column of the block of pixels, except the pair of pixels that are separated by the block boundary.

4. The method of claim 2, wherein the set of pixels is an 8×

8 block that is evenly divided by the horizontal block boundary.

5. The method of claim 4, wherein the determination of the level of detail involves calculating the following sum:

6. The method of claim 4, wherein the determination of the level of detail involves calculating the following sum:

7. The method of claim 3, wherein the set of pixels is a 4×

8 block that is evenly divided by the horizontal block boundary.

8. The method of claim 7, wherein the determination of the level of detail involves calculating the following sum:

9. The method of claim 7, wherein the determination of the level of detail involves calculating the following sum:

10. The method of claim 2, wherein:

the block boundary is a vertical block boundary;

the set of pixels is a block of pixels that is divided by the vertical block boundary;

the sum of the absolute difference is taken for each adjacent pair of pixels in each row of the block of pixels, except the pair of pixels that are separated by the block boundary.

11. The method of claim 10, wherein the set of pixels is an 8×

8 block that is evenly divided by the vertical block boundary.

12. The method of claim 11, wherein the determination of the level of detail involves calculating the following sum:

13. The method of claim 11, wherein the determination of the level of detail involves calculating the following sum:

14. The method of claim 10, wherein the set of pixels is an 8×

4 block that is evenly divided by the vertical block boundary.

15. The method of claim 14, wherein the determination of the level of detail involves calculating the following sum:

16. The method of claim 14, wherein the determination of the level of detail involves calculating the following sum:

17. The method of claim 1, wherein selecting a filter to apply to predetermined pixels on either side of the block boundary based upon the determination of the level of detail comprises comparing the determined level of detail to a threshold.

18. The method of claim 17, wherein the threshold varies depending upon the quantizer used in the encoding of the blocks at the block boundary.

19. The method of claim 17, wherein selecting a filter to apply to predetermined pixels on either side of the block boundary based upon the determination of the level of detail further comprises:

when the level of detail exceeds the threshold, selecting a filter to apply to predetermined pixels;

wherein selection of a filter comprises determining the detail of the image in the region of the pixels being filtered.

20. The method of claim 19, wherein:

the block boundary is a horizontal block boundary; and

determining the detail of the image in the region of the pixels being filtered comprises calculating the following expression with respect to a column of pixels divided by the horizontal block boundary;

(|v<sub>−

2</sub>-v<sub>−

1</sub>|*3+|v<sub>−

1</sub>-v₁|*2+|v₁-v₂|*3)//8

where;

v_i is the chrominance of the pixel i pixels from the horizontal block boundary.