Optimal denoising for video coding

• US 8,369,417 B2
• Filed: 05/18/2007
• Issued: 02/05/2013
• Est. Priority Date: 05/19/2006
• Status: Active Grant

• Current Assignee: Hong Kong University of Science and Technology
• Original Assignee: Hong Kong University of Science and Technology
• Inventors: Au, Oscar Chi Lim, Guo, Liwei
• Primary Examiner(s): Orgad, Edan
• Assistant Examiner(s): JACKSON, JENISE E
• Application Number:
  US11/750,498
• Publication Number:
  US 20070291842A1
• Time in Patent Office: 2,090 Days
• Field of Search: 375/240.27, 375/240, 375/240.12, 375/240.16, 375/240.24, 375/240.22
• US Class Current: 375/240.27
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

An optimal denoising method for video coding. This method makes use of very few pixels and linear operations, and can be embedded into the motion compensation process of video encoders. This method is simple and flexible, yet offers high performance and produces appealing pictures.

Claims

1. A method implemented by a video encoder of denoising in video coding, comprising:

dividing a current frame into blocks;

selecting at least one other video frame;

selecting a current block from said current frame and a reference block corresponding to the current block from said at least one other video frame;

generating a residue block as a function of a difference between said current block and said reference block; and

performing a linear combination based at least in part on a mean compensation, wherein a weight of the mean compensation is determined adaptively and at least partially dependent on a variance and a mean of the residue block, and the linear combination is performed on pixels contained in said current block and corresponding pixels contained in said reference block to output denoised values.

2. The method of claim 1, wherein said pixels are sets of sub-pixels at sub-pixel locations.

3. The method of claim 1, wherein said at least one other video frame is not sequentially adjacent to said current frame.

4. The method of claim 1, further comprising:

obtaining said reference block including performing a search within a predefined search area related to said current block as a function of a difference between said current block and said reference block.

5. The method of claim 4, wherein said performing said search includes implementing a full search algorithm.

6. The method of claim 1, wherein said blocks are each a 3×

3 square used to perform motion estimation and obtain the reference block.

7. The method of claim 1, wherein said blocks are rectangular.

8. The method of claim 1, wherein said blocks are each a hexagon.

9. The method of claim 1, wherein said blocks each contain one pixel.

10. The method of claim 1, wherein the mean compensation is constructed as a function of said variance and said mean of said residue block.

11. The method of claim 1, wherein said video frames are denoised frames and non-denoised frames.

12. The method of claim 1, wherein said video frames are past frames and future frames.

13. The method of claim 1, wherein said video frames are never-encoded frames and previously-encoded frames.

14. A method implemented by a video encoder of denoising in video coding, comprising:

selecting a current frame and at least one other reference frame;

obtaining a predicted frame by performing motion estimation on said at least one other reference frame;

dividing said current frame and said predicted frame into current blocks in said current frame and co-located blocks in said predicted frame;

performing motion compensation to obtain a residue frame comprising residue blocks constructed as a function of a difference between said current blocks and said co-located blocks;

generating denoised values by performing linear combination, with weight determined adaptively and at least partially dependent on a variance and a mean of said residue blocks, in dependence of said predicted frame and said residue frame.

15. The method of claim 14, wherein said performing said motion estimation is adaptive to estimated noise variance of said co-located blocks.

16. The method of claim 15, wherein said performing said motion estimation includes a linear combination of said co-located blocks with the weight determined adaptively in dependence of the estimated noise variance of said co-located blocks.

17. The method of claim 14, wherein said generating said denoised values by performing said linear combination is integrated with said performing said motion compensation.

18. A video coding system, comprising:

a filter; and

a video coding unit;

wherein said filter operates in conjunction with said video coding unit to perform;

selection of a current frame and at least one other reference frame;

construction of a predicted frame by performance of motion estimation on said at least one other reference frame;

determination of current blocks and co-located blocks by division of said current frame and said at least one other reference frame;

construction of a residue frame containing residue blocks obtained by performance of motion compensation as a function of a difference between said current blocks and said co-located blocks; and

determination of new values by performance of a linear combination on said predicted frame and said residue frame with weights determined adaptively and at least partially dependent on a variance and a mean of said residue blocks; and

wherein said video coding unit operates on said new values to generate a denoised frame.

19. The system of claim 18, wherein said filter operates in conjunction with said video coding unit to integrate said determination of said new values with said determination of said residue frame.