Method and apparatus for controlling loop filtering or post filtering in block based motion compensationed video coding

• US 6,931,063 B2
• Filed: 03/26/2001
• Issued: 08/16/2005
• Est. Priority Date: 03/26/2001
• Status: Expired due to Term

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Sun, Shijun, Lei, Shawmin
• Primary Examiner(s): An, Shawn S.
• Application Number:
  US09/817,701
• Publication Number:
  US 20020136303A1
• Time in Patent Office: 1,604 Days
• Field of Search: 375/240.16, 375/240.12, 375/240.25, 375/240.26, 375/240.29, 375/240.24, 375/240.18, 375/240.2, 375/240.03, 348/699, 382/238, 382/268, 382/250, 382/248, 341/51, 341/94
• US Class Current: 375/240.16
• CPC Class Codes: G06T 5/00 Image enhancement or restoration
• 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 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/527 Global motion vector estimation
• CPC Class Codes: H04N 19/573 Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction
• CPC Class Codes: H04N 19/577 Motion compensation with bidirectional frame interpolation, i.e. using B-pictures
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• 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 19/82 involving filtering within a prediction loop
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness
• CPC Class Codes: H04N 19/895 in combination with error concealment

Abstract

Adjacent blocks are identified in an image. Coding parameters for the adjacent blocks are identified. Deblock filtering between the identified adjacent blocks is skipped if the coding parameters for the identified adjacent blocks are similar and not skipped if the coding parameters for the identified adjacent blocks are substantially different.

Claims

1. A method for encoding an image, comprising:

identifying adjacent blocks in the image;

identifying coding parameters for the adjacent blocks;

skipping deblock filtering between the identified adjacent blocks when the coding parameters for the identified adjacent blocks are similar;

deblock filtering between the identified adjacent blocks when the coding parameters for the identified adjacent blocks are not similar;

identifying transform coefficients for the adjacent blocks;

skipping deblock filtering between the adjacent blocks when the transform coefficients are similar;

identifying D.C. components in the transform coefficients;

skipping deblock filtering between the adjacent blocks when the D.C. components are the same or similar;

identifying A.C. components in the transform coefficients; and

skipping deblock filtering between the adjacent blocks when the D.C. and A.C. components are the same or similar.

2. An encoder for encoding an image, comprising:

a processor adapted to identify adjacent blocks in the input image;

compare coding parameters for the adjacent blocks;

enable and disable filtering of blocking artifacts between the adjacent blocks according to the comparisons;

skip deblock filtering according to D.C. components in the residual coefficients; and

skip deblock filtering according to D.C. and A.C. components in the residual coefficients.

3. An encoder for encoding an image, comprising:

a processor adapted to identify adjacent blocks in the input image;

compare coding parameters for the adjacent blocks;

enable and disable filtering of blocking artifacts between the adjacent blocks according to the comparisons;

compare blocks in the image with reference frames, transform the result of the comparison between the reference frames and the blocks into transformed blocks having transform coefficients, compare the transform coefficients and encoding parameters of adjacent blocks, and skip deblock filtering between adjacent blocks in the image according to the results of the comparison between the transform coefficients and encoding parameters.

4. An encoder according to claim 3 wherein the transform coefficients include D.C. transform components and the encoding parameters include motion vectors and reference frames.

5. A decoder for decoding an encoded image, comprising:

a processor adapted to identify adjacent blocks in the encoded image;

identify coding parameters for the adjacent blocks;

enable or disable filtering of blocking artifacts between the adjacent blocks according to the coding parameters for the adjacent blocks;

identify residual coefficients for the adjacent blocks and skip deblock filtering between the adjacent blocks according to the identified residual coefficients;

identify D.C. components in the residual coefficients and skip deblock filtering between the adjacent blocks according to the identified D.C. components; and

identify similar A.C. components in the residual coefficients and skip deblock filtering between the identified adjacent according to the identified D.C. and A.C. components.