Adaptive filtering based upon boundary strength

• US 7,787,542 B2
• Filed: 08/02/2006
• Issued: 08/31/2010
• Est. Priority Date: 09/14/2001
• Status: Expired due to Term

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Katata, Hiroyuki, Sun, Shijun, Lei, Shawmin
• Primary Examiner(s): LEE, Y YOUNG
• Application Number:
  US11/497,431
• Publication Number:
  US 20060268988A1
• Time in Patent Office: 1,490 Days
• Field of Search: 375/240.01, 375/240.12, 375/240.16, 375/240.18, 375/240.29
• US Class Current: 375/240.29
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• 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 19/124 Quantisation
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/137 Motion inside a coding unit, e.g. average field, frame or block difference
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• 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 19/15 by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/167 Position within a video image, e.g. region of interest [ROI]
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• 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 19/197 including determination of the initial value of an encoding parameter H04N19/56 takes precedence
• CPC Class Codes: H04N 19/43 Hardware specially adapted for motion estimation or compensation
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• 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 19/58 Motion compensation with long-term prediction, i.e. the reference frame for a current frame not being the temporally closest one H04N19/23 takes precedence
• CPC Class Codes: H04N 19/60 : using transform coding
• CPC Class Codes: H04N 19/61 : in combination with predictive coding
• CPC Class Codes: H04N 19/615 : using motion compensated temporal filtering [MCTF]
• CPC Class Codes: H04N 19/82 : involving filtering within a prediction loop
• CPC Class Codes: H04N 19/85 : using pre-processing or post-processing specially adapted for video compression
• CPC Class Codes: H04N 19/86 : involving reduction of coding artifacts, e.g. of blockiness

Abstract

Adjacent regions are identified in an image. Coding parameters for the adjacent regions are identified. Selective filtering is performed at the region between the identified adjacent regions.

Claims

1. An encoder for encoding an image with selectively filtering a boundary between two adjacent blocks in a reconstructed image, comprising:

motion compensation predictor for conducting motion compensation prediction for each of blocks to be encoded by using the reconstructed image, and

transformer for transforming data of the block to be encoded, wherein

filtering is not conducted for the boundary when

(1) both the two adjacent blocks are predicted from a reference frame;

(2) both the two adjacent blocks do not include any non-zero transform coefficients; and

(3) motion vectors of the two adjacent blocks satisfy a specified condition, said specified condition including;

|V(j,x)−

V(k,x)|<

1 pixel and |V(j,y)−

V(k,y)|<

1 pixel, where j and k are block numbers of adjacent blocks, V(j,x) and V(j,y) are components of the motion vector for block j, V(k,x), and V(k,y) are components of the motion vector for block k, x indicates horizontal direction of the motion vectors and y indicates vertical direction of the motion vectors.

2. The encoder of claim 1, wherein the specified condition is that the two motion vectors are identical with each other.

3. The encoder of claim 1, wherein the specified condition is that an absolute difference between the two motion vectors is less than a non-zero threshold.

4. A decoder for decoding an image with selectively filtering a boundary between two adjacent blocks in a reconstructed image, comprising:

motion compensation predictor for conducting motion compensation prediction for each of blocks to be decoded by using the reconstructed image, and

inverse transformer for inversely transforming data of each of the blocks to be decoded, wherein

the filtering is not conducted for the boundary when

(1) both the two adjacent blocks are predicted from a reference frame;

(2) both the two adjacent blocks do not include any non-zero transform coefficients; and

(3) motion vectors of the two adjacent blocks satisfy a specified condition, said specified condition including;

|V(j,x)−

V(k,x)|<

1 pixel and |V(j,y)−

V(k,y)|<

1 pixel, where j and k are block numbers of adjacent blocks, V(j,x) and V(j,y) are components of the motion vector for block j, V(k,x), and V(k,y) are components of the motion vector for block k, x indicates horizontal direction of the motion vectors and y indicates vertical direction of the motion vectors.

5. The decoder of claim 4, wherein the specified condition is that the two motion vectors are identical with each other.

6. The decoder of claim 4, wherein the specified condition is that an absolute difference between the two motion vectors is less than a non-zero threshold.

7. An encoding process for encoding an image with selectively filtering a boundary between two adjacent blocks in a reconstructed image, comprising:

step for conducting motion compensation prediction, with a motion compensation predictor, for each of blocks to be encoded by using the reconstructed image, and

step for transforming, with a transformer, data of the block to be encoded, wherein

filtering is not conducted for the boundary when

(1) both the two adjacent blocks are predicted from a reference frame;

(2) both the two adjacent blocks do not include any non-zero transform coefficients; and

(3) motion vectors of the two adjacent blocks satisfy a specified condition, said specified condition including;

|V(j,x)−

V(k,x)|<

1 pixel and |V(j,y)−

V(k,y)|<

1 pixel, where j and k are block numbers of adjacent blocks, V(j,x) and V(j,y) are components of the motion vector for block j, V(k,x), and V(k,y) are components of the motion vector for block k, x indicates horizontal direction of the motion vectors and y indicates vertical direction of the motion vectors.

8. The encoding process of claim 7, wherein the specified condition is that the two motion vectors are identical with each other.

9. The encoding process of claim 7, wherein the specified condition is that an absolute difference between the two motion vectors is less than a non-zero threshold.

10. The encoding process of any one of claims 7 to 9, wherein decision not to conduct the filtering is based on only a luminance component and, when filtering is not conducted for a boundary of blocks of a luminance component, filtering is not conducted also for a boundary of blocks of a chrominance component corresponding to the blocks of the luminance component.

11. The encoding process of claim 8, wherein decision not to conduct the filtering is made separately for a luminance component and for a chrominance component.

12. An decoding process for decoding an image with selectively filtering a boundary between two adjacent blocks in a reconstructed image, comprising:

step for conducting motion compensation prediction, with a motion compensation predictor, for each of blocks to be decoded by using the reconstructed image, and

step for inversely transforming, with an inverse transformer, data of the block to be decoded, wherein

filtering is not conducted for the boundary when

(1) both the two adjacent blocks are predicted from a reference frame;

(2) both the two adjacent blocks do not include any non-zero transform coefficients; and

(3) motion vectors of the two adjacent blocks satisfy a specified condition, said specified condition including;

|V(j,x)−

V(k,x)|<

1 pixel and |V(j,y)−

V(k,y)|<

1 pixel, where j and k are block numbers of adjacent blocks, V(j,x) and V(j,y) are components of the motion vector for block j, V(k,x), and V(k,y) are components of the motion vector for block k, x indicates horizontal direction of the motion vectors and y indicates vertical direction of the motion vectors.

13. The decoding process of claim 12, wherein the specified condition is that the two motion vectors are identical with each other.

14. The decoding process of claim 12, wherein the specified condition is that an absolute difference between the two motion vectors is less than a non-zero threshold.