Adaptive filtering based upon boundary strength

• US 20060268988A1
• Filed: 08/02/2006
• Published: 11/30/2006
• Est. Priority Date: 09/14/2001
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Hiroyuki Katata, Shaw-Min Lei, Shijun Sun
• Inventors: Katata, Hiroyuki, Sun, Shijun, Lei, Shawmin
• Granted Patent: US 7,787,542 B2
• Time in Patent Office: Days
• US Class Current: 375/240.160
• 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. A method for at least one of encoding and decoding an image, said method comprising:

(a) identifying adjacent regions in said image;

(b) examining coding parameters for said adjacent regions;

(c) selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said coding parameters;

(d) identifying similarities between coding parameters in a luminance channel of said adjacent regions; and

(e) controlling filtering for both the luminance channel and a chrominance channel in said image according to said similarities.

2. A method for at least one of encoding and decoding an image, said method comprising:

(a) identifying adjacent regions in said image;

(b) examining coding parameters for said adjacent regions; and

(c) selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon whether at least one of said adjacent regions is intra-coded.

3. A method for at least one of encoding and decoding an image, comprising:

(a) identifying adjacent regions in said image;

(b) examining coding parameters for said adjacent regions; and

(c) selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon whether at least one of said adjacent regions is encoded with residuals.

4. A method for at least one of encoding and decoding an image, comprising:

(a) identifying adjacent regions in said image;

(b) examining coding parameters for said adjacent regions; and

(c) selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon determining whether at least two of said adjacent regions have an absolute difference of motion vectors that has a mathematical relationship to a threshold value.

5. The method of claim 4 wherein said absolute difference is in a first direction.

6. The method of claim 5 wherein said absolute difference is also in a second direction different than said first direction.

7. A method for at least one of encoding and decoding an image, comprising:

(a) identifying adjacent regions in said image;

(b) determining a boundary strength for said adjacent regions; and

(c) selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength,

wherein said boundary strength is a first value when at least one of said adjacent regions are intra-coded.

8. A method for at least one of encoding and decoding an image, comprising:

(a) identifying adjacent regions in said image;

(b) determining a boundary strength for said adjacent regions; and

(c) selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength, wherein said boundary strength is;

i) a first value when at least one of said adjacent regions is intra-coded, and ii) a second value when said adjacent regions are inter-coded and at least one of said adjacent regions contains non-zero transform coefficients.

9. A method for at least one of encoding and decoding an image, comprising:

(a) identifying adjacent regions in said image;

(b) determining a boundary strength for said adjacent regions; and

(c) selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength;

wherein, for inter-coded regions, said boundary strength is;

(i) a first value when at least one of said adjacent regions contains non-zero transform coefficients, and

(ii) a second value when said adjacent regions do not contain non-zero transform coefficients and are predicted based upon different reference frames.

10. A method for at least one of encoding and decoding an image, comprising:

(a) identifying adjacent regions in said image;

(b) determining a boundary strength for said adjacent regions; and

(c) selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength, wherein, for inter-coded regions with no non-zero transform coefficients, said boundary strength is;

(i) a first value when said adjacent regions are predicted based upon different reference frames, and

(ii) a second value when said adjacent regions are predicted based upon same reference frame and have an absolute difference of motion vector with vector components less than a threshold value.

11. An encoder for encoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) an examiner for examining coding parameters for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said coding parameters;

(d) a second identifier for identifying similarities between coding parameters in a luminance channel of said adjacent regions; and

(e) a filter controller for controlling said filter, wherein said filter is applied to said luminance channel and a chrominance channel based on said similarities.

12. An encoder for encoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) an examiner for examining coding parameters for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said coding parameters;

wherein said selectively filtering is based upon determining whether at least one of said adjacent regions is intra-coded.

13. An encoder for encoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) an examiner for examining coding parameters for said adjacent regions; and

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said coding parameters;

wherein said selectively filtering is based upon determining whether at least one of said adjacent regions is encoded with residuals.

14. An encoder for encoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) an examiner for examining coding parameters for said adjacent regions; and

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said coding parameters;

wherein said selectively filtering is based upon determining whether at least two of said adjacent regions have an absolute difference of motion vectors that is one of greater than or less than a threshold value.

15. The encoder of claim 14 wherein said absolute difference is in a first direction.

16. The encoder of claim 15 wherein said absolute difference is also in a second direction different than said first direction.

17. An encoder for encoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) a determiner for determining a boundary strength for said adjacent regions; and

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength, and

wherein said boundary strength is a first value when at least one of said adjacent regions are intra-coded.

18. An encoder for encoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) a determiner for determining a boundary strength for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength wherein said boundary strength is;

i) a first value when at least one of said adjacent regions is intra-coded, and

ii) a second value when said adjacent regions are inter-coded and at least one of said adjacent regions contains non-zero transform coefficients.

19. An encoder for encoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) a determiner for determining a boundary strength for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength, wherein, for inter-coded regions, said boundary strength is;

i) a first value when at least one of said adjacent regions contains non-zero transform coefficients, and

ii) a second value when said adjacent regions do not contain non-zero transform coefficients and are predicted based upon different reference frames.

20. An encoder for encoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) a determiner for determining boundary strength for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength wherein, for inter-coded regions with no non-zero transform coefficients, said boundary strength is;

(i) a first value when said adjacent regions are predicted based upon different reference frames, and

(ii) a second value when said adjacent regions are predicted based upon same reference frame and have an absolute difference of motion vector with vector components less than a threshold value.

21. A decoder for decoding an image comprising

(a) a first identifier for identifying adjacent regions in said image;

(b) an examiner for examining coding parameters for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said coding parameters;

(d) a second identifier for identifying similarities between coding parameters in a luminance channel of said adjacent regions; and

(e) a filter controller for controlling said filter, wherein said filter is applied to said luminance channel and a chrominance channel based on said similarities.

22. A decoder for decoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) an examiner for examining coding parameters for said adjacent regions; and

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said coding parameters;

wherein said selectively filtering is based upon determining whether at least one of said adjacent regions is intra-coded.

23. A decoder for decoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) an examiner for examining coding parameters for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said coding parameters;

wherein said selectively filtering is based upon determining whether at least one of said adjacent regions is encoded with residuals.

24. A decoder for decoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) an examiner for examining coding parameters for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said coding parameters;

wherein said selectively filtering is based upon determining whether at least two of said adjacent regions have an absolute difference of motion vectors that is greater than or less than a threshold value.

25. The decoder of claim 24 wherein said absolute difference is in a first direction.

26. The decoder of claim 25 wherein said absolute difference is also in a second direction different than said first direction.

27. A decoder for decoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) a determiner for determining a boundary strength for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength; and

wherein said boundary strength is a first value when at least one of said adjacent regions are intra-coded.

28. A decoder for decoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) a determiner for determining a boundary strength for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength wherein said boundary strength is;

i) a first value when at least one of said adjacent regions is intra-coded and

ii) a second value when said adjacent regions are inter-coded and at least one of said adjacent regions contains non-zero transform coefficients.

29. A decoder for decoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) a determiner for determining a boundary strength for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength,

wherein, for inter-coded regions, said boundary strength is;

(i) a first value when at least one of said adjacent regions contains non-zero transform coefficients; and

(ii) a second value when said adjacent regions do not contain non-zero transform coefficients and are predicted based upon different reference frames.

30. A decoder for decoding an image comprising:

(a) a first identifier for identifying adjacent regions in said image;

(b) a determiner for determining a boundary strength for said adjacent regions;

(c) a filter for selectively filtering at least a portion of said regions proximate a boundary between said adjacent regions based upon said boundary strength, wherein, for inter-coded regions with no non-zero transform coefficients, said boundary strength is;

i) a first value when said adjacent regions are predicted based upon different reference frames, and

ii) a second value when said adjacent regions are predicted based upon same reference frame and have an absolute difference of motion vector with vector components less than a threshold value.