Method of coding artifacts reduction

• US 7,027,661 B2
• Filed: 11/26/2001
• Issued: 04/11/2006
• Est. Priority Date: 11/27/2000
• Status: Expired due to Fees

• Current Assignee: Sony Deutschland GmbH (Sony Group Corp.)
• Original Assignee: Sony Limited (Sony Group Corp.)
• Inventors: Unruh, Christian, Wagner, Peter, Estevez, Miguel
• Primary Examiner(s): Mehta, Bhavesh M.
• Assistant Examiner(s): Kassa, Yosef
• Application Number:
  US09/995,290
• Publication Number:
  US 20020118399A1
• Time in Patent Office: 1,597 Days
• Field of Search: 382/233, 382/235, 382/236, 382/239, 382/243, 382/248, 382/252, 382/260, 382/261, 382/274, 382/275, 358/3.26, 358/3.27, 358/463, 358/326
• US Class Current: 382/275
• 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 19/136 Incoming video signal characteristics or properties
• 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 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/16 for a given display mode, e.g. for interlaced or progressive display mode
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/169 characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• 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 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• 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 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

A method to reduce coding artifacts within a discrete decoded picture includes a spatial and/or temporal filtering with respective filter characteristics dependent on an image quality value (Q). Preferably, the spatial filtering includes a deblocking filtering, wherein the deblocking filter operation decreases with an increasing image quality value (Q) and/or the deblocking filtering chooses a image quality value (Q) dependent weighting function for a pixel to be filtered according to an activity of both blocks to which common border said pixel belongs.

Claims

1. Method to reduce coding artifacts within a discrete decoded picture, said method comprising the steps of:

spatial and/or temporal filtering with respective filter characteristics dependent on an image quality value,

wherein said spatial filtering includes a deblocking filtering,

wherein the deblocking filter operation decreases with an increasing image quality value,

wherein said deblocking filtering chooses an activity-dependent weighting function for a pixel to be filtered according to a image quality value, and

wherein the activity of both blocks to which common border said pixel belongs is considered.

2. Method according to claim 1, wherein said weighting function is only applied to said pixel to be filtered if a blocking artifact is detected.

3. Method according to claim 1, wherein said deblocking filtering is performed separately for horizontal and vertical borders of neigh boring blocks.

4. Method according to claim 1, wherein said spatial filtering includes a deringing filtering, wherein the deringing filter operation decreases with an increasing image quality value.

5. Method according to claim 4, wherein said deringing filtering chooses a image quality value dependant deringing mask for a pixel to be filtered.

6. Method according to claim 5, wherein said deringing mask is only applied to said pixel to be filtered if said pixel belongs to a homogenous area.

7. Method according to claim 4, wherein said deringing filtering is a two dimensional filtering taking only neighboring pixels of said pixel to be filtered into account which belong to a same region.

8. Method according to claim 1, wherein the temporal filter operation decreases with an increasing image quality value.

9. Method according to claim 8,

wherein the temporal filter operation is claimed with a blending filter applied to an entire frame which determines a new frame as a weighted sum of a predicted frame and an actual frame, which weighting is dependent on said image quality value and a difference of the actual frame with She predicted frame.

10. Method according to claim 9, wherein said predicted frame is determined on basis of a motion compensation of a previously determined new frame.

11. Method according to claim 1, wherein said image quality value is determined based on a quantization scaling factor used for encoding the picture.

12. Method according to claim 1, wherein said image quality value is determined based on a user selection.

13. Method according to claim 1, wherein said discrete encoding/decoding of the picture is based on a discrete cosine transform.

14. Method according to claim 1, wherein said discrete encoding/decoding of the picture is based on a MPEG coding scheme.

15. Method to reduce coding artifacts within a discrete decoded picture, said method comprising the steps of:

spatial and/or temporal filtering with respective filter characteristics dependent on an image quality value,

wherein said spatial filtering includes a deringing filtering,

wherein the deringing filter operation decreases with an increasing image quality value, and

wherein said deringing filtering is a two dimensional filtering taking only neighboring pixels of said pixel to be filtered into account which belong to a same region.

17. Method according to claim 15, wherein said predicted frame is determined on basis of a motion compensation of a previously determined new frame.

16. Method to reduce coding artifacts within a discrete decoded picture, said method comprising the steps of:

spatial and/or temporal filtering with respective filter characteristics dependent on an image quality value,

wherein the temporal filter operation decreases with an increasing image quality value, and

wherein the temporal filter operation is realized with a blending filter applied to an entire frame which determines a new frame as a weighted sum of a predicted frame and an actual frame, which weighting is dependent on said image quality value and a difference of the actual frame with the predicted frame.