CODING DISTORTION REMOVAL METHOD, VIDEO ENCODING METHOD, AND APPARATUS AND PROGRAM FOR THE SAME

• US 20070104269A1
• Filed: 12/21/2006
• Published: 05/10/2007
• Est. Priority Date: 11/29/2001
• Status: Active Grant

• Current Assignee: Godo Kaisha IP Bridge 1 (IP Bridge, Inc.)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: FOO, Teck Wee, SHEN, Sheng Mei, KADONO, Shinya, LEE, Chak Joo, XUE, Zhong
• Granted Patent: US 7,792,195 B2
• Time in Patent Office: Days
• US Class Current: 375/240.30
• CPC Class Codes: G06T 5/00 Image enhancement or restoration
• 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 19/112 according to a given display mode, e.g. for interlaced or progressive display mode
• 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 19/14 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 19/157 Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/16 for a given display mode, e.g. for interlaced or progressive display mode
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/174 the region being a slice, e.g. a line of blocks or a group of blocks
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/182 the unit being a pixel
• 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 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/61 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

Abstract

Mosaic-shaped block noise occurs when a compressed video signal is reproduced. This block noise is removed but removing block noise from every block using a deblocking filter imposes a significant load on the deblocking filter. This load is therefore reduced by determining whether coding distortion removal (deblocking) is necessary, and applying a deblocking filter only when needed.

Claims

1. A method for coding, on a block basis, an image segmented into a plurality of blocks, comprising:

decoding a coded block to obtain a decoded block,

determining a filter selection parameter that determines, using a quantization parameter, a threshold value to change a coding distortion removal method;

removing coding distortion in pixels on both sides of a block boundary between adjacent decoded blocks by applying a coding distortion removal method selected based on comparison of a difference value of pixels in adjacent decoded blocks with the threshold value determined based on the filter selection parameter; and

encoding the filter selection parameter to obtain a coded filter selection parameter.

2. The method of claim 1, wherein the selected coding distortion removal method sets a number of the pixels in the adjacent decoded blocks to which coding distortion removal is to be applied to zero when the difference value is no fewer than the threshold value, and does not apply coding distortion removal to the pixels in the adjacent decoded blocks.

3. The coding method of claim 1, wherein the coding distortion removal method comprises a method for changing a filtering strength based on the filter selection parameter.

4. The coding method of claim 1, wherein the quantization parameter comprises an average of the quantization parameters of adjacent decoded blocks.

5. The coding method of claim 1, further comprising locating the coded filter selection parameter in a slice header of a coded slice signal that is acquired by encoding the slice.

6. The coding method of claim 1, further comprising applying the coding distortion to the decoded block on a block basis.