Filtering of prediction units according to intra prediction direction

Patent metadata

Field	Value
Publication number	US-9693058-B2
Application number	US-201314396983-A
Country	US
Kind code	B2
Filing date	Apr 26, 2013
Priority date	Apr 26, 2012
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

A video coding or decoding method in which luminance and chrominance samples in a 4:4:4 format or a 4:2:2 format are predicted from other respective samples according to a prediction direction associated with blocks of samples to be predicted; comprises detecting a prediction direction in respect of a current block to be predicted; generating a predicted block of chrominance samples according to other chrominance samples defined by the prediction direction; if the detected prediction direction is substantially vertical, filtering the left column of samples in the predicted block of chrominance samples, or if the detected prediction direction is substantially horizontal, filtering the top row of samples in the predicted block of chrominance samples; and encoding a difference between the filtered predicted chrominance block and the actual chrominance block or applying a decoded difference to the filtered predicted chrominance block so as to encode or decode the block respectively.

First claim

The invention claimed is:

1. A video decoding method in which luminance and chrominance samples are arranged as plural coding units each comprising a block of luminance and chrominance samples, the method comprising:
selecting, for a particular coding unit, a size and shape of one or more prediction units each comprising luminance or chrominance samples from at least a subset of that coding unit, the selection of the prediction unit size and shape being the same for luminance samples and for chrominance samples;
detecting a prediction direction in respect of each prediction unit;
generating a predicted block of samples according to other samples defined by the prediction direction;
when the detected prediction direction is vertical, filtering, using a horizontally-oriented filter, only a left column of samples in the predicted block of samples, and when the detected prediction direction is horizontal, filtering, using a vertically-oriented filter, only a top row of samples in the predicted block of samples;
storing, in memory, decoded data associated with the predicted block of samples; and
combining the decoded data with the filtered samples in the predicted block of samples,
wherein the vertical prediction direction is at a first tolerance, n angle modes from a vertical mode, where n is an integer, and
wherein the horizontal prediction direction is at a second tolerance, n angle modes from a horizontal mode.

2. A method according to claim 1 , the method comprising:
applying a decoded difference to the filtered predicted block so as to encode the block.

3. A method according to claim 1 , the method comprising:
filtering one or both of the left column of samples in the predicted block of samples and the top row of samples in the predicted block of samples.

4. A method according to claim 3 , in which, in a DC mode in which a predicted sample is generated as a simple arithmetic mean of surrounding samples, the filtering step comprises:
filtering the left column of samples in the predicted block of samples and filtering the top row of samples in the predicted block of samples.

5. A method according to claim 3 , in which:
the luminance samples represent a luminance component and respective chrominance samples represent two chrominance components; and
the filtering step is applied to a subset of the three components, the subset being either one or two of the three components.

6. A method according to claim 5 , in which the subset consists of the luminance component.

7. A method according to claim 1 , in which each video image is encoded such that a prediction mode for chrominance samples of the image is the same as that applicable to corresponding luminance samples.

8. A method according to claim 1 , in which:
the luminance and chrominance samples are arranged as plural coding units each comprising a block of luminance and chrominance samples; and
the prediction unit is a block of luminance or chrominance samples representing at least a subset of a respective coding unit.

9. A method according to claim 1 , in which the samples are in a video format in which the chrominance samples have the same sampling rate as the luminance samples.

10. A method according to claim 9 , in which the video format is a 4:4:4 format.

11. A video encoding method in which luminance and chrominance samples are arranged as plural coding units each comprising a block of luminance and chrominance samples, the method comprising:
selecting, for a particular coding unit, a size and shape of one or more prediction units each comprising luminance or chrominance samples from at least a subset of that coding unit, the selection of the prediction unit size and shape being the same for luminance samples and for chrominance samples;
detecting a prediction direction in respect of each prediction unit;
generating a predicted block of samples according to other samples defined by the prediction direction;
when the detected prediction direction is vertical, filtering, using a horizontally-oriented filter, only a left column of samples in the predicted block of samples, and when the detected prediction direction is horizontal, filtering, using a vertically-oriented filter, only a top row of samples in the predicted block of samples;
storing, in memory, encoded data associated with the predicted block of samples; and
combining the encoded data with the filtered samples in the predicted block of samples,
wherein the vertical prediction direction is at a first tolerance, n angle modes from a vertical mode, where n is an integer, and
wherein the horizontal prediction direction is at a second tolerance, n angle modes from a horizontal mode.

12. A method according to claim 11 , the method comprising:
encoding a difference between the filtered predicted block and the block.

13. A video coding apparatus in which luminance and chrominance samples are arranged as plural coding units each comprising a block of luminance and chrominance samples, the video coding apparatus comprising:
selection circuitry configured to select, for a particular coding unit, a size and shape of one or more prediction units each comprising luminance or chrominance samples from at least a subset of that coding unit, the selection of the prediction unit size and shape being the same for luminance samples and for chrominance samples;
detection circuitry configured to detect a prediction direction in respect of each prediction unit;
generation circuitry configured to generate a predicted block of samples according to other samples defined by the prediction direction;
a horizontally-oriented filter configured to filter only a left column of samples in the predicted block of samples when the detected prediction direction is vertical;
a vertically-oriented filter configured to filter only a top row of samples in the predicted block of samples when the detected prediction direction is horizontal;
memory configured to store encoded data associated with the predicted block of samples; and
circuitry configured to combine the encoded data with the filtered samples in the predicted block of samples,
wherein the vertical prediction direction is at a first tolerance, n angle modes from a vertical mode, where n is an integer, and
wherein the horizontal prediction direction is at a second tolerance, n angle modes from a horizontal mode.

14. A video decoding apparatus in which luminance and chrominance samples are arranged as plural coding units each comprising a block of luminance and chrominance samples; the video decoding apparatus comprising:
selection circuitry configured to select, for a particular coding unit, a size and shape of one or more prediction units each comprising luminance or chrominance samples from at least a subset of that coding unit, the selection of the prediction unit size and shape being the same for luminance samples and for chrominance samples;
detection circuitry configured to detect a prediction direction in respect of each prediction unit;
generation circuitry configured to generate a predicted block of samples according to other samples defined by the prediction direction;
a horizontally-oriented filter configured to filter only a left column of samples in the predicted block of samples when the detected prediction direction is vertical;
a vertically-oriented filter configured to filter only a top row of samples in the predicted block of samples when the detected prediction direction is horizontal; and
memory configured to store decoded data associated with the predicted block of samples;
circuitry configured to combine the decoded data the filtered

Assignees

• Sony Corp

Inventors

• Gamei James Alexander
• Saunders Nicholas Ian
• Sharman Karl James
• Silcock Paul James

Classifications

• H04N19/122

  Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type · CPC title

• H04N19/103 Primary

  Selection of coding mode or of prediction mode · CPC title

• H04N19/157

  Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter · CPC title

• H04N19/13

  Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC] · CPC title

• H04N19/50

  using predictive coding (H04N19/61 takes precedence) · CPC title