Method and apparatus for encoding video, and method and apparatus for decoding video

Patent metadata

Field	Value
Publication number	US-9313502-B2
Application number	US-85768210-A
Country	US
Kind code	B2
Filing date	Aug 17, 2010
Priority date	Aug 17, 2009
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

Disclosed are method and apparatus for encoding and decoding an image which divides a current picture into blocks with various sizes and varies a number of intra prediction modes according to the sizes of the divided blocks.

First claim

What is claimed is:

1. A method of decoding an image, the method comprising:
extracting information about an intra prediction mode of a current block to be decoded, from a bitstream, the intra prediction mode indicating a particular direction among a plurality of directions, the particular direction being indicated by one of dx number in a horizontal direction and a fixed number in a vertical direction, and dy number in the vertical direction and a fixed number in the horizontal direction; and
performing intra prediction on the current block according to the intra prediction mode, the intra prediction comprising:
determining a number of neighboring pixels located on one side among a left side of the current block and an upper side of the current block according to a position of a current pixel and the one of dx number in the horizontal direction and the dy number in the vertical direction, where the dx and dy are integers according to the particular direction;
determining one of a location of a neighboring pixel located on the left side of the current block determined based on the dy number in the vertical direction and the fixed number in the horizontal direction and a location of a neighboring pixel located on the upper side of the current block determined based on the dx number in the horizontal direction and the fixed number in the vertical direction;
when the number of the neighboring pixels is 1, obtaining a prediction value of the current pixel based on the neighboring pixel; and
when the number of the neighboring pixels is 2, obtaining the prediction value of the current pixel based on a weighted average of the neighboring pixels,
wherein the dx number and the dy number are determined among {32, 26, 21, 17, 13, 9, 5, 2, 0, −2, −5, −9, −13, −17, −21, −26} according to the intra prediction mode of the current block,
wherein the fixed integar number is power of 2, and

wherein:
the image is split into a plurality of maximum coding units, according to information about a maximum size of a coding unit,
a maximum coding unit, from among the plurality of maximum coding units, is hierarchically split into one or more coding units of depths according to split information,
a coding unit of a current depth is one of rectangular data units split from a coding unit of an upper depth,
when the split information indicates a split for the current depth, the coding unit of the current depth is split into coding units of a lower depth, independently from neighboring coding units,
when the split information indicates a non-split of the current depth, one or more prediction units are obtained from the coding unit of the current depth, and
the weighted average is determined based on one of the dx number and the dy number, and the location of one or more neighboring pixels.

2. The method of claim 1 , wherein the intra prediction mode comprises a prediction mode performing prediction using N, N being integer, pixels of neighboring blocks previously decoded and restored, located on or close to an extended line.

3. The method of claim 2 , wherein the N pixels of neighboring blocks are pixels of a neighboring block adjacent to the current block or not encoded block.

4. The method of claim 1 , wherein, when sizes of coding units are roughly classified into at least three sizes N1×N1 (N1 is an integer), N2×N2 (N2 is an integer), and N3×N3 (N3 is an integer and N1<N2<N3), a number of intra prediction modes to be performed on the coding unit having the size of N2×N2 is greater than numbers of intra prediction modes to be performed on the coding units having the size of N1×N1 and N3×N3.

5. The method of claim 1 , wherein numbers of intra prediction modes to be performed on coding units having sizes of 4×4, 8×8, 16×16, 32×32, 64×64, and 128×128 are 17, 34, 34, 34, 5, and 5, respectively.

6. An apparatus for encoding an image, the apparatus comprising:
an intra prediction mode determiner which determines an intra prediction mode of a current block to be encoded, the intra prediction mode indicating a particular direction among a plurality of directions, the particular direction being indicated by one of dx number in a horizontal direction and a fixed number in a vertical direction, and dy number in the vertical direction and a fixed number in the horizontal direction; and
an intra prediction performer which performs intra prediction on the current block to be encoded by determining a number of neighboring pixels located on one side among a left side of the current block and an upper side of the current block according to a position of a current pixel and the one of the dx number in the horizontal direction and the dy number in the vertical direction, where dx and dy are integers according to the particular direction, determining one of a location of a neighboring pixel located on the left side of the current block determined based on the dy number in the vertical direction and the fixed number in the horizontal direction and a location of a neighboring pixel located on the upper side of the current block determined based on the dx number in the horizontal direction and the fixed number in the vertical direction, when the number of the neighboring pixels is 1, obtaining a prediction value of the current pixel based on the neighboring pixel, and when the number of the neighboring pixels is 2, obtaining the prediction value of the current pixel based on a weighted average of the neighboring pixels,
wherein the dx number and the dy number are determined among {32, 26, 21, 17, 13, 9, 5, 2, 0, −2, −5, −9, −13, −17, −21, −26 } according to the intra prediction mode of the current block,
wherein the fixed integer number is power of 2 and
wherein:
the image is split into a plurality of maximum coding units, according to information about a maximum size of a coding unit,
the maximum coding unit is hierarchically split into one or more coding units of depths according to split information,
a coding unit of a current depth is one of rectangular data units split from a coding unit of an upper depth,
when the split information indicates a split for the current depth, the coding unit of the current depth is split into coding units of a lower depth, independently from neighboring coding units,
when the split information indicates a non-split of the current depth, one or more prediction units are obtained from the coding unit of the current depth, and
the weighted average is determined based on one of the dx number and the dy number, and the location of one or more neighboring pixels.

Assignees

• Song Hak-Sup
• Min Jung-Hye
• Samsung Electronics Co Ltd

Inventors

• Song Hak-Sup
• Min Jung-Hye

Classifications

• H04N19/593

  involving spatial prediction techniques · CPC title

• H04N19/11 Primary

  among a plurality of spatial predictive coding modes · CPC title

• H04N19/176

  the region being a block, e.g. a macroblock · CPC title

• H04N19/44

  Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder · CPC title

• H04N19/96

  Tree coding, e.g. quad-tree coding · CPC title