Method and apparatus for image intraprediction encoding/decoding
Provided is a method and apparatus for image intraprediction encoding/decoding. The method for image intraprediction encoding includes an intraprediction unit which divides an input block into at least one first sub-block of a predetermined size, and performing intraprediction encoding on the at least one first sub-block according to a first sub-block processing order using pixel values of at least adjacent sub-blocks located to the right of and/or below the at least one first sub-block.
1. A method of image intraprediction encoding, the method comprising:
dividing an input block into first sub-blocks of a predetermined size; and
performing intraprediction encoding on the first sub-blocks according to a first sub-block processing order using pixel values of at least one of an adjacent sub-block located to the right of the first sub-blocks and an adjacent sub-block located below the first sub-blocks,
wherein when the input block is divided into 16 sub-blocks, the first sub-block processing order is expressed as one of matrices
[
3
2
1
0
7
6
5
4
11
10
9
8
15
14
13
12
]
,
[
12
13
14
15
8
9
10
11
4
5
6
7
0
1
2
3
]
,
[
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
]
,
[
0
4
8
12
1
5
9
13
2
6
10
14
3
7
11
15
]
,
[
12
8
4
0
13
9
5
1
14
10
6
2
15
11
7
3
]
,
[
3
7
11
15
2
6
10
14
1
5
9
13
0
4
8
12
]
,
[
15
11
7
3
14
10
6
2
13
9
5
1
12
8
4
0
]
,
[
5
4
1
0
7
6
3
2
12
12
9
8
13
14
11
10
]
,
[
15
13
7
15
14
12
6
14
11
9
3
13
10
8
2
12
]
,
or
[
10
11
14
15
8
9
12
13
2
3
6
7
0
1
4
5
]
.
2. The method of claim 1 , wherein intraprediction directions in intraprediction according to the first sub-block processing order have different directivities to indicate pixels of adjacent blocks used for the intraprediction of current first sub-blocks.
3. The method of claim 1 , further comprising:
dividing the input block into second sub-blocks different in size than the first sub-blocks;
performing intraprediction encoding on the second sub-blocks; and
comparing a cost of the first sub-blocks and a cost of the second sub-blocks and determining a final intraprediction mode for the input block.
4. The method of claim 3 , wherein there are four of the second sub-blocks, the second sub-blocks are obtained by dividing the input block into four, and the second sub-blocks are intrapredicted according to one of second sub-block processing orders represented as matrices
[
3
0
1
2
]
,
[
2
0
3
1
]
,
[
1
0
3
2
]
,
[
3
1
2
0
]
,
[
3
2
1
0
]
,
[
2
3
0
1
]
,
and
[
1
3
0
2
]
.
5. The method of claim 3 , further comprising adding information about the determined intraprediction mode to a header of a bitstream of an encoded image.
6. An apparatus for image intraprediction encoding, the apparatus comprising an intraprediction unit dividing an input block into first sub-blocks of a predetermined size and performing intraprediction encoding on the first sub-blocks according to a first sub-block processing order using pixel values of at least one of an adjacent sub-block located to the right of the first sub-blocks and an adjacent sub-block located below the first sub-blocks,
wherein when the input block is divided into 16 sub-blocks, the first sub-block processing order is expressed as one of matrices
[
3
2
1
0
7
6
5
4
11
10
9
8
15
14
13
12
]
,
[
12
13
14
15
8
9
10
11
4
5
6
7
0
1
2
3
]
,
[
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
]
,
[
0
4
8
12
1
5
9
13
2
6
10
14
3
7
11
15
]
,
[
12
8
4
0
13
9
5
1
14
10
6
2
15
11
7
3
]
,
[
3
7
11
15
2
6
10
14
1
5
9
13
0
4
8
12
]
,
[
15
11
7
3
14
10
6
2
13
9
5
1
12
8
4
0
]
,
[
5
4
1
0
7
6
3
2
13
12
9
8
13
14
11
10
]
,
[
15
13
7
5
14
12
6
4
11
9
3
1
10
8
2
0
]
,
or
[
10
11
14
15
8
9
12
13
2
3
6
7
0
1
4
5
]
.
7. The apparatus of claim 6 , wherein intraprediction directions in intraprediction according to the first sub-block processing order have different directivities to indicate pixels of adjacent blocks used for the intraprediction of current first sub-blocks.
8. The apparatus of claim 6 , wherein the intraprediction unit comprises:
an intraprediction performing unit which divides the input block into second sub-blocks different in size than the first sub-blocks and performs intraprediction encoding on the second sub-blocks; and
a prediction mode determining unit which compares a cost of the first sub-blocks and a cost of the second sub-blocks and determines a final intraprediction mode for the input block.
9. The apparatus of claim 8 , wherein there are four of the second sub-blocks, the second sub-blocks are obtained by dividing the input block into four, and the second sub-blocks are intrapredicted according to one of second sub-block processing orders represented as matrices
[
3
0
1
2
]
,
[
2
0
3
1
]
,
[
1
0
3
2
]
,
[
3
1
2
0
]
,
[
3
2
1
0
]
,
[
2
3
0
1
]
,
and
[
1
3
0
2
]
.
10. The apparatus of claim 8 , wherein the prediction mode determining unit adds information about the determined intraprediction mode to a header of a bitstream of an encoded image.
11. A method of image intraprediction decoding in which a bitstream of an encoded image is received and intraprediction decoded, the method comprising:
extracting intraprediction mode information from the bitstream;
selecting, based on the extracted intraprediction mode information, at least one sub-block processing order that allows the use of pixel values of at least one of an adjacent sub-block to the right of and an adjacent sub-block below a current sub-block for intraprediction decoding; and
performing intraprediction decoding on sub-blocks according to the selected sub-block processing order, thereby forming a predicted block,
wherein the selected sub-block processing order is a sub-block processing order expressed as one of matrices
[
3
2
1
0
7
6
5
4
11
10
9
8
15
14
13
12
]
,
[
12
13
14
15
8
9
10
11
4
5
6
7
0
1
2
3
]
,
[
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
]
,
[
0
4
8
12
1
5
9
13
2
6
10
14
3
7
11
15
]
,
[
12
8
4
0
13
9
5
1
14
10
6
2
15
11
7
3
]
,
[
3
7
11
15
2
6
10
14
1
5
9
13
0
4
8
12
]
,
[
15
11
7
3
14
10
6
2
13
9
5
1
12
8
4
0
]
,
[
5
4
1
0
7
6
3
2
13
12
9
8
13
14
11
10
]
,
[
15
13
7
5
14
12
6
4
11
9
3
1
10
8
2
0
]
,
and
[
10
11
14
15
8
9
12
13
2
3
6
7
0
1
4
5
]
.
12. The method of claim 11 , wherein the intraprediction mode information includes information about the size of a predetermined block used for intraprediction.
13. An apparatus for image intraprediction decoding in which a bitstream of an encoded image is received and intraprediction decoded, the apparatus comprising:
an extracting unit which extracts intraprediction mode information from the bitstream; and
an intraprediction unit which selects, based on the extracted intraprediction mode information, at least one sub-block processing order that allows the use of pixel values of at least one of an adjacent sub-block to the right of a current sub-block for intraprediction decoding and an adjacent sub-block below the current sub-block for intraprediction decoding, and performing intraprediction decoding on sub-blocks according to the selected sub-block processing order, thereby forming a predicted block,
wherein the selected sub-block processing order a sub-block processing order expressed as one of matrices
[
3
2
1
0
7
6
5
4
11
10
9
8
15
14
13
12
]
,
[
12
13
14
15
8
9
10
11
4
5
6
7
0
1
2
3
]
,
[
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
]
,
[
0
4
8
12
1
5
9
13
2
6
10
14
3
7
11
15
]
,
[
12
8
4
0
13
9
5
1
14
10
6
2
15
111
7
3
]
,
[
3
7
11
15
2
6
10
14
1
5
9
13
0
4
8
12
]
,
[
15
11
7
3
14
10
6
2
13
9
5
1
12
8
4
0
]
,
[
5
4
1
0
7
6
3
2
13
12
9
8
13
14
11
10
]
,
[
15
13
7
5
14
12
6
4
11
9
3
1
10
8
2
0
]
,
or
[
10
11
14
15
8
9
12
13
2
3
6
7
0
1
4
5
]
.
14. The apparatus of claim 13 , wherein the intraprediction mode information includes information about the size of a predetermined block used for intraprediction.