Image encoding method and device, and decoding method and device therefor
A video encoding method and apparatus and a video decoding method and apparatus. In the video encoding method, a first predicted coding unit of a current coding unit that is to be encoded is produced, a second predicted coding unit is produced by changing a value of each pixel of the first predicted coding unit by using each pixel of the first predicted coding unit and at least one neighboring pixel of each pixel, and the difference between the current coding unit and the second predicted coding unit is encoded, thereby improving video prediction efficiency.
1. A method of encoding video, the method comprising:
splitting a current picture into a plurality of maximum coding units, according to information about a maximum size of a coding unit;
splitting a maximum coding unit hierarchically into one or more coding units of depths including at least one of a current depth and a lower depth according t split information, the splitting the maximum coding unit further comprising:
when the split information indicates a split for a coding unit of the current depth, obtaining a coding unit of a lower depth which is one of rectangular data unit split from a coding unit a current depth, and
when the split information indicates a non-split for the coding unit of the current depth, obtaining at least one prediction unit from the coding unit of the current depth;
obtaining a first predicted value of a current prediction unit by using neighboring pixels of the current prediction unit; and
obtaining a second predicted value of pixels of the current prediction unit located on a top border and a left border of the current prediction unit by using the obtained first predicted value and at least one neighboring pixel,
wherein the second predicted value of the current prediction unit is obtained by using a weighted value of the obtained first predicted value and the at least one neighboring pixel.
2. The method of claim 1 , wherein, if a size of the current prediction unit is m x n, the first predicted value of a first pixel, which is to be changed and is located at an i th column and a j th row of the current prediction unit , is f[i][j], and values of two neighboring pixels selected from among neighboring pixels f[i][j−1], f[i−1][j], f[i+1][j], f[i][j+1], f[i−1][j+1], f[i+1][j−1], f[i−1][j−1], and f[i+1][j+1] of the first pixel are f 1 and f 2 , respectively, then the obtaining the second predicted value of pixels of the current prediction unit further comprises changing the value of the first pixel to f[i][j] by using a following equation:
f
′
[
i
]
[
j
]
=
f
1
+
f
2
+
2
*
f
[
i
]
[
j
]
4
,
wherein m and n denote positive integers.
3. The method of claim 1 , wherein, if a size of the current prediction unit is m x n, the first predicted value of a first pixel located on an i th column and a j th row of the current coding unit is f[i][j], a value of a pixel, which is located at the same j th row as the first pixel from among pixels included in a border region adjacent to the top of the current prediction unit, is f[−i][j], and a value of a pixel, which is located at the same i th column as the first pixel from among pixels included in a border region adjacent to the left of the current prediction unit, is f[i][−j], then the obtaining the second predicted value of pixels of the current prediction unit comprises changing the value of the first pixel to f[i][−j] by using a following equation:
f
′
[
i
]
[
j
]
=
2
f
[
i
]
[
j
]
+
f
[
i
]
[
-
1
]
+
f
[
-
1
]
[
j
]
4
,
wherein m and n are positive integers.
4. A method of decoding video, the method comprising:
splitting a current picture into a plurality of maximum coding units, according to information about a maximum size of a coding unit;
splitting a maximum coding unit hierarchically into one or more coding units of depths including at least one of a current depth and a lower depth according to split information, the splitting the maximum coding unit further comprising:
when the split information indicates a split for a coding unit of the current depth, obtaining a coding unit of a lower depth which is one of rectangular data unit split from a coding unit of a current depth, and
when the split information indicates a non-split for the coding unit of the current depth, obtaining at least one prediction unit from the coding unit of the current depth;
obtaining a first predicted value of a current prediction unit included in the at least one prediction unit by using neighboring pixels of the current prediction unit; and
obtaining a second predicted value of pixels of the current prediction unit located on a top border and a left border of the current prediction unit by using the obtained first predicted value and at least one neighboring pixel,
wherein the second predicted value of the current prediction unit is obtained by using a weighted value of the obtained first predicted value and the at least one neighboring pixel.
5. The method of claim 4 , wherein, if a size of the current prediction unit is m x n, the first predicted value of a first pixel, which is to be changed and is located at an i th column and a j th row of the current prediction unit, is f[i][j], and values of two neighboring pixels selected from among neighboring pixels f[i][j−1], f[i−1][j], f[i+1][j], f[i][j+1], f[i−1][j+1], f[i+1][j−1], f[i−1][j−1], and f[i+1][j+1] of the first pixel are f 1 and f 2 , respectively, then the obtaining the second predicted value of pixels of the current prediction unit further comprises changing the value of the first pixel to f[i][j]by using a following equation:
f
′
[
i
]
[
j
]
=
f
1
+
f
2
+
2
*
f
[
i
]
[
j
]
4
,
wherein m and n are positive integers.
6. The method of claim 4 , wherein, if a size of the current prediction unit is m x n, the first predicted value of a first pixel located on an i th column and a j th row of the current coding unit is f[i][j], a value of a pixel, which is located at the same i th row as the first pixel from among pixels included in a border region adjacent to the top of the current prediction unit, is f[−i][j], and a value of a pixel, which is located at the same i th column as the first pixel from among pixels included in a border region adjacent to the left of the current prediction unit, is f[i][−j], then the obtaining the second predicted value of pixels of the current prediction unit comprises changing the value of the first pixel to f[i][j] by using a following equation:
f
′
[
i
]
[
j
]
=
2
f
[
i
]
[
j
]
+
f
[
i
]
[
-
1
]
+
f
[
-
1
]
[
j
]
4
,
wherein m and n are positive integers.