Image coding/decoding method and apparatus therefor
Disclosed are an image coding/decoding method and an apparatus therefor. Specifically, a method for decoding an image by a decoding apparatus may include: deriving an intra prediction mode of a current block; configuring reference samples with samples neighboring to an upper end and samples neighboring to a left side of the current block; generating a prediction block of the current block by using the reference sample; and filtering a sample adjacent to a top boundary and/or a left boundary of the current block among the prediction samples, in which when the current block is a non-square block, whether to filter the sample adjacent to the top boundary of the current block may be determined by considering only a width of the current block and whether to filter the sample adjacent to the left boundary of the current block may be determined by considering only a height of the current block.
1. A method for decoding an image by a decoding apparatus, the method comprising:
deriving an intra prediction mode of a current block;
configuring reference samples with samples neighboring to an upper end and samples neighboring to a left side of the current block;
generating a prediction block of the current block by intra prediction using the reference samples and the derived intra prediction mode; and
filtering prediction samples of the current block based on the derived intra prediction mode and a size of the current block,
wherein when the derived intra prediction mode is mode 2 or modes 3 to 10 or less in the intra prediction mode method in which a total of 67 intra prediction modes are defined, the filtering of the prediction samples is performed based only on a width among the width and a height of the current block and on the derived intra prediction mode, and
wherein when the derived intra prediction mode is greater than or equal to 57 in the intra prediction mode method in which a total of 67 intra prediction modes
are defined, the filtering of the prediction samples is performed based only on the height among the width and the height of the current block and on the derived intra prediction mode.
2. The method of claim 1 , wherein when the intra prediction mode of the current block is a DC mode,
the filtering of the prediction samples adjacent to an upper boundary of the current block is performed based on that the width of the current block is equal to or less than a predetermined size, and
the filtering of the prediction samples adjacent to a left boundary of the current block is performed based on that the height of the current block is equal to or less than a predetermined size.
3. The method of claim 1 , wherein when a directionality of the intra prediction mode of the current block is within a predetermined range based on a horizontal intra prediction mode, the filtering of the prediction samples adjacent to an upper boundary of the current block is performed based on that the width of the current block is equal to or less than a predetermined size.
4. The method of claim 1 , wherein when a directionality of the intra prediction mode of the current block is within a predetermined range based on a vertical intra prediction mode, the filtering of the prediction samples adjacent to the left boundary of the current block is performed when the height of the current block is equal to or less than a predetermined size.
5. The method of claim 1 , wherein when the intra prediction mode of the current block is 2, prediction samples which belong to four lines adjacent to an upper boundary of the current block are filtered based on that the width of the current block is equal to or less than a predetermined size and the height of the current block is more than 4.
6. The method of claim 1 , wherein when the intra prediction mode of the current block is 2, only prediction samples which belong to two lines adjacent to an upper boundary of the current block are filtered based on that the width of the current block is equal to or less than a predetermined size and the height of the current block is not more than 4.
7. The method of claim 1 , wherein when the intra prediction mode of the current block is 66, prediction samples which belong to four lines adjacent to a left boundary of the current block are filtered based on that the height of the current block is equal to or less than a predetermined size and the width of the current block is more than 4.
8. The method of claim 1 , wherein when the intra prediction mode of the current block is 66, only prediction samples which belong to two lines adjacent to a left boundary of the current block are filtered based on that the height of the current block is equal to or less than a predetermined size and the width of the current block is not more than 4.
9. A decoding apparatus for decoding an image, the decoding apparatus comprising:
an intra prediction mode deriving unit to derive an intra prediction mode of a current block;
a reference sample configuring unit to configure reference samples with samples neighboring to an upper end and samples neighboring to a left side of the current block;
a prediction sample generating unit to generate a prediction block of the current block by intra prediction using the reference samples and the derived intra prediction mode; and
a prediction sample filtering unit to filter prediction samples of the current block based on the derived intra prediction mode and a size of the current block,
wherein when the derived intra prediction mode is mode 2 or modes 3 to 10 or less in the intra prediction mode method in which a total of 67 intra prediction modes are defined, the filtering of the prediction samples is performed based only on a width among the width and a height of the current block and on the derived intra prediction mode, and
wherein when the derived intra prediction mode is greater than or equal to 57 in the intra prediction mode method in which a total of 67 intra prediction modes are defined, the filtering of the prediction samples is performed based only on the height among the width and the height of the current block and on the derived intra prediction mode.