Video decoding method and device for same and video encoding method and device for same

1. A video decoding method comprising:

obtaining a bitstream including residual data about a residual block of a current block;

determining a plurality of prediction directions with respect to the current block among a plurality of prediction direction candidates;

determining a plurality of reference samples included in a neighboring region of the current block in a current image, by using the plurality of prediction directions that are determined among the plurality of the prediction direction candidates;

generating a prediction block of the current block by using the plurality of reference samples;

obtaining a residual block of the current block based on the residual data about the residual block of the current block; and

reconstructing the current block by using the prediction block of the current block and the residual block of the current block,

wherein the determining of the plurality of prediction directions with respect to the current block comprises determining a first prediction direction in the current block and a second prediction direction in the current block, by using an anchor prediction direction which is indicated by an anchor sample from among samples of an anchor region,

wherein the samples of the anchor region include some samples of the neighboring region of the current block.

2. The video decoding method of claim 1 , wherein a difference between indices of two of the plurality of prediction directions is 1.

3. The video decoding method of claim 1 , wherein the determining of the plurality of prediction directions with respect to the current block comprises:

determining the first prediction direction of a first region in the current block, by using an anchor prediction direction of an anchor sample from among samples of an anchor region including some samples of the neighboring region of the current block; and

determining the second prediction direction of a second region in the current block by using the anchor prediction direction of the anchor sample.

4. The video decoding method of claim 3 , wherein the first region or the second region is a sample or an M×N block (M and N are integers).

5. The video decoding method of claim 1 , wherein the plurality of prediction directions with respect to the current block comprise the first prediction direction and a second prediction direction, and

the determining of the plurality of reference samples included in the neighboring region of the current block in a current image, by using the plurality of prediction directions that are determined, comprises:

determining a first reference sample by using the first prediction direction; and

determining a second reference sample by using the second prediction direction,

and the generating of the prediction block of the current block comprises:

generating a first prediction block of the current block by using the first reference sample;

generating a second prediction block of the current block by using the second reference sample; and

generating the prediction block by using the first prediction block and the second prediction block.

6. The video decoding method of claim 5 , further comprising:

obtaining, from the bitstream, information about the first prediction direction;

and

determining the second prediction direction by using the information about the first prediction direction.

7. The video decoding method of claim 3 , wherein the first prediction direction and the second prediction direction are determined by performing an interpolation based on a plurality of anchor prediction directions according to locations of the first region and the second region, which are apart from a location of a plurality of anchor samples which indicate the plurality of the anchor prediction directions.

8. The video decoding method of claim 3 , wherein a block including the

current block is hierarchically split to generate a transformation block having at least one transformation depth between a current transformation depth and a lower transformation depth, and the first region is one of the transformation block having at least one transformation depth between the current transformation depth and the lower transformation depth.

9. The video decoding method of claim 1 , wherein the current block is split in a horizontal direction or a vertical direction to generate a first block and a second block, and

the determining of the plurality of prediction directions with respect to the current block comprises:

determining the first prediction direction of a first region included in the first block and the second prediction direction of a second region included in the first block, by using an anchor prediction direction of an anchor sample from among samples of a first anchor region that includes some samples of a neighboring region of the first block; and

determining a third prediction direction of a third region included in the second block and a fourth prediction direction of a fourth region in the second block, by using an anchor prediction direction of an anchor sample from among samples of a second anchor sample that includes some samples of a neighboring region of the second block.

10. The video decoding method of claim 9 , wherein a filtering is performed with respect to prediction directions or prediction values of samples located around a boundary between the first block and the second block.

11. The video decoding method of claim 1 , further comprising

obtaining, from the bitstream, a flag indicating whether an intra prediction is performed on the current block based on one prediction direction or based on a plurality of prediction directions,

wherein the determining of the plurality of prediction directions with respect to the current block comprises:

when the flag indicates that the intra prediction is performed on the current block based on the plurality of prediction directions, determining the plurality of prediction directions, and

the determining of the plurality of reference samples included in the neighboring region of the current block in a current image, by using the plurality of prediction directions that are determined, comprises:

when the flag indicates that the intra prediction is performed on the current block based on the plurality of prediction directions, determining a plurality of reference samples included in a neighboring region of the current block in a current image, by using the determined plurality of prediction directions.

12. A video encoding method comprising:

performing an intra prediction on a current block based on a plurality of prediction direction candidates with respect to the current block;

determining a plurality of prediction directions among the plurality of the prediction direction candidates with respect to the current block based on the intra prediction on the current block;

generating a residual block of the current block by using a prediction block of the current block that is generated according to the determined plurality of prediction directions among the plurality of the prediction direction candidates with respect to the current block; and

generating a bitstream including data about the residual block,

wherein the performing of the intra prediction on the current block based on the plurality of prediction directions with respect to the current block comprises:

determining a plurality of reference samples included in a neighboring region of the current block in a current image, by using the plurality of prediction directions among the plurality of the prediction direction candidates with respect to the current block; and

generating the prediction block of the current block by using the plurality of reference samples,

wherein the determining of the plurality of prediction directions with respect to the current block comprises

determining a first prediction direction in the current block and a second prediction direction in the current block, by using an anchor prediction direction which is indicated by an anchor sample from among samples of an anchor region,

wherein the samples of the anchor region include some samples of the neighboring region of the current block.

13. The video encoding method of claim 12 , wherein the plurality of prediction direction candidates comprise the second prediction direction and a third prediction direction, wherein a difference between an index of one of the second prediction and the third prediction direction and an index of the first prediction direction is 1, the performing of the intra prediction on the current block based on the plurality of prediction direction candidates with respect to the current block comprises performing an intra prediction on the current block by using the first prediction direction and the second prediction direction among the plurality of the prediction candidates, and the determining of the plurality of prediction directions with respect to the current block comprises determining the first prediction direction and the second prediction direction among the plurality of the prediction candidates based on the intra prediction.

14. A video decoding apparatus comprising:

an obtainer configured to obtain a bitstream including residual data about a residual block of a current block;

an intra predictor configured to determine a plurality of prediction directions among a plurality of prediction direction candidates with respect to the current block, to determine a plurality of reference samples included in a neighboring region of the current block in a current image by using the determined plurality of prediction directions among the plurality of the prediction direction candidates, and to generate a prediction block of the current block by using the plurality of reference samples; and

an image decoder configured to obtain the residual block of the current block based on the residual data about the residual block of the current block, and to reconstruct the current block by using the residual block of the current block,

wherein when the intra predictor determines the plurality of prediction directions with respect to the current block, the intra predictor determines a first prediction direction in the current block and a second prediction direction in the current block, by using an anchor prediction direction which is indicated by an anchor sample from among samples of an anchor region,

wherein the samples of the anchor region include some samples of the neighboring region of the current block.

15. A video encoding apparatus comprising:

an intra predictor configured to perform an intra prediction on a current block based on a plurality of prediction direction candidates with respect to the current block,

and to determine a plurality of prediction directions among the plurality of the prediction direction candidates with respect to the current block based on the intra prediction on the current block; and

an image encoder configured to generate a residual block of the current block by using a prediction block of the current block that is generated according to the determined plurality of prediction directions among the plurality of the prediction direction candidates with respect to the current block, and to generate a bitstream including data about the residual block,

wherein the intra predictor is configured to determine a plurality of reference samples included in a neighboring region of the current block in a current image by using the plurality of prediction directions among the plurality of the prediction direction candidates with respect to the current block, and to generate the prediction block of the current block by using the plurality of reference samples,

wherein when the intra predictor determines the plurality of prediction directions with respect to the current block, the intra predictor determines a first prediction direction in the current block and a second prediction direction in the current block, by using an anchor prediction direction which is indicated by an anchor sample from among samples of an anchor region,

wherein the samples of the anchor region include including some samples of the neighboring region of the current block.