Method for encoding and decoding images, and device using same

1. A video decoding method performed by a decoding apparatus, comprising:

receiving mode information on an inter prediction of a current block and residual information, wherein the mode information includes merge flag information indicating an inter prediction mode for the current block is a merge mode;

deriving merge candidates of the current block based on neighboring blocks of the current block;

selecting a merge candidate from the derived merge candidates;

determining motion information of the current block as to be equal to motion information of the selected merge candidate;

deriving a prediction sample of the current block based on the motion information of the current block; and

reconstructing a picture based on the prediction sample and a residual sample derived based on the residual information,

wherein the neighboring blocks includes a left neighboring block, an upper neighboring block, an upper-right corner neighboring block, an upper-left corner neighboring block, and a lower-left corner neighboring block of the current block.

2. The method of claim 1 , wherein the mode information includes residual flag information indicating whether there is the residual information for the current block, and

wherein the residual flag information is received prior to the merge flag information.

3. The method of claim 2 , wherein the merge candidates has the same configuration regardless whether there is the residual information for the current block.

4. The method of claim 2 , wherein the derived motion information is one of L 0 motion information for forward prediction, L 1 motion information for backward prediction, and Bi motion information for bi prediction.

5. The method of claim 2 , further comprising:

decoding the merge flag information prior to the residual flag information; and

decoding the residual flag information only when the decoded merge flag information indicates that the inter prediction mode for the current block is the merge mode.

6. The method of claim 1 , wherein the left neighboring block is a bottom-most block among left neighboring blocks adjacent to the left boundary of the current block, and the top neighboring block is a right-most block among upper neighboring blocks adjacent to the upper boundary of the current block.

7. The method of claim 1 , wherein the neighboring blocks further includes a temporal neighboring block which is a block corresponding to the current block and located in a reference picture.

8. A video encoding method performed by an encoding apparatus, comprising:

deriving merge candidates of a current block based on neighboring blocks of the current block;

selecting a merge candidate from the derived merge candidates;

determining a motion information of the current block as to be equal to a motion information of the selected merge candidate;

deriving a prediction sample of the current block based on the motion information of the current block;

deriving a residual sample based on the derived prediction sample;

generating residual information based on the residual sample;

generating mode information of the current block, wherein the mode information includes merge flag information indicating an inter prediction mode for the current block is a merge mode; and

transmitting the mode information and the residual information,

wherein the neighboring blocks includes a left neighboring block, an upper neighboring block, an upper-right corner neighboring block, an upper-left corner neighboring block, and a lower-left corner neighboring block of the current block.

9. The method of claim 8 , wherein the mode information includes residual flag information indicating whether there is the residual information for the current block, and

wherein the residual flag information is transmitted prior to the merge flag information.

10. The method of claim 9 , wherein the merge candidates has the same configuration regardless whether there is the residual information for the current block.

11. The method of claim 9 , wherein the derived motion information is one of L 0 motion information for forward prediction, L 1 motion information for backward prediction, and Bi motion information for bi prediction.

12. The method of claim 9 , wherein the merge flag information is generated the prior to the residual flag information, and

wherein the residual flag information is generated only when the merge flag information indicates that the inter prediction mode for the current block is the merge mode.

13. The method of claim 8 , wherein the left neighboring block is a bottom-most block among left neighboring blocks adjacent to the left boundary of the current block, and the top neighboring block is a right-most block among upper neighboring blocks adjacent to the upper boundary of the current block.

14. The method of claim 8 , wherein the neighboring blocks further includes a temporal neighboring block which is a block corresponding to the current block and located in a reference picture.

15. A non-transitory computer-readable storage medium storing video information comprising: residual information generated by deriving merge candidates of a current block based on neighboring blocks of the current block, for selecting a merge candidate from the derived merge candidates, by determining a motion information of the current block as to be equal to a motion information of the selected merge candidate, by deriving a prediction sample of the current block based on the motion information of the current block, by deriving a residual sample based on the derived prediction sample, by generating the residual information based on the residual sample; and mode information including merge flag information indicating an inter prediction mode for the current block is a merge mode, wherein the neighboring blocks includes a left neighboring block, an upper neighboring block, an upper-right corner neighboring block, an upper-left corner neighboring block, and a lower-left corner neighboring block of the current block.