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 whether 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 a motion vector of the current block as to be equal to a motion vector of the selected merge candidate;

generating a prediction sample of the current block based on the motion vector of the current block; and

generating a residual sample of the current block 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 vector is one of L0 motion vector for forward prediction, L1 motion vector for backward prediction, and Bi motion vector for bi prediction.

5. The method of claim 2 , wherein decoding the received mode information comprises:

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 decoding apparatus, comprising:

an entropy decoder configured to receive mode information on an inter prediction of a current block and residual information, wherein the mode information includes merge flag information indicating whether an inter prediction mode for the current block is a merge mode;

a predictor configured to derive merge candidates of the current block based on neighboring blocks of the current block, to select a merge candidate from the derived merge candidates, to determine a motion vector of the current block as to be equal to a motion vector of the selected merge candidate, and to generate a prediction sample of the current block based on the motion vector of the current block; and

an inverse transformer configured to generating a residual sample of the current block, wherein the residual sample is generated 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.

9. The apparatus 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 received prior to the merge flag information.

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

11. The apparatus of claim 9 , wherein the derived motion vector is one of L0 motion vector for forward prediction, L1 motion vector for backward prediction, and Bi motion vector for bi prediction.

12. The apparatus of claim 9 , wherein decoding the received mode information comprises:

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.

13. The apparatus 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 apparatus 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.