Image encoding/decoding method and apparatus

1 . An image decoding method, comprising:

generating a prediction block of a current block based on a pre-defined prediction mode;

generating a residual block of the current block based on a predetermined transform type; and

reconstructing the current block based on the prediction block and the residual block,

wherein when the pre-defined prediction mode is a merge mode, generating the prediction block comprises:

generating a merge candidate list of the current block, the merge candidate list including a plurality of merge candidates;

deriving, based on a merge index of the current block indicating one of the plurality of merge candidates, motion information of the current block from the merge candidate list; and

performing inter prediction of the current block based on the derived motion information,

wherein the plurality of merge candidates includes a spatial merge candidate derived from a neighboring block spatially adjacent to the current block, the neighboring block including at least one of a top neighboring block, a left neighboring block, a top-right neighboring block, a bottom-left neighboring block, or a top-left neighboring block,

wherein a merge candidate from a motion information list is additionally inserted into the merge candidate list, and

wherein the motion information list is configured with motion information of one or more blocks which are decoded before the current block.

2 . The method of claim 1 , wherein the motion information list is updated based on the motion information of the current block only when the current block is a block having a last decoding order in a parallel merge region.

3 . The method of claim 2 , wherein the parallel merge region refers to a region which is configured with a plurality of coding blocks which are decoded independently of each other.

4 . The method of claim 1 ,

wherein the motion information of the current block includes at least one of a motion vector, a reference picture index, or prediction direction information, and

wherein performing the inter prediction of the current block comprises modifying the motion vector of the current block based on a predetermined difference motion vector (MVD).

5 . The method of claim 4 ,

wherein the difference motion vector includes a first difference motion vector in a first direction (MVD L0 ) and a second difference motion vector in a second direction (MVD L1 ), and

wherein the second difference motion vector in the second direction is set as a vector which has a same size as and a direction opposite to the first difference motion vector in the first direction.

6 . The method of claim 4 ,

wherein the motion vector is modified based on an encoding parameter of the current block, and

wherein the encoding parameter includes at least one of a prediction mode, the motion information, or a size of the current block.

7 . The method of claim 1 , wherein the transform type is determined based on information which is explicitly signaled from an encoding device and a table which is pre-defined in a decoding device.

8 . The method of claim 1 , wherein the transform type is implicitly derived based on at least one of a size, a shape, an intra prediction mode, or a component type of the current block.

9 . An image encoding method, comprising:

generating a prediction block of a current block based on a pre-defined prediction mode;

generating a residual block of the current block based on the prediction block; and

encoding residual data of the residual block,

wherein when the pre-defined prediction mode is a merge mode, generating the prediction block comprises:

generating a merge candidate list of the current block, the merge candidate list including a plurality of merge candidates;

determining motion information of the current block based on one of the plurality of merge candidates in the merge candidate list; and

performing inter prediction of the current block based on the determined motion information,

wherein a merge index indicating the one of the plurality of merge candidates is encoded into a bitstream,

wherein the plurality of merge candidates includes a spatial merge candidate derived from a neighboring block spatially adjacent to the current block, the neighboring block including at least one of a top neighboring block, a left neighboring block, a top-right neighboring block, a bottom-left neighboring block, or a top-left neighboring block,

wherein a merge candidate from a motion information list is additionally inserted into the merge candidate list, and

wherein the motion information list is configured with motion information of one or more blocks which are encoded before the current block.

10 . A computer readable recoding medium storing a bitstream encoded by an image encoding method, the image encoding method comprising:

generating a prediction block of a current block based on a pre-defined prediction mode;

generating a residual block of the current block based on the prediction block; and

encoding residual data of the residual block,

wherein when the pre-defined prediction mode is a merge mode, generating the prediction block comprises:

generating a merge candidate list of the current block, the merge candidate list including a plurality of merge candidates;

determining motion information of the current block based on one of the plurality of merge candidates in the merge candidate list; and

performing inter prediction of the current block based on the determined motion information,

wherein a merge index indicating the one of the plurality of merge candidates is encoded into the bitstream,

wherein the plurality of merge candidates includes a spatial merge candidate derived from a neighboring block spatially adjacent to the current block, the neighboring block including at least one of a top neighboring block, a left neighboring block, a top-right neighboring block, a bottom-left neighboring block, or a top-left neighboring block,

wherein a merge candidate from a motion information list is additionally inserted into the merge candidate list, and

wherein the motion information list is configured with motion information of one or more blocks which are encoded before the current block.