Inter prediction method and apparatus therefor

An image encoding method comprising:

• constructing merging candidate list for a current block, wherein the merging candidate list includes spatial merging candidates;
• selecting a candidate from the merging candidate list;
• generating merge index information indicating the selected candidate from the merging candidate list;
• generating information on a parallel merge level which indicates a size of a parallel merging region;
• and
• encoding image information including the merge index information and the information on the parallel merge level,
• wherein the current block belongs to the parallel merging region, wherein the size of the parallel merging region is determined based on the information on the parallel merge level,
• wherein the current block is related to a prediction unit (PU), and the PU is one of PUs partitioned from a coding unit (CU),
• wherein for the PU, within the parallel merging unit region, the spatial merging candidates are identical to spatial merging candidates of a 2N×2N PU which has a same size as the parallel merging unit region, and
• wherein the spatial merging candidates of the 2N×2N PU which has the same size as the parallel merging unit region, are derived from a lower left corner neighboring block, a left neighboring block, an upper right corner neighboring block, an upper neighboring block and an upper left corner neighboring block of the parallel merging unit region.

A non-transitory decoder-readable storage medium storing encoded image information generated by constructing merging candidate list for a current block, wherein the merging candidate list includes spatial merging candidates, selecting a candidate from the merging candidate list, generating merge index information indicating the selected candidate from the merging candidate list, generating information on a parallel merge level which indicates a size of a parallel merging region, and encoding image information including the merge index information and the information on the parallel merge level, wherein the current block belongs to the parallel merging region, wherein the size of the parallel merging region is determined based on the information on the parallel merge level, wherein the current block is related to a prediction unit (PU), and the PU is one of PUs partitioned from a coding unit (CU), wherein for the PU, within the parallel merging unit region, the spatial merging candidates are identical to spatial merging candidates of a 2N×2N PU which has a same size as the parallel merging unit region, and wherein the spatial merging candidates of the 2N×2N PU which has the same size as the parallel merging unit region, are derived from a lower left corner neighboring block, a left neighboring block, an upper right corner neighboring block, an upper neighboring block and an upper left corner neighboring block of the parallel merging unit region.