Image encoding/decoding method and device, and recording medium in which bitstream is stored

A method of encoding an image, the method comprising:

• determining whether a current block is adjacent to an upper boundary of a current coding tree block of the current block;
• deriving a spatial sub-block merge candidate of the current block based on a top neighboring block of the current block;
• deriving a temporal sub-block merge candidate of the current block based on a temporal neighboring block of the current block;
• determining sub-block merge information of the current block from a sub-block merge candidate list including the spatial sub-block merge candidate and the temporal sub-block merge candidate;
• deriving a prediction sample of the current block based on the sub-block merge information;
• deriving a residual sample of the current block based on the prediction sample;
• and
• encoding image information including prediction related information and residual information of the current block,
• based on the current block being adjacent to the upper boundary of the current coding tree block of the current block, the spatial sub-block merge candidate is determined based on a motion vector corresponding to a location adjacent to the upper boundary of a current coding tree block of the current block, and
• the location adjacent to the upper boundary of the current coding tree block comprises a lower-left location of the top neighboring block and a lower-right location of the top neighboring block.

A non-transitory storage medium storing a program which causes an image encoding method for generating a bitstream is performed when the program is performed, wherein the image encoding method including:

• determining whether a current block is adjacent to an upper boundary of a current coding tree block of the current block;
• deriving a spatial sub-block merge candidate of the current block based on a top neighboring block of the current block;
• deriving a temporal sub-block merge candidate of the current block based on a temporal neighboring block of the current block;
• determining sub-block merge information of the current block from a sub-block merge candidate list including the spatial sub-block merge candidate and the temporal sub-block merge candidate;
• deriving a prediction sample of the current block based on the sub-block merge information;
• deriving a residual sample of the current block based on the prediction sample;
• encoding image information including prediction related information and residual information of the current block;
• and
• generating the bitstream including the image information,
• based on the current block being adjacent to the upper boundary of the current coding tree block of the current block, the spatial sub-block merge candidate is determined based on a motion vector corresponding to a location adjacent to the upper boundary of a current coding tree block of the current block, and
• the location adjacent to the upper boundary of the current coding tree block comprises a lower-left location of the top neighboring block and a lower-right location of the top neighboring block.

A transmission method for image data, the method comprising:

• obtaining a bitstream of encoded image e information, wherein the encoded image information is generated based on determining whether a current block is adjacent to an upper boundary of a current coding tree block of the current block, deriving a spatial sub-block merge candidate of the current block based on a top neighboring block of the current block, deriving a temporal sub-block merge candidate of the current block based on a temporal neighboring block of the current block, determining sub-block merge information of the current block from a sub-block merge candidate list including the spatial sub-block merge candidate and the temporal sub-block merge candidate, deriving a prediction sample of the current block based on the sub-block merge information, deriving a residual sample of the current block based on the prediction sample, and encoding image information including prediction related information and residual information of the current block;
• and
• transmitting the image data comprising the bitstream,
• based on the current block being adjacent to the upper boundary of the current coding tree block of the current block, the spatial sub-block merge candidate is determined based on a motion vector corresponding to a location adjacent to the upper boundary of a current coding tree block of the current block, and
• the location adjacent to the upper boundary of the current coding tree block comprises a lower-left location of the top neighboring block and a lower-right location of the top neighboring block.