Image decoding method and image encoding method using motion compensation, and transmission method for image data

An image encoding method performed by an encoding apparatus, the method comprising:

• determining that bi-prediction is applied to a current block;
• deriving motion information candidates based on neighboring blocks of the current block;
• deriving motion information of the current block based on at least one of the motion information candidates;
• generating predicted blocks of the current block based on the motion information of the current block;
• generating a predicted block of the current block based on weight information for the bi-prediction and the predicted blocks;
• generating information related to motion compensation;
• and
• encoding image information including the information related to the motion compensation,
• wherein the information related to motion compensation includes inter prediction indication information indicating that the bi-prediction is applied to the current block,
• wherein the motion information candidates include spatial candidates derived based on spatial neighboring blocks of the current block,
• wherein the information related to the motion compensation includes the weight information for the bi-prediction,
• wherein the weight information for the bi-prediction is signaled in a unit of coding unit,
• wherein the weight information for the bi-prediction indicates one of weight values including a negative weight value,
• wherein the weight information for the bi-prediction is based on a truncated unary binarization, and
• wherein the weight information for the bi-prediction is encoded based on a context model.

A transmission method for image data, the method comprising:

• obtaining a bitstream of encoded image information generated based on an image encoding method, wherein the image encoding method comprises determining that bi-prediction is applied to a current block, deriving motion information candidates based on neighboring blocks of the current block, deriving motion information of the current block based on at least one of the motion information candidates, generating predicted blocks of the current block based on the motion information of the current block, generating a predicted block of the current block based on weight information for the bi-prediction and the predicted blocks, generating information related to motion compensation, and encoding image information including the information related to the motion compensation;
• and
• transmitting the image data comprising the bitstream,
• wherein the information related to motion compensation includes inter prediction indication information indicating that the bi-prediction is applied to the current block,
• wherein the motion information candidates include spatial candidates derived based on spatial neighboring blocks of the current block,
• wherein the information related to the motion compensation includes the weight information for the bi-prediction,
• wherein the weight information for the bi-prediction is signaled in a unit of coding unit,
• wherein the weight information for the bi-prediction indicates one of weight values including a negative weight value,
• wherein the weight information for the bi-prediction is based on a truncated unary binarization, and
• wherein the weight information for the bi-prediction is encoded based on a context model.