| CPC H04N 19/503 (2014.11) [H04N 19/176 (2014.11); H04N 19/188 (2014.11); H04N 19/70 (2014.11)] | 10 Claims |

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1. An image decoding method performed by an image decoding apparatus, the image decoding method comprising:
obtaining weight information related to a weight from a bitstream according to a weight parameter syntax structure, wherein the weight information includes first syntax elements and second syntax elements; and
decoding a current block by performing inter prediction based on the weight information,
wherein the decoding the current block comprises:
deriving prediction samples of the current block based on the weight information; and
decoding the current block based on residual samples of the current block and the prediction samples,
wherein the obtaining the weight information according to the weight parameter syntax structure comprises:
obtaining weight number information related to a number of the first syntax elements and a number of the second syntax elements obtained from the bitstream according to the weight parameter syntax structure; and
obtaining the first syntax elements and the second syntax elements from the weight parameter syntax structure based on the weight number information,
wherein the first syntax elements specify a difference of a weighting factor,
wherein the second syntax elements include a syntax element specifying an additive offset applied to a luma prediction value and a syntax element specifying a difference of an additive offset applied to a chroma prediction value,
wherein the weight number information is obtained from the bitstream according to the weight parameter syntax structure based on flag information obtained from the bitstream,
wherein the flag information specifies whether the weight number information is obtained from the bitstream by the weight parameter syntax structure.
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