| CPC H04N 19/176 (2014.11) [H04N 19/12 (2014.11); H04N 19/132 (2014.11); H04N 19/70 (2014.11)] | 12 Claims |
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1. An image decoding method performed by a decoding apparatus, the method comprising:
obtaining, through a bitstream, image information including a motion information candidate index and residual information;
constructing a motion information candidate list based on a neighboring block of a current block;
deriving motion information of the current block based on a motion information candidate indicated by the motion information candidate index among motion information candidates of the motion information candidate list;
deriving a prediction sample of the current block based on the motion information;
deriving a current residual coefficient based on residual syntax elements for the current residual coefficient in the current block;
deriving a residual sample based on the current residual coefficient; and
deriving a reconstructed sample of the current block based on the prediction sample and the residual sample,
wherein the residual information includes the residual syntax elements for the current residual coefficient,
wherein a number of context-coded residual syntax elements for residual coefficients prior to the current residual coefficient among residual coefficients of the current block is equal to a maximum number of context coded bins of the current block,
wherein the residual syntax elements for the current residual coefficient include coefficient level information for the current residual coefficient and a sign flag of the current residual coefficient,
wherein an absolute level of the current residual coefficient is derived as a value indicated by the coefficient level information for the current residual coefficient, and a sign of the current residual coefficient is derived as a sign indicated by the sign flag,
wherein the current residual coefficient is derived without performing level mapping,
wherein a first residual coefficient is derived by performing the level mapping, and the first residual coefficient is one of the residual coefficients prior to the current residual coefficient, and
wherein an absolute level of the first residual coefficient is derived based on residual syntax elements for the first residual coefficient, a maximum value among an absolute level of a left residual coefficient of the first residual coefficient and an absolute level of a top residual coefficient of the residual coefficient is derived, and a modified absolute level of the first residual coefficient is derived by comparing the absolute level of the first residual coefficient with the maximum value.
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