CPC H04N 19/52 (2014.11) [H04N 19/105 (2014.11); H04N 19/132 (2014.11); H04N 19/167 (2014.11); H04N 19/176 (2014.11)] | 3 Claims |
1. An image decoding method performed by a decoding apparatus, the method comprising:
deriving a position of a current subblock within a current block based on a center sample position of the current subblock;
deriving a reference subblock on a collocated reference picture based on the position of the current subblock;
deriving a subblock temporal motion vector predictor (sbTMVP) candidate based on a motion vector of the reference subblock;
deriving a motion vector of the current subblock based on the sbTMVP candidate;
generating prediction samples of the current block based on the motion vector of the current subblock;
generating residual samples of the current block based on residual information obtained from a bitstream; and
generating reconstruction samples based on the prediction samples and the residual samples,
wherein the center sample position represents a position of a right-lower center sample positioned at a bottom right, among four samples positioned at the center,
wherein for the reference subblock that is available, a motion vector of the available reference subblock is derived as the sbTMVP candidate,
wherein the motion vector of the available reference subblock is derived based on a motion vector of a block covering a modified location derived based on a top-left sample position of the reference subblock, and
wherein the modified location is derived by an equation ((xColSb>>3)<<3, (yColSb>>3)<<3), where the xColSb and the yColSb represent the x coordinate and y coordinate of the sample position of the reference subblock derived based on the center sample position of the current subblock, respectively, and >> represents an arithmetic right shift, and << represents an arithmetic left shift.
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