US 12,149,712 B2
Video coding method on basis of transformation, and device therefor
Moonmo Koo, Seoul (KR); Seunghwan Kim, Seoul (KR); and Jaehyun Lim, Seoul (KR)
Assigned to LG ELECTRONICS INC., Seoul (KR)
Filed by LG ELECTRONICS INC., Seoul (KR)
Filed on Sep. 11, 2023, as Appl. No. 18/244,648.
Application 18/244,648 is a continuation of application No. 17/589,215, filed on Jan. 31, 2022, granted, now 11,805,263.
Application 17/589,215 is a continuation of application No. PCT/KR2020/010487, filed on Aug. 7, 2020.
Claims priority of provisional application 62/884,669, filed on Aug. 8, 2019.
Prior Publication US 2023/0421780 A1, Dec. 28, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. H04N 19/176 (2014.01); H04N 19/18 (2014.01)
CPC H04N 19/176 (2014.11) [H04N 19/18 (2014.11)] 7 Claims
OG exemplary drawing
 
1. An image decoding method performed by a decoding apparatus, comprising:
receiving a bitstream including residual information;
deriving transform coefficients for a current block based on the residual information; and
deriving residual samples for the current block based on the transform coefficients,
wherein deriving the transform coefficients comprises:
deriving a zero-out block related to a region in which a significant transform coefficient exists in the current block; and
deriving a position of a last significant coefficient based on last significant coefficient prefix information on the position of the last significant coefficient,
wherein it is determined, based on at least one of a multiple transform selection (MTS) enabled flag or a subblock transform (SBT) flag, whether a width of the zero-out block is set to a fixed value pre-defined in the decoding apparatus,
wherein the MTS enabled flag is signaled from a sequence parameter set (SPS) of the bitstream and indicates whether an MTS intra enabled flag and an MTS inter enabled flag are present in the SPS,
wherein the MTS intra enabled flag equal to 1 indicates that MTS index information could be present for an intra coding unit, and the MTS intra enabled flag equal to 0 indicates that the MTS index information is not present for the intra coding unit,
wherein the MTS inter enabled flag equal to 1 indicates that the MTS index information could be present for an inter coding unit, and the MTS inter enabled flag equal to 0 indicates that the MTS index information is not present for the inter coding unit,
wherein the MTS index information indicates which transform kernels are applied to the current block,
wherein the SBT flag indicates whether SBT is used for a coding block to which the current block belongs,
wherein in response to a case where the MTS enabled flag indicates that the MTS intra enabled flag and the MTS inter enabled flag are present in the SPS and the SBT flag indicates that the SBT is used for the coding block, the width of the zero-out block is set to the fixed value,
wherein in response to a case where the MTS enabled flag indicates that the MTS intra enabled flag and the MTS inter enabled flag are present in the SPS and the SBT flag indicates that the SBT is not used for the coding block, the width of the zero-out block is set to a value derived based on a width of the current block, and
wherein in response to a case where the MTS enabled flag indicates that the MTS intra enabled flag and the MTS inter enabled flag are not present in the SPS, the width of the zero-out block is set to the value derived based on the width of the current block.