US 12,407,859 B2
Method for processing image on basis of transform and device therefor
Moonmo Koo, Seoul (KR); Jaehyun Lim, Seoul (KR); and Seunghwan Kim, Seoul (KR)
Assigned to LG Electronics Inc., Seoul (KR)
Appl. No. 17/430,496
Filed by LG ELECTRONICS INC., Seoul (KR)
PCT Filed Feb. 12, 2020, PCT No. PCT/KR2020/001986
§ 371(c)(1), (2) Date Aug. 12, 2021,
PCT Pub. No. WO2020/166977, PCT Pub. Date Aug. 20, 2020.
Claims priority of provisional application 62/804,752, filed on Feb. 12, 2019.
Prior Publication US 2022/0086490 A1, Mar. 17, 2022
Int. Cl. H04N 19/61 (2014.01); H04N 19/176 (2014.01); H04N 19/46 (2014.01); H04N 19/625 (2014.01); H04N 19/70 (2014.01)
CPC H04N 19/61 (2014.11) [H04N 19/176 (2014.11); H04N 19/46 (2014.11); H04N 19/625 (2014.11); H04N 19/70 (2014.11)] 3 Claims
OG exemplary drawing
 
1. A method for decoding a video signal, comprising:
obtaining a sub-block transform (SBT) flag indicating whether a SBT is applied, wherein the SBT represents a transform applied to a transform unit corresponding to one of subblocks split from a coding unit;
checking whether a condition related to a width and a height of the transform unit is satisfied;
determining a width variable and a height variable related to a transform target region based on the SBT flag and the condition; and
performing an inverse-transform on the transform target region based on the width variable and the height variable related to the transform target region,
wherein, based on the SBT flag indicating that the SBT is applied to the transform unit and the condition being satisfied, the width variable related to the transform target region is determined as a first reference value,
wherein, based on the SBT flag indicating that the SBT is not applied to the transform unit or the condition not being satisfied, the width variable related to the transform target region is determined as a smaller value among the width of the transform unit and a second reference value,
wherein, based on the SBT flag indicating that the SBT is applied to the transform unit and the condition being satisfied, the height variable related to the transform target region is determined as the first reference value,
wherein, based on the SBT flag indicating that the SBT is not applied to the transform unit or the condition not being satisfied, the height variable related to the transform target region is determined as a smaller value among the height of the transform unit and the second reference value,
wherein the inverse-transform on the transform target region comprises a horizontal direction transform and a vertical direction transform on a non-zero region in the transform unit,
wherein a horizontal transform kernel index indicating a type of a horizontal transform kernel for the horizontal direction transform is derived based on the SBT flag,
wherein a vertical transform kernel index indicating a type of a vertical transform kernel for the vertical direction transform is derived based on the SBT flag,
wherein a width of the non-zero region is determined as a smaller value among the width of the transform unit and 16, based on the horizontal transform kernel index being greater than zero, and
wherein a height of the non-zero region is determined as a smaller value among the height of the transform unit and 16, based on the vertical transform kernel index being greater than zero.