US 11,706,419 B2
Conversion factor level coding method and device therefor
Jungah Choi, Seoul (KR); Seunghwan Kim, Seoul (KR); Sunmi Yoo, Seoul (KR); Jangwon Choi, Seoul (KR); and Jin Heo, Seoul (KR)
Assigned to LG ELECTRONICS, INC., Seoul (KR)
Filed by LG ELECTRONICS INC., Seoul (KR)
Filed on Sep. 15, 2022, as Appl. No. 17/945,786.
Application 17/945,786 is a continuation of application No. 17/365,559, filed on Jul. 1, 2021, granted, now 11,490,088.
Application 17/365,559 is a continuation of application No. 16/856,406, filed on Apr. 23, 2020, granted, now 11,095,897, issued on Aug. 17, 2021.
Application 16/856,406 is a continuation of application No. PCT/KR2019/012226, filed on Sep. 20, 2019.
Claims priority of provisional application 62/734,233, filed on Sep. 20, 2018.
Claims priority of provisional application 62/734,266, filed on Sep. 21, 2018.
Prior Publication US 2023/0023002 A1, Jan. 26, 2023
Int. Cl. H04N 19/132 (2014.01); H04N 19/129 (2014.01); H04N 19/176 (2014.01); H04N 19/46 (2014.01)
CPC H04N 19/132 (2014.11) [H04N 19/129 (2014.11); H04N 19/176 (2014.11); H04N 19/46 (2014.11)] 11 Claims
OG exemplary drawing
 
1. An image decoding method performed by a decoding apparatus, the method comprising:
receiving a bitstream comprising residual information;
deriving quantized transform coefficients for a current block based on the residual information comprised in the bitstream;
deriving residual samples for the current block based on the quantized transform coefficients; and
generating a reconstructed picture based on the residual samples for the current block,
wherein the residual information comprises a significant coefficient flag, a parity level flag, a first transform coefficient level flag, a second transform coefficient level flag, an abs remainder syntax element, and a sign flag for a quantized transform coefficient for the current block, wherein the significant coefficient flag is related to whether the quantized transform coefficient is a non-zero significant coefficient, the parity level flag is for a parity of a transform coefficient level for the quantized transform coefficient, the first transform coefficient level flag is about whether the transform coefficient level is larger than a first threshold, the second transform coefficient level flag is about whether the transform coefficient level is larger than a second threshold, the abs_remainder syntax element is about a remaining value of the transform coefficient level, the sign flag is about a sign of the quantized transform coefficient,
wherein the first threshold is 1 and the second threshold is 3,
wherein the deriving of the quantized transform coefficients comprises determining a threshold related to a sum of a number of significant coefficient flags for the transform coefficients within the current block, a number of first transform coefficient level flags, a number of parity level flags, and a number of second transform coefficient level flags based on a size of the current block;
decoding the significant coefficient flag, the first transform coefficient level flag, the parity level flag, the second transform coefficient level flag, the abs_remainder syntax element and the sign flag; and
deriving the quantized transform coefficient based on a value of the decoded significant coefficient flag, a value of the decoded parity level flag, a value of the decoded first transform coefficient level flag, a value of the decoded second transform coefficient level flag, a value of the decoded abs remainder syntax element and a value of the decoded sign flag, and
wherein the decoding of the first transform coefficient level flag is performed prior to the decoding of the parity level flag,
wherein based on the transform coefficient level of the quantized transform coefficient being 1, the parity level flag and the second transform coefficient level flag are not decoded, and
wherein the sum of the number of significant coefficient flags for the quantized transform coefficients within the current block, the number of first transform coefficient level flags, the number of parity level flags, and the number of second transform coefficient level flags, which are comprised in the residual information, is the threshold or less.