US 12,137,224 B2
Image encoding apparatus, image decoding apparatus, methods for the same, and non-transitory computer-readable storage medium for suppressing the code amount of quantization matrices
Masato Shima, Tokyo (JP)
Assigned to Canon Kabushiki Kaisha, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Mar. 15, 2022, as Appl. No. 17/695,638.
Application 17/695,638 is a continuation of application No. PCT/JP2020/030904, filed on Aug. 14, 2020.
Claims priority of application No. 2019-170810 (JP), filed on Sep. 19, 2019.
Prior Publication US 2022/0210421 A1, Jun. 30, 2022
Int. Cl. H04N 19/126 (2014.01); H04N 19/176 (2014.01); H04N 19/18 (2014.01); H04N 19/186 (2014.01)
CPC H04N 19/126 (2014.11) [H04N 19/176 (2014.11); H04N 19/18 (2014.11); H04N 19/186 (2014.11)] 11 Claims
OG exemplary drawing
 
1. An image encoding apparatus comprising:
a quantization unit configured to quantize transform coefficients in a block in an image, using a first quantization matrix; and
an encoding unit configured to encode the first quantization matrix,
wherein
(a) in a case where a first mode is used to encode the first quantization matrix, the encoding unit encodes, into a scaling list data syntax structure, information indicating that the first quantization matrix is the same as a second quantization matrix to be referenced, and encodes, into the scaling list data syntax structure, information for specifying the second quantization matrix,
(b) in a case where a second mode is used to encode the first quantization matrix, the encoding unit encodes, into the scaling list data syntax structure, the information for specifying the second quantization matrix, and encodes, into the scaling list data syntax structure, information for deriving a difference between an element of the first quantization matrix and an element of the second quantization matrix, and
(c) in a case where a third mode is used to encode the first quantization matrix, the encoding unit encodes a difference between an element and another element within the first quantization matrix,
wherein a code amount of information representing that the first mode is used is less than a code amount of information representing that the second mode is used,
wherein the code amount of information representing that the first mode is used is not greater than a code amount of information representing that the third mode is used, and
wherein a size of the second quantization matrix can only be 2×2, 4×4, or 8×8.