US 12,262,056 B2
Image decoding apparatus, image decoding method, and storage medium
Masato Shima, Tokyo (JP)
Assigned to Canon Kabushiki Kaisha, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Mar. 13, 2024, as Appl. No. 18/604,047.
Application 18/604,047 is a continuation of application No. 17/467,982, filed on Sep. 7, 2021, granted, now 11,962,806.
Application 17/467,982 is a continuation of application No. PCT/JP2020/008422, filed on Feb. 28, 2020.
Claims priority of application No. 2019-044274 (JP), filed on Mar. 11, 2019.
Prior Publication US 2024/0223810 A1, Jul. 4, 2024
Int. Cl. H04N 19/61 (2014.01); H04N 19/124 (2014.01); H04N 19/136 (2014.01); H04N 19/176 (2014.01); H04N 19/184 (2014.01)
CPC H04N 19/61 (2014.11) [H04N 19/124 (2014.11); H04N 19/136 (2014.11); H04N 19/176 (2014.11); H04N 19/184 (2014.11)] 11 Claims
OG exemplary drawing
 
1. An image decoding apparatus capable of decoding an image from a bitstream by using a plurality of blocks including a first block of a P×Q array of pixels, where P and Q are integers, and a second block of an N×M array of pixels, where N is an integer satisfying N<P, and M is an integer satisfying M<Q, the image decoding apparatus comprising:
a decoding unit configured to decode, from the bitstream, data corresponding to a first array of quantized transform coefficients corresponding to the first block and data corresponding to a second array of quantized transform coefficients corresponding to the second block;
an inverse quantization unit configured to derive a first array of transform coefficients representing frequency components from the first array of quantized transform coefficients by using a first quantization matrix of an N×M array of elements, and configured to derive a second array of transform coefficients representing frequency components from the second array of quantized transform coefficients by using a second quantization matrix of an N×M array of elements; and;
an inverse transform unit configured to derive a first array of prediction residuals corresponding to the first block by performing inverse transform processing on the first array of transform coefficients, and configured to derive a second array of prediction residuals corresponding to the second block by performing inverse transform processing on the second array of transform coefficients,
wherein, in a case where a target block to be decoded is the first block, the inverse transform unit is configured to derive an N×Q array of intermediate values by performing multiplication of the first array of transform coefficients, which is an N×M array, and a matrix of an M×Q array, and to derive a P×Q array of prediction residuals for the first block by performing multiplication of a matrix of a P×N array and the N×Q array of intermediate values,
wherein the first quantization matrix of an N×M array of elements includes a part of elements of a third quantization matrix of an R×S array of elements and does not include the other elements of the third quantization matrix, where R is an integer satisfying R≤N, and S is an integer satisfying S≤M,
wherein the second quantization matrix of an N×M array of elements includes all elements of a fourth quantization matrix of an R×S array of elements,
wherein the third quantization matrix is different from the fourth quantization matrix,
wherein the first quantization matrix, except for an element corresponding to a DC component, consists of the part of elements of the third quantization matrix and
wherein the second quantization matrix, except for an element corresponding to a DC component, consists of all elements of the fourth quantization matrix.