Patent ID: 11930178
Assignee: CANON KABUSHIKI KAISHA
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 2:
3. An image decoding apparatus for decoding an encoded image, comprising:
a generation unit configured to generate, from a first quantization matrix having a size of 8×8, a second quantization matrix having a size of 4×16 the size of 4×16 indicates a size of 4 in a horizontal direction and a size of 16 in a vertical direction), wherein the first quantization matrix has a r-th row and a r-th column (r is an integer which satisfies 0≤r≤7), and the second quantization matrix has a p-th row and a q-th column(p is an integer which satisfies 0≤p≤15, and q is an integer which satisfies 0≤q≤3); and
an inverse quantization unit configured to inversely quantize quantized transformation coefficients in a block having a size corresponding to the size of 4×16 using the second quantization matrix,
wherein the generation unit generates the second quantization matrix by decreasing elements of the first quantization matrix having the size of 8×8 in a horizontal direction without increasing elements of the first quantization matrix having the size of 8×8 in the horizontal direction when generating the second quantization matrix from the first quantization matrix so that all elements at a 1-th column, a 3-th column, a 5-th column, and a 7-th column of the first quantization matrix are removed, and by increasing elements of the first quantization matrix having the size of 8×8 in a vertical direction so that an element at an m-th row and a 2n-th column in the first quantization matrix is arranged as an element at a 2m-th row and an n-th column in the second quantization matrix and an element at a (2m+1)-th row and the n-th column in the second quantization matrix, wherein m and n are integers of 0 or more.