Patent ID: 11949867
Assignee: CANON KABUSHIKI KAISHA
Field: nan (nan)
Classification: CPC nan | IPC H

Claim 16:
17. A non-transitory computer-readable storage medium which stores a program for executing an image decoding method for decoding an image from encoded data, the method comprising:
decoding data for a quantization matrix used for inverse quantizing processing which derives transform coefficients from quantized transform coefficients;
deriving a plurality of values corresponding to at least a part of elements in the quantization matrix by using the data, and deriving the quantization matrix based on the plurality of values; and
performing the inverse quantizing processing on an object block using the quantization matrix,
wherein, in a case where a width of the object block is 16 samples and a height of the object block is 8 samples, the quantization matrix is derived in the deriving by:
setting a first value among the plurality of values as a first element corresponding to DC component in the quantization matrix, wherein the first value is not set for a plurality of elements in the quantization matrix used for the inverse quantizing processing, and the first value is derived by using difference from a predetermined initial value;
setting a second value among the plurality of values as a second element adjacent to the first element on a right side of the first element, wherein the second value is not set for a plurality of elements in the quantization matrix used for the inverse quantizing processing, and the second value is derived by using difference from the first value; and
setting a third value among the plurality of values as a third element and a fourth element, wherein the third element is below the first element and the fourth element is below the second element, wherein the third element is adjacent to the first element and the fourth element is adjacent to the second element, and wherein the third value is derived by using difference from the second value.