| CPC H04N 19/124 (2014.11) [H04N 19/176 (2014.11); H04N 19/18 (2014.11); H04N 19/619 (2014.11); H04N 19/649 (2014.11)] | 42 Claims |
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1. An image decoding apparatus capable of decoding an image from a bitstream using a plurality of blocks including a first block of a P×Q (P and Q are integers) array of pixels and a second block of an N×M (N is an integer satisfying N<P, and M is an integer satisfying M<Q) array of pixels, the image decoding apparatus comprising:
a decoding unit configured to decode data corresponding to a first array of quantized transform coefficients and data corresponding to a second array of quantized transform coefficients from the bitstream, the first array of quantized transform coefficients corresponding to the first block, the second array of quantized transform coefficients corresponding to the second block;
an inverse quantization unit configured to derive a first array of transform coefficients from the first array of quantized transform coefficients by using a first quantization matrix of an N×M array of elements, and derive a second array of transform coefficients from the second array of quantized transform coefficients by using a second quantization matrix of an N×M array of elements, wherein the first array of transform coefficients represents frequency components, and wherein the second array of transform coefficients represents frequency components; 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 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 the first quantization matrix of the N×M array of elements is a quantization matrix including a part of elements of a third quantization matrix of an R×S array (R is an integer satisfying R≤N, and S is an integer satisfying S≤M) of elements, and not including the other elements of the third quantization matrix,
wherein the second quantization matrix of the N×M array of elements is a quantization matrix including all elements of a fourth quantization matrix of the R×S array of elements, and
wherein the third quantization matrix is different from the fourth quantization matrix.
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