CPC H04N 19/11 (2014.11) [H04N 19/176 (2014.11); H04N 19/61 (2014.11)] | 4 Claims |
1. An image decoding method performed by a decoding apparatus, comprising:
obtaining image information comprising prediction related information from a bitstream;
deriving an intra prediction mode of a current block based on the prediction related information;
determining a modified intra prediction mode of the current block having a different width and height from the intra prediction mode, based on a ratio between the width and height of the current block and the intra prediction mode;
determining an inverse non-separable transform set based on the modified intra prediction mode; and
applying an inverse non-separable transform matrix selected from the inverse non-separable transform set, to a top-left region of the current block determined based on the width and height of the current block,
wherein the modified intra prediction mode is determined by adding 65 or −67 to the intra prediction mode,
wherein the determining of the inverse non-separable transform set comprises determining an index of the inverse non-separable transform set related to the modified intra prediction mode,
wherein based on that the modified intra prediction mode is greater than or equal to 0 and smaller than or equal to 1, the index is determined as a first index value,
wherein based on that the modified intra prediction mode is greater than or equal to 2 and smaller than or equal to 12, the index is determined as a second index value,
wherein based on that the modified intra prediction mode is greater than or equal to 13 and smaller than or equal to 23, the index is determined as a third index value,
wherein based on that the modified intra prediction mode is greater than or equal to 24 and smaller than or equal to 44, the index is determined as a fourth index value,
wherein based on that the modified intra prediction mode is greater than or equal to 45 and smaller than or equal to 55, the index is determined as the third index value,
wherein based on that the modified intra prediction mode is greater than or equal to 56, the index is determined as the second index value, and
wherein based on that the modified intra prediction mode is smaller than 0, the index is determined as the second index value.
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