Method and apparatus for processing image signal
Embodiments of the disclosure provide a method and apparatus for processing video signals. An image signal decoding method according to an embodiment of the disclosure comprises the steps of: determining, on the basis of the height and width of a current block, an input length and output length of a non-separable transform; determining a non-separable transform matrix corresponding to the input length and output length of the non-separable transform; and applying the non-separable transform matrix to the current block, wherein, when the height and width of the current block are 4 each, the input length and output length of the non-separable transform are determined to be 8 and 16 respectively.
1. A method for decoding an image signal, comprising:
determining an input length and an output length of a non-separable transform based on a height and a width of a current block;
determining a non-separable transform matrix related to the input length and the output length of a non-separable transform; and
applying the non-separable transform matrix to coefficients by a number of the input length in the current block,
wherein the input length of the non-separable transform is determined as 8, and the output length of the non-separable transform is determined as 16, based on that each of the height and the width of a current block is equal to 4.
2. The method of claim 1 ,
wherein the input length and the output length of the non-separable transform is determined as 16, based on that each of the height and the width of a current block is not equal to 8.
3. The method of claim 2 ,
wherein applying the non-separable transform matrix comprises applying the non-separable transform matrix to a top-left 4×4 region of the current block based on that each of the height and the width of a current block is not equal to 4 and a multiplication of the width and the height is less than a threshold value.
4. The method of claim 2 ,
wherein applying the non-separable transform matrix comprises applying the non-separable transform matrix to a top-left 4×4 region of the current block and a 4×4 region located at a right side of the top-left 4×4 region, based on that each of the height and the width of a current block is not equal to 4 and the width is greater than or equal to the height.
5. The method of claim 2 ,
wherein applying the non-separable transform matrix comprises applying the non-separable transform matrix to a top-left 4×4 region of the current block and a 4×4 region located at a bottom side of the top-left 4×4 region, based on that each of the height and the width of a current block is not equal to 4, a multiplication of the width and the height is greater than or equal to the threshold value, and the width is less than the height.
6. The method of claim 1 ,
wherein determining the non-separable transform matrix comprises:
determining a non-separable transform set index based on an intra prediction mode of the current block;
determining a non-separable transform kernel related to a non-separable transform index in non-separable transform set included in the non-separable transform set index; and
determining the non-separable transform matrix from the non-separable transform based on the input length and the output length.
7. An apparatus for decoding an image signal, comprising:
a memory configured to store the image signal; and
a processor coupled to the memory,
wherein the processor is configured to:
determine an input length and an output length of a non-separable transform based on a height and a width of a current block;
determine a non-separable transform matrix related to the input length and the output length of a non-separable transform; and
apply the non-separable transform matrix to coefficients by a number of the input length in the current block,
wherein the input length of the non-separable transform is determined as 8, and the output length of the non-separable transform is determined as 16, based on that each of the height and the width of a current block is equal to 4.
8. The apparatus of claim 7 ,
wherein the input length and the output length of the non-separable transform is determined as 16, based on that each of the height and the width of a current block is not equal to 8.
9. The apparatus of claim 8 ,
wherein the processor is configured to apply the non-separable transform matrix to a top-left 4×4 region of the current block based on that each of the height and the width of a current block is not equal to 4 and a multiplication of the width and the height is less than a threshold value.
10. The apparatus of claim 8 ,
wherein the processor is configured to apply the non-separable transform matrix to a top-left 4×4 region of the current block and a 4×4 region located at a right side of the top-left 4×4 region, based on that each of the height and the width of a current block is not equal to 4 and the width is greater than or equal to the height.
11. The apparatus of claim 8 ,
wherein the processor is configured to apply the non-separable transform matrix to a top-left 4×4 region of the current block and a 4×4 region located at a bottom side of the top-left 4×4 region, based on that each of the height and the width of a current block is not equal to 4, a multiplication of the width and the height is greater than or equal to the threshold value, and the width is less than the height.
12. The apparatus of claim 7 ,
wherein the processor is configured to:
determine a non-separable transform set index based on an intra prediction mode of the current block;
determine a non-separable transform kernel related to a non-separable transform index in non-separable transform set included in the non-separable transform set index; and
determine the non-separable transform matrix from the non-separable transform based on the input length and the output length.