Method for processing video signal by using transform, and apparatus therefor
A method for processing a video includes determining a horizontal transform type index for a horizontal transform kernel and a vertical transform type index for a vertical transform kernel of a transform block in the video signal, determining a transform region in which a significant transform coefficient exists in the transform block based on the horizontal transform type index, the vertical transform type index, and a size of the transform block, and applying inverse-transform to the transform region based on the horizontal transform type index and the vertical transform type index. A width of the transform region is determined based on a comparison between the horizontal transform type index and a reference value and a height of the transform region is determined based on a comparison between the vertical transform type index and the reference value.
1. A method for decoding image information, the method comprising:
determining a horizontal transform type index for a horizontal transform kernel and a vertical transform type index for a vertical transform kernel of a transform block in the image information;
determining a transform region in which a significant transform coefficient exists in the transform block based on the horizontal transform type index, the vertical transform type index, and a width and a height of the transform block; and
applying, using a transformation matrix, inverse-transform to the transform region based on the horizontal transform type index and the vertical transform type index,
wherein the transformation matrix is derived as a transformation matrix, which has 32 columns and 16 rows, based on at least one of (i) the horizontal transform type index being greater than 0 and the width of the transform block being 32 or (ii) the vertical transform type index being greater than 0 and the height of the transform block being 32.
2. A method for encoding image information, the method comprising:
determining transform kernels to be applied to horizontal and vertical directions of a current block including a residual signal except a predicted signal in the image information, the transform kernels including a horizontal transform kernel and a vertical transform kernel;
generating transform information about the transform kernels, the transform information including a horizontal transform type index for the horizontal transform kernel and a vertical transform type index for the vertical transform kernel;
generating residual information for a transformed block by respectively applying horizontal transform and vertical transform to the horizontal direction and the vertical direction of the current block based on the transform kernels related to the transform information; and
encoding the image information including the transform information and the residual information,
wherein a width and a height of the transformed block is determined based on the horizontal transform type index, the vertical transform type index, and a width and a height of the transform block,
wherein coefficients existing in a region other than a region in which the transformed block is generated in the current block are regarded as 0, and
wherein a transformation matrix, which has 32 columns and 16 rows, for at least one of the horizontal transform or the vertical transform is derived based on at least one of (i) the horizontal transform type index being greater than 0 and the width of the transform block being 32 or (ii) the vertical transform type index being greater than 0 and the height of the transform block being 32.
3. A method for transmitting image information, the method comprising:
generating a bitstream for the image information, the image information generated by determining transform kernels to be applied to horizontal and vertical directions of a current block including a residual signal except a predicted signal in the image information, the transform kernels including a horizontal transform kernel and a vertical transform kernel, generating transform information about the transform kernels, the transform information including a horizontal transform type index for the horizontal transform kernel and a vertical transform type index for the vertical transform kernel, generating residual information for a transformed block by respectively applying horizontal transform and vertical transform to the horizontal direction and the vertical direction of the current block based on the transform kernels related to the transform information, and encoding the image information including the transform information and the residual information; and
transmitting the image information comprising the bitstream,
wherein a width and a height of the transformed block is determined based on the horizontal transform type index, the vertical transform type index, and a width and a height of the transform block,
wherein coefficients existing in a region other than a region in which the transformed block is generated in the current block are regarded as 0, and
wherein a transformation matrix, which has 32 columns and 16 rows, for at least one of the horizontal transform or the vertical transform is derived based on at least one of (i) the horizontal transform type index being greater than 0 and the width of the transform block being 32 or (ii) the vertical transform type index being greater than 0 and the height of the transform block being 32.