Method and apparatus for generating residual signals using reference between components
The present disclosure is related to a method and an apparatus for generating residual signals using reference between components. The video encoding/decoding apparatus and method derive residual signals of a chroma component of a current block. In deriving the residual signals of the chroma component, the video encoding/decoding apparatus and method use the residual signals of a previously reconstructed block without transmitting residual signals of part of the chroma component of the current block.
1 . A method for reconstructing a chroma residual block of a current block performed by a video decoding apparatus, the method comprising:
determining that a first chroma residual block of a current block for a first chroma component is not transmitted in a bitstream and the first chroma residual block is derived from a reference component residual block which is a previously decoded residual block of the current block for a reference color component, the reference color component being either a luma component or a second chroma component;
deriving positions of first neighboring residual samples of the first chroma residual block and second neighboring residual samples of the reference component residual block based on information representing a reference relationship between the first chroma residual block and the reference component residual block within the current block;
generating a linear relationship between the first neighboring residual samples and the second neighboring residual samples; and
reconstructing the first chroma residual block by applying the linear relationship to the reference component residual block without decoding residual signals for the first chroma residual block from the bitstream.
2 . The method of claim 1 , wherein deriving the positions comprises selecting the first neighboring residual samples and the second neighboring residual samples to maintain a one-to-one correspondence between the first neighboring residual samples and the second neighboring residual samples.
3 . The method of claim 1 , wherein, when the first chroma residual block and the reference component residual block have a same size, deriving the positions comprises:
selecting all or part of neighboring samples adjacent to the top or left of the first chroma residual block as the first neighboring residual samples, and
selecting all or part of neighboring samples adjacent to the top or left of the reference component residual block as the first second neighboring residual samples.
4 . The method of claim 1 , wherein, when a size of the first chroma residual block is smaller than a size of the reference component residual block, deriving the positions comprises:
selecting all n samples (where n is a natural number) adjacent to the top and left of the first chroma residual block as the first neighboring residual samples, and selecting n samples obtained by subsampling the top and left portion of the reference component residual block as the second neighboring residual samples.
5 . The method of claim 1 , wherein, when a width of the reference component residual block is α times a width of the first chroma residual block (where α is a natural number), deriving the positions comprises selecting the second neighboring residual samples obtained by sampling specific positions within each non-overlapping for each non-overlapping area with a size of α×line num (where line num is a natural number) in a top portion of the reference component residual block.
6 . The method of claim 1 , wherein, when a height of the reference component residual block is β times the height of the first chroma residual block (where β is a natural number), deriving the positions comprises selecting the second neighboring residual samples obtained by sampling specific positions within each non-overlapping area for each non-overlapping area with a size of β×line num in a left portion of the reference component residual block.
7 . The method of claim 1 , wherein, when a size of the reference component residual block is different from a size of the first chroma residual block, generating the first chroma residual block comprises downsampling the reference component residual block to make the reference component residual block and the first chroma residual block have a same size.
8 . A method for reconstructing a chroma residual block of a current block performed by a video encoding apparatus, the method comprising:
determining that a first chroma residual block of a current block for a first chroma component is not transmitted in a bitstream and the first chroma residual block is derived from a previously decoded residual block of the current block for a reference color component, the reference color component being either a luma component or a second chroma component;
generating information representing a reference relationship between the first chroma residual block and the reference component residual block within the current block;
deriving positions of first neighboring residual samples of the first chroma residual block and second neighboring residual samples of the reference component residual block based on the information representing the reference relationship;
generating a linear relationship between the first neighboring residual samples and the second neighboring residual samples; and
reconstructing the first chroma residual block by applying the linear relationship to the reference component residual block.
9 . The method of claim 8 , wherein deriving the positions comprises using a residual block of a luma component or a chroma component as the reference component residual block within the current block.
10 . The method of claim 8 , wherein deriving the positions comprises selecting the first neighboring residual samples and the second neighboring residual samples to maintain a one-to-one correspondence between the first neighboring residual samples and the second neighboring residual samples.
11 . A method for providing a video decoding apparatus with video data, wherein the method comprising:
encoding the video data into a bitstream; and
transmitting the bitstream to the video decoding device,
wherein encoding the video data includes:
determining that a first chroma residual block of a current block for a first chroma component is not transmitted in a bitstream and the first chroma residual block is derived from a previously decoded residual block of the current block for a reference color component, the reference color component being either a luma component or a second chroma component,
generating information representing a reference relationship between the first chroma residual block and the reference component residual block within a current block,
deriving positions of first neighboring residual samples of the first chroma residual block and second neighboring residual samples of the reference component residual block based on the information representing the reference relationship,
generating a linear relationship between the first neighboring residual samples and the second neighboring residual samples, and
reconstructing the first chroma residual block by applying the linear relationship to the reference component residual block.