Video encoding/decoding method and device using segmentation limitation for chroma block, and method for transmitting bitstream

1 . An image decoding method performed by an image decoding apparatus, the image decoding method comprising:

obtaining information on splitting of a current block from a bitstream;

splitting the current block based on the information on splitting of the current block;

decoding the current block; and

wherein the information on splitting of the current block comprises at least one of a splitting direction or a splitting type,

wherein, based on the current block being a chroma block, a tree structure of the current chroma block being a dual tree structure and a width of the current block being equal to 8, vertical ternary splitting is not allowed for the current block regardless of a height of block(s) being derived from the current block by the vertical ternary splitting.

2 . The image decoding method of claim 1 ,

wherein, based on the current block being a chroma block and the width of the current block being equal to 4, vertical binary splitting is not allowed for the current block.

3 . The image decoding method of claim 1 , wherein, based on predetermined splitting being not allowed for the current block, the information on splitting of the current block is determined as a value specifying splitting other than the predetermined splitting.

4 . The image decoding method of claim 3 ,

wherein the information on splitting of the current block includes splitting type information specifying ternary splitting or binary splitting,

wherein, based on vertical ternary splitting and horizontal ternary splitting being not allowed for the current block, the splitting type information is determined as a value specifying binary splitting, and

wherein, based on vertical binary splitting and horizontal binary splitting being not allowed for the current block, the splitting type information is determined as a value specifying ternary splitting.

5 . The image decoding method of claim 3 ,

wherein the information on splitting of the current block includes splitting direction information specifying vertical splitting or horizontal splitting,

wherein, based on vertical binary splitting and vertical ternary splitting being not allowed for the current block and horizontal binary splitting or horizontal ternary splitting are allowed, the splitting direction information is determined as a value specifying horizontal splitting, and

wherein, based on horizontal binary splitting and horizontal ternary splitting being not allowed for the current block and vertical binary splitting or vertical ternary splitting are allowed, the splitting direction information is determined as a value specifying vertical splitting.

6 . The image decoding method of claim 1 , further comprising:

based on the current block being a chroma block predicted in an IBC (intra block copy) mode,

splitting a luma block corresponding to the current block into luma subblocks each having a predetermined size;

obtaining motion information of the luma subblocks;

deriving motion information of subblocks in the current block corresponding to the luma subblocks based on the motion information of the luma subblocks; and

performing IBC prediction on the current block based on the derived motion information,

wherein the predetermined size of each of the luma subblocks is 8×8.

7 . An image encoding method performed by an image encoding apparatus, the image encoding method comprising:

splitting a current block based on whether predetermined splitting is allowed for the current block;

encoding information on splitting of the current block; and

encoding the current block,

wherein the information on splitting of the current block comprises at least one of a splitting direction or a splitting type,

wherein, based on the current block being a chroma block, a tree structure of the current chroma block being a dual tree structure and a width of the current block being equal to 8, vertical ternary splitting is not allowed for the current block regardless of a height of block(s) being derived from the current block by the vertical ternary splitting.

8 . The image encoding method of claim 7 ,

wherein, based on the current block being a chroma block and the width of the current block being equal to 4, vertical binary splitting is not allowed for the current block.

9 . A method of transmitting a bitstream comprising:

transmitting a bitstream generated by an image encoding method;

wherein the image encoding method comprises,

splitting a current block based on whether predetermined splitting is allowed for the current block;

encoding information on splitting of the current block into the bitstream; and

encoding the current block into the bitstream,

wherein the information on splitting of the current block comprises at least one of a splitting direction or a splitting type,

wherein, based on the current block being a chroma block, a tree structure of the current chroma block being a dual tree structure and a width of the current block being equal to 8, vertical ternary splitting is not allowed for the current block regardless of a height of block(s) being derived from the current block by the vertical ternary splitting.

10 . An image decoding apparatus comprising:

at least one processor; and

at least one memory including program code, the at least one memory and the program code configured to, with the at least one processor cause the apparatus at least to perform:

obtaining information on splitting of a current block from a bitstream;

splitting the current block based on the information on splitting of the current block;

decoding the current block; and

wherein the information on splitting of the current block comprises at least one of a splitting direction or a splitting type,

wherein, based on the current block being a chroma block, a tree structure of the current chroma block being a dual tree structure and a width of the current block being equal to 8, vertical ternary splitting is not allowed for the current block regardless of a height of block(s) being derived from the current block by the vertical ternary splitting.

11 . An image encoding apparatus comprising:

at least one processor; and

at least one memory including program code, the at least one memory and the program code configured to, with the at least one processor cause the apparatus at least to perform:

splitting a current block based on whether predetermined splitting is allowed for the current block;

encoding information on splitting of the current block; and

encoding the current block,

wherein the information on splitting of the current block comprises at least one of a splitting direction or a splitting type,

wherein, based on the current block being a chroma block, a tree structure of the current chroma block being a dual tree structure and a width of the current block being equal to 8, vertical ternary splitting is not allowed for the current block regardless of a height of block(s) being derived from the current block by the vertical ternary splitting.

12 . An apparatus comprising:

at least one processor; and

at least one memory including program code, the at least one memory and the program code configured to, with the at least one processor cause the apparatus at least to perform:

transmitting a bitstream generated by an image encoding method;

wherein the image encoding method comprises,

splitting a current block based on whether predetermined splitting is allowed for the current block;

encoding information on splitting of the current block into the bitstream; and

encoding the current block into the bitstream,

wherein the information on splitting of the current block comprises at least one of a splitting direction or a splitting type,

wherein, based on the current block being a chroma block, a tree structure of the current chroma block being a dual tree structure and a width of the current block being equal to 8, vertical ternary splitting is not allowed for the current block regardless of a height of block(s) being derived from the current block by the vertical ternary splitting.