Image coding method based on information related to tile and information related to slice in video or image coding system
According to a disclosure of the present document, information/parameter related to splitting of a picture can be signaled on the basis of a no-picture partition flag, information related to a tile, and information related to a slice, unnecessary redundant signaling can be removed accordingly, and the number of bits assigned to the signaling can be reduced, thereby deriving an effect of increasing an overall coding efficiency.
1. An image decoding method performed by a decoding device, the method comprising:
obtaining image information through a bitstream, wherein the image information includes a no-picture partition flag related to no-picture partitioning, and wherein based on a value of the no-picture partition flag being 0, the image information further includes information related to tile and information related to slice;
deriving at least one tile in a current picture based on the information related to tile;
deriving at least one slice in the current picture based on the information related to slice; and
decoding the current picture based on the at least one tile and the at least one slice,
wherein the information related to slice includes a rectangular slice flag, and the rectangular slice flag is related to whether tiles within a slice cover a rectangular region of the current picture,
wherein based on the value of the no-picture partition flag being 0, a number of the at least one tile being derived as 1 and a value of the rectangular slice flag being 1, a number of the at least one slice is limited to be greater than 1.
2. The method of claim 1 ,
wherein based on the number of the at least one tile being derived as a value greater than 1, the information related to slice includes information on a number of slices and a tile index delta present flag,
wherein a value of the information on the number of slices plus 1 is related to a number of rectangular slices in the current picture, and
wherein the tile index delta present flag is related to whether a difference value between tile indexes containing a first CTU (Coding Tree Unit) of two slices is signaled.
3. The method of claim 2 ,
wherein based on the value of the no-picture partition flag being 0, the number of the at least one tile being derived as 1 and the information on the number of slices not being present, a value of the information on the number of slices is derived as 1.
4. The method of claim 2 ,
wherein based on the value of the no-picture partition flag being 0, the number of the at least one tile being derived as 1, and the tile index delta present flag not being present, a value of the tile index delta present flag is derived as 0.
5. The method of claim 2 ,
wherein the number of the at least one slice minus 1 is set equal to the value of the number information of the slices.
6. The method of claim 1 , further including a step of deriving a number of slices in tile containing a 0-th slice in the current picture,
wherein based on the value of the no-picture partition flag being 0, a number of the at least one tile being derived as 1 and a value of the rectangular slice flag being 1, the number of the at least one slice minus 1 is set equal to the number of slices in tile containing the 0-th slice in the current picture.
7. The method of claim 1 ,
wherein the information related to tile includes a single tile per picture flag related to whether the current picture consists of a single tile, and
wherein based on a value of the single tile per picture flag being 1, the information related to tile further includes information on a number of slices in the single tile and height information of each of the slices in the single tile.
8. The method of claim 1 ,
wherein the information related to slice includes information on a number of slices in tile related to a number of rectangular slices in tile for each of the at least one tile,
wherein based on a number of slices in tile derived by the information on the number of slices in tile being greater than 1, the information related to slice further includes slice height information for each of the rectangular slices in tile,
wherein based on the number of slices in tile derived by the information on the number of slices in tile being 1, the information related to slice further includes a single slice per tile flag and slice map index information, and
wherein the single tile per slice flag is related to whether a single tile is present in a slice, and the slice map index information is related to an index of tile to slice.
9. The method of claim 8 ,
based on a value of the single slice per tile flag being 0, the information related to slice includes the slice map index information.
10. The method of claim 1 ,
wherein the information related to tile includes information on a number of tile columns related to a unique number of widths of consecutive tile columns, and a column frequency information present flag related to whether or not a column frequency information is signaled,
wherein the column frequency information is related to a frequency of a width of each tile columns based on the unique number of the widths of consecutive tile columns, and
wherein based on a value of the column frequency information present flag being 1, the information related to tile further includes the column frequency information.
11. The method of claim 1 ,
wherein the information related to tile includes information on a number of tile rows related to a unique number of heights of consecutive tile rows, and a row frequency information present flag related to whether or not a row frequency information is signaled,
wherein the row frequency information is related to a frequency of a height of each tile rows based on the unique number of the widths of consecutive tile rows, and
wherein based on a value of the row frequency information present flag being 1, the information related to tile further includes the row frequency information.
12. An image encoding method performed by an encoding device, the method comprising:
deriving at least one tile and at least one slice in a current picture;
generating information related to tile, information related to slice and a no-picture partition flag related to no-picture partitioning based on the at least one tile and the at least one slice; and
encoding image information including the information related to tile, the information related to slice and the no-picture partition flag,
wherein the information related to slice includes a rectangular slice flag, and the rectangular slice flag is related to whether tiles within a slice cover a rectangular region of the current picture,
wherein based on a value of the no-picture partition flag being 0, a number of the at least one tile being derived as 1, and a value of the rectangular slice flag being 1, a number of the at least one slice is limited to be greater than 1.
13. The method of claim 12 ,
wherein based on the number of the at least one tile being derived as a value greater than 1, the information related to slice includes information on a number of slices and a tile index delta present flag,
wherein a value of the information on the number of slices plus 1 is related to a number of rectangular slices in the current picture, and
wherein the tile index delta present flag is related to whether a difference value between tile indexes containing a first CTU (Coding Tree Unit) of two slices is signaled.
14. The method of claim 13 ,
wherein based on the value of the no-picture partition flag being 0, the number of the at least one tile being derived as 1 and the tile index delta present flag not being present, a value of the tile index delta present flag is derived as 0.
15. A computer-readable digital storage medium for storing a bitstream generated by an image encoding method, the image encoding method comprising:
deriving at least one tile and at least one slice in a current picture;
generating information related to tile, information related to slice and a no-picture partition flag related to no-picture partitioning based on the at least one tile and the at least one slice; and
encoding image information including the information related to tile, the information related to slice and the no-picture partition flag,
wherein the information related to slice includes a rectangular slice flag, and the rectangular slice flag is related to whether tiles within a slice cover a rectangular region of the current picture,
wherein based on a value of the no-picture partition flag being 0, a number of the at least one tile being derived as 1 and a value of the rectangular slice flag being 1, a number of the at least one slice is limited to be greater than 1.