Image signal encoding/decoding method and device therefor
An image decoding method, according to the present disclosure, comprises the steps of: parsing tile column number information indicating a value wherein 1 is subtracted from the number of tile columns included in the i-th slice; parsing tile row number information indicating a value wherein 1 is subtracted from the number of tile rows included in the i-th slice; and, if the tile column number information and the tile row number information are both 0, further parsing number information related to the number of slices in which height information in a tile including the i-th slice is clearly signaled.
1. A method of decoding a video, the method comprising:
decoding slice number information from a bitstream, the slice number information indicating a value subtracting 1 from a number of slices included in a current picture;
decoding width information of a first slice from the bitstream, the width information indicating a value subtracting 1 from a number of tile columns included in the first slice;
decoding first height information of the first slice from the bitstream, the first height information indicating a value subtracting 1 from a number of tile rows included in the first slice; and
determining whether to additionally decode explicit number information from the bitstream or not,
wherein the explicit number information represents a number of slices for which second height information is explicitly signaled,
wherein the second height information indicates a value subtracting 1 from a number of Coding Tree Unit (CTU) rows included in a slice,
wherein determination of whether to additionally decode the explicit number information or not is based on whether both the width information and the first height information are 0,
wherein when the explicit number information is 0, a height of the first slice is set to be same as a height of a first tile and the second height information is not decoded for the first slice, and
wherein when the explicit number information is greater than 0, the height of the first slice is determined to be equal to or less than the height of the first tile based on the second height information decoded for the first slice.
2. The method of claim 1 , wherein whether to decode the second height information for a second slice among a plurality of slices included in the first tile is determined by comparing an index of the second slice with the explicit number information.
3. The method of claim 2 , wherein when it is determined to decode the second height information for the second slice, a height of the second slice is derived based on the second height information decoded for the second slice, and
wherein when it is determined not to decode the second height information for the second slice, the height of the second slice is derived based on the second height information which is decoded lastly for another slice.
4. The method of claim 2 , wherein when the index of the second slice is less than the explicit number information, the second height information is decoded for the second slice, and wherein when the index of the second slice is equal to or greater than the explicit number information, the second height information is not decoded for the second slice.
5. The method of claim 1 , wherein after parsing the width information and the first height information for the first slice who has a first index, the width information and the first height information are further decoded for a second slice who has a second index,
wherein when the first tile is partitioned into the plurality of slices, the second index is greater than the first index by a number of the plurality of slices, and
wherein when the first tile is not partitioned into the plurality of slices, the second index is greater than the first index by 1.
6. A method of encoding a video, the method comprising:
encoding slice number information into a bitstream, the slice number information indicating a value subtracting 1 from a number of slices included in a current picture;
encoding width information of a first slice into the bitstream, the width information indicating a value subtracting 1 from a number of tile columns included in the first slice;
encoding first height information of the first slice into the bitstream, the first height information indicating a value subtracting 1 from a number of tile rows included in the first slice, wherein in response that a height of the first slice is equal to or less than a first tile, the first height information is encoded with a value of 0; and
determining whether to additionally encode explicit number information into the bitstream or not,
wherein the explicit number information represents a number of slices for which second height information is explicitly signaled,
wherein the second height information indicates a value subtracting 1 from a number of Coding Tree Unit (CTU) rows included in a slice,
wherein when both the width information and the first height information are 0, the explicit number information is additionally encoded into the bitstream,
wherein when at least one of the width information and the first height information is not 0, encoding the explicit number information is omitted,
wherein in response that the explicit number information is encoded with a value of 0, the first slice is set to be same as the first tile, and
wherein in response that the first slice is one of a plurality of slices generated by partitioning the first tile, the explicit number information is encoded with a value greater than 0.
7. The method of claim 6 , wherein when an index of a second slice is smaller than the explicit number information, the second height information is encoded for the second slice, and
wherein when the index of the second slice is equal to or greater than the explicit number information, the second height information is not encoded for the second slice.
8. The method of claim 7 , wherein in response that the second height information is not encoded for the second slice, a height of the second slice has a height of a minimum among a height of another slice which the second height information is lastly encoded and a remaining height excluding a region occupied by previous slices in the first tile.
9. A non-transitory computer-readable medium for storing data associated with a video, comprising:
a data stream stored in the non-transitory computer-readable medium, the data stream comprising:
slice number information indicating a value subtracting 1 from a number of slices included in a current picture;
width information of a first slice, the width information indicating a value subtracting 1 from a number of tile columns included in the first slice; and
first height information of the first slice, the first height information indicating a value subtracting 1 from a number of tile rows included in the first slice,
wherein, based on whether both the width information and the first height information are 0, it is determined whether the data stream additionally comprises explicit number information or not,
wherein the explicit number information represents a number of slices for which second height information is explicitly signaled,
wherein the second height information indicates a value subtracting 1 from a number of Coding Tree Unit (CTU) rows included in a slice,
wherein when the explicit number information is 0, a height of the first slice is set to be same as a height of a first tile without referring to the second height information for the first slice, and
wherein when the explicit number information is greater than 0, the height of the first slice is determined to be equal to or less than the height of the first tile based on the second height information for the first slice.