Filtering-based image coding device and method
According to embodiments of the present document, information for carrying out in-loop filtering across virtual boundaries can be efficiently signaled. For example, in-loop filtering can be carried out on the basis of signaling of information which is related to whether in-loop filtering across virtual boundaries is enabled or not.
1. An image decoding method performed by a decoding apparatus, comprising:
obtaining image information including residual information through a bitstream;
generating reconstructed samples of a current picture, based on the residual information; and
generating modified reconstructed samples, based on an in-loop filtering process for the reconstructed samples,
wherein the image information includes a sequence parameter set (SPS) and picture header information,
wherein the SPS includes an SPS virtual boundaries enabled flag,
wherein the SPS further includes an SPS virtual boundaries present flag based on a value of the SPS virtual boundaries enabled flag,
wherein whether the in-loop filtering process is performed across the virtual boundaries is determined, based on the SPS virtual boundaries enabled flag,
wherein whether information on positions of the virtual boundaries and information on a number of the virtual boundaries are included in the SPS is determined based on a value of the SPS virtual boundaries present flag,
wherein based on that the value of the SPS virtual boundaries enabled flag is 1 and the value of the SPS virtual boundaries present flag is 0, the picture header information includes a picture header virtual boundaries present flag, and
wherein whether information on positions of the virtual boundaries and information on a number of the virtual boundaries are included in the picture header information is determined based on a value of the picture header virtual boundaries present flag.
2. The image decoding method of claim 1 , wherein the picture header information includes information on a number of vertical virtual boundaries, based on that the value of the picture header virtual boundaries present flag is 1.
3. The image decoding method of claim 2 , wherein the picture header information includes information on positions of the vertical virtual boundaries, and
wherein a number of pieces of the information on positions of the vertical virtual boundaries is determined based on the information on the number of vertical virtual boundaries.
4. The image decoding method of claim 1 , wherein the picture header information includes information on a number of horizontal virtual boundaries, based on that the value of the picture header virtual boundaries present flag is 1.
5. The image decoding method of claim 4 , wherein the picture header information includes information on positions of horizontal virtual boundaries, and
wherein a number of pieces of information on positions of the horizontal virtual boundaries is determined based on the information on the number of horizontal virtual boundaries.
6. The image decoding method of claim 1 , wherein information related to the in-loop filtering further includes a gradual decoding refresh (GDR) enabled flag, and
wherein the value of the SPS virtual boundaries enabled flag is 1, the value of the SPS virtual boundaries present flag is 0, and the value of the picture header virtual boundaries present flag is 1, based on that a value of the GDR enabled flag is 1.
7. An image encoding method performed by an encoding apparatus, comprising:
generating residual samples for a current block;
generating residual information, based on the residual samples for the current block;
generating in-loop filtering-related information for reconstructed samples of a current picture; and
encoding image information including the residual information and the in-loop filtering-related information,
wherein the image information includes a sequence parameter set (SPS) and picture header information,
wherein the SPS includes an SPS virtual boundaries enabled flag,
wherein the SPS further includes an SPS virtual boundaries present flag based on a value of the SPS virtual boundaries enabled flag,
wherein the in-loop filtering-related information includes the SPS virtual boundaries enabled flag related to whether an in-loop filtering process is performed across virtual boundaries,
wherein whether information on positions of the virtual boundaries and information on a number of the virtual boundaries are included in the SPS is determined based on a value of the SPS virtual boundaries present flag,
wherein based on that the value of the SPS virtual boundaries enabled flag is 1 and the value of the SPS virtual boundaries present flag is 0, the picture header information includes a picture header virtual boundaries present flag, and
wherein whether information on positions of the virtual boundaries and information on a number of the virtual boundaries are included in the picture header information is determined based on a value of the picture header virtual boundaries present flag.
8. A transmission method of data for an image, the method comprising:
obtaining a bitstream for the image, wherein the bitstream is generated based on generating residual samples for a current block, generating residual information, based on the residual samples for the current block, generating in-loop filtering-related information for reconstructed samples of a current picture, and encoding image information including the residual information and the in-loop filtering-related information; and
transmitting the data comprising the bitstream,
wherein the image information includes a sequence parameter set (SPS) and picture header information,
wherein the SPS includes an SPS virtual boundaries enabled flag,
wherein the SPS further includes an SPS virtual boundaries present flag based on a value of the SPS virtual boundaries enabled flag,
wherein the in-loop filtering-related information includes the SPS virtual boundaries enabled flag related to whether an in-loop filtering process is performed across virtual boundaries,
wherein whether information on positions of the virtual boundaries and information on a number of the virtual boundaries are included in the SPS is determined based on a value of the SPS virtual boundaries present flag,
wherein based on that the value of the SPS virtual boundaries enabled flag is 1 and the value of the SPS virtual boundaries present flag is 0, the picture header information includes a picture header virtual boundaries present flag, and
wherein whether information on positions of the virtual boundaries and information on a number of the virtual boundaries are included in the picture header information is determined based on a value of the picture header virtual boundaries present flag.