Decoder, decoding method, and related non-transitory computer readable medium
A decoder includes memory and a processor coupled to the memory and configured to: generate a first coefficient value by applying a CCALF (cross component adaptive loop filtering) process to a first reconstructed image sample of a luma component; clip the first coefficient value such that the clipped first coefficient value is within a first range from −2 7 to 2 7 −1; generate a second coefficient value by applying an ALF (adaptive loop filtering) process to a second reconstructed image sample of a chroma component; clip the second coefficient value such that the clipped second coefficient value is within a second range different from the first range; generate a third coefficient value by adding the clipped first coefficient value to the clipped second coefficient value; and generate a third reconstructed image sample of the chroma component using the third coefficient value.
1 . An encoder comprising:
circuitry; and
memory coupled to the circuitry,
wherein the circuitry, in operation:
generates a first coefficient value by applying a CCALF (cross component adaptive loop filtering) process to a first reconstructed image sample of a luma component;
clips the first coefficient value such that the clipped first coefficient value is within a first range from −2 7 to 2 7 −1 indicated by a first parameter;
generates a second coefficient value by applying an ALF (adaptive loop filtering) process to a second reconstructed image sample of a chroma component;
clips the second coefficient value such that the clipped second coefficient value is within a second range different from the first range, the second range being indicated by a second parameter;
generates a third coefficient value by adding the clipped first coefficient value to the clipped second coefficient value; and
encodes a third reconstructed image sample of the chroma component using the third coefficient value.
2 . An encoding method comprising:
generating a first coefficient value by applying a CCALF (cross component adaptive loop filtering) process to a first reconstructed image sample of a luma component;
clipping the first coefficient value such that the clipped first coefficient value is within a first range from −2 7 to 2 7 −1 indicated by a first parameter;
generating a second coefficient value by applying an ALF (adaptive loop filtering) process to a second reconstructed image sample of a chroma component;
clipping the second coefficient value such that the clipped second coefficient value is within a second range different from the first range, the second range being indicated by a second parameter;
generating a third coefficient value by adding the clipped first coefficient value to the clipped second coefficient value; and
encoding a third reconstructed image sample of the chroma component using the third coefficient value.
3 . A bitstream transmission method comprising:
generating a bitstream; and
transmitting the bitstream to an image decoding apparatus, the bitstream including clip information according to which the image decoding apparatus performs a CCALF (cross component adaptive loop filtering) process and an ALF (adaptive loop filtering) process on a first reconstructed image sample of a luma component and a second reconstructed image sample of a chroma component, respectively, in the CCALF process, (i) a first coefficient value being generated and (ii) the first coefficient value being clipped such that the clipped first coefficient value is within a first range from −2 7 to 2 7 −1 indicated by a first parameter, in the ALF process, (i) a second coefficient value being generated and (ii) the second coefficient value being clipped such that the clipped second coefficient value is within a second range different from the first range, the second range being indicated by a second parameter, the clipped first coefficient value being added to the clipped second coefficient value to generate a third coefficient value, the third coefficient value being used to decode a third reconstructed image sample of the chroma component.