Method and apparatus of cross-component linear model prediction with refined parameters in video coding system
A method and apparatus for video coding are disclosed. According to the method for the decoder side, encoded data associated with a current block comprising a first-colour block and a second-colour block are received. An inherited model parameter set is determined from a previously coded block coded in a first CCLM related mode, wherein the inherited model parameter set comprises a first scaling parameter associated with the first CCLM related mode. A final inherited model parameter set is derived if an update value for the inherited model parameter set is determined, where the final inherited model parameter set is determined based on the first scaling parameter and the update value. Then, the encoded data associated with the second-colour block are decoded using prediction data based on an updated CCLM related model associated with the final inherited model parameter set. A method and apparatus for the encoder side are also disclosed.
1 . A method of decoding colour pictures using coding tools including one or more CCLM (Cross Colour Linear Model) related modes, the method comprising:
receiving encoded data associated with a current block comprising a first-colour block and a second-colour block;
determining an inherited model parameter set from a previously coded block coded in a first CCLM related mode, wherein the inherited model parameter set comprises a first scaling parameter associated with the first CCLM related mode;
deriving a final inherited model parameter set if an update value for the inherited model parameter set is determined, wherein the final inherited model parameter set is determined based on the first scaling parameter and the update value; and
decoding the encoded data associated with the second-colour block using prediction data based on an updated CCLM related model associated with the final inherited model parameter set.
2 . The method of claim 1 , wherein the previously coded block corresponds to a neighbouring block coded in the first CCLM related mode.
3 . The method of claim 2 , wherein the neighbouring block is selected from a merge candidate list comprising spatial and temporal neighbouring blocks coded in one CCLM related mode.
4 . The method of claim 1 , wherein the previously coded block is selected from a historical candidate list comprising one or more recently coded blocks using one CCLM related mode.
5 . The method of claim 1 , wherein the update value is always zero and the updated CCLM related model is the same as the first CCLM related mode.
6 . The method of claim 1 , wherein the final inherited model parameter set is always the same as the inherited model parameter set without update.
7 . The method of claim 1 , wherein the update value is parsed from a bitstream comprising the encoded data associated with the current block.
8 . The method of claim 1 , wherein a final scaling parameter is determined based on the first scaling parameter and the update value, and the final scaling parameter inherits an MSB (most significant bits) part of a scaling parameter of the first CCLM related mode and an LSB (least significant bits) part of the final scaling parameter is determined according to the update value.
9 . A method of encoding colour pictures using coding tools including one or more CCLM (Cross Colour Linear Model) related modes, the method comprising:
receiving pixel data associated with a current block comprising a first-colour block and a second-colour block;
determining an inherited model parameter set from a previously coded block coded in a first CCLM related mode, wherein the inherited model parameter set comprises a first scaling parameter associated with the first CCLM related mode;
deriving a final inherited model parameter set if an update value for the inherited model parameter set is determined, wherein the final inherited model parameter set is determined based on the first scaling parameter and the update value; and
encoding the second-colour block using prediction data based on an updated CCLM related model associated with the final inherited model parameter set.
10 . The method of claim 9 , wherein the previously coded block corresponds to a neighbouring block coded in the first CCLM related mode.
11 . The method of claim 10 , wherein the neighbouring block is selected from a merge 11 candidate list comprising spatial and temporal neighbouring blocks coded in one CCLM related mode.
12 . The method of claim 9 , wherein the previously coded block is selected from a historical candidate list comprising one or more recently coded blocks using one CCLM related mode.
13 . The method of claim 9 , wherein a final scaling parameter is determined based on the first scaling parameter and the update value, and the final scaling parameter inherits an MSB (most significant bits) part of a scaling parameter of the first CCLM related mode and an LSB (least significant bits) part of the final scaling parameter is determined according to the update value.
14 . The method of claim 9 further comprises signalling the update value in a bitstream comprising coded data of the current block.
15 . An apparatus for decoding colour pictures using coding tools including one or more CCLM (Cross Colour Linear Model) related modes, the apparatus comprising one or more electronics or processors arranged to:
receive encoded data associated with a current block comprising a first-colour block and a second-colour block;
determine an inherited model parameter set from a previously coded block coded in a first CCLM related mode, wherein the inherited model parameter set comprises a first scaling parameter associated with the first CCLM related mode;
derive a final inherited model parameter set if an update value for the inherited model parameter set is determined, wherein the final inherited model parameter set is determined based on the first scaling parameter and the update value; and
decode the encoded data associated with the second-colour block using prediction data based on an updated CCLM related model associated with the final inherited model parameter set.
16 . An apparatus for encoding colour pictures using coding tools including one or more CCLM (Cross Colour Linear Model) related modes, the apparatus comprising one or more electronics or processors arranged to:
receive pixel data associated with a current block comprising a first-colour block and a second-colour block;
determine an inherited model parameter set from a previously coded block coded in a first CCLM related mode, wherein the inherited model parameter set comprises a first scaling parameter associated with the first CCLM related mode;
derive a final inherited model parameter set if an update value for the inherited model parameter set is determined, wherein the final inherited model parameter set is determined based on the first scaling parameter and the update value; and
encode the second-colour block using prediction data based on an updated CCLM related model associated with the final inherited model parameter set.