Method and apparatus of decoder side intra mode derivation based most probable modes list construction in video coding system
A method and apparatus for generating an extended MPM (Most Probable Modes) list by adding the target DIMD candidate and at least one neighbouring mode of the target DIMD candidate to an initial MPM list. A target DIMD candidate is determined for the current block based on a DIMD process using statistics or histogram of angle field derived from a template of the current block. At least one neighbouring mode of the target DIMD candidate is generated by adding an offset to a corresponding mode number of the target DIMD candidate. The offset corresponds to a non-zero integer. An extended MPM (Most Probable Modes) list is generated by adding the target DIMD candidate and at least one neighbouring mode of the target DIMD candidate to an initial MPM list. The current block is encoded or decoded using information that includes the extended MPM list.
1 . A method of video coding, the method comprising:
receiving pixel data associated with a current block at an encoder side or coded data associated with the current block to be decoded at a decoder side;
determining a target DIMD (Decoder Side Intra Mode Derivation) candidate for the current block based on a DIMD process using statistics or histogram of angle field derived from a template of the current block;
generating at least one neighbouring mode of the target DIMD candidate by adding an offset to a corresponding mode number of the target DIMD candidate, and wherein the offset corresponds to a non-zero integer;
generating an extended MPM (Most Probable Modes) list by adding the target DIMD candidate and said at least one neighbouring mode of the target DIMD candidate to an initial MPM list, wherein said at least one neighbouring mode of the target DIMD candidate corresponds to a plurality of neighbouring modes of the target DIMD candidate and the plurality of neighbouring modes of the target DIMD candidate are added to the initial MPM list in an interleaved manner according to distances between the plurality of neighbouring modes of the target DIMD candidate and the target DIMD candidate; and
encoding or decoding the current block using information comprising the extended MPM list.
2 . The method of claim 1 , wherein the plurality of neighbouring modes of the target DIMD candidate are added to the initial MPM in an order according to (the target DIMD candidate−1), (the target DIMD candidate+1), (the target DIMD candidate−2), (the target DIMD candidate+2), and so on.
3 . The method of claim 1 , wherein a second target DIMD candidate is generated for the current block based on the DIMD process and the second target DIMD candidate is added to the initial MPM list at a location immediately after the target DIMD candidate.
4 . The method of claim 3 , wherein at least one second neighbouring mode of the second target DIMD candidate is generated by adding a second offset to a corresponding mode number of the second target DIMD candidate and the second offset corresponds to a non-zero integer, and wherein said at least one second neighbouring mode of the second target DIMD candidate is added to the initial MPM list to form the extended MPM list.
5 . The method of claim 4 , wherein said at least one second neighbouring mode of the second target DIMD candidate corresponds to a plurality of second neighbouring modes of the second target DIMD candidate, and the plurality of second neighbouring modes of the second target DIMD candidate are added to the initial MPM list in an interleaved manner according to distances between the plurality of second neighbouring modes of the second target DIMD candidate and the second target DIMD candidate.
6 . The method of claim 5 , wherein the plurality of second neighbouring modes of the second target DIMD candidate are added to the initial MPM in an order according to (the second target DIMD candidate−1), (the second target DIMD candidate+1), (the second target DIMD candidate−2), (the second target DIMD candidate+2), and so on.
7 . The method of claim 4 , wherein said at least one second neighbouring mode of the second target DIMD candidate is added to the initial MPM list at the location immediately after said at least one neighbouring mode of the target DIMD candidate.
8 . The method of claim 1 , wherein a pruning process is applied to the extended MPM list after a new candidate is added.
9 . An apparatus for video coding, the apparatus comprising one or more electronics or processors arranged to:
receive pixel data associated with a current block at an encoder side or coded data associated with the current block to be decoded at a decoder side;
determine a target DIMD (Decoder Side Intra Mode Derivation) candidate for the current block based on a DIMD process using statistics or histogram of angle field derived from a template of the current block;
generate at least one neighbouring mode of the target DIMD candidate by adding an offset to a corresponding mode number of the target DIMD candidate, and wherein the offset corresponds to a non-zero integer;
generate an extended MPM (Most Probable Modes) list by adding the target DIMD candidate and said at least one neighbouring mode of the target DIMD candidate to an initial MPM list, wherein said at least one neighbouring mode of the target DIMD candidate corresponds to a plurality of neighbouring modes of the target DIMD candidate and the plurality of neighbouring modes of the target DIMD candidate are added to the initial MPM list in an interleaved manner according to distances between the plurality of neighbouring modes of the target DIMD candidate and the target DIMD candidate; and
encode or decode the current block using information comprising the extended MPM list.