US 12,294,718 B2
Method, apparatus and system for encoding and decoding a tree of blocks of video samples
Christopher James Rosewarne, Concord West (AU)
Assigned to Canon Kabushiki Kaisha, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on May 31, 2024, as Appl. No. 18/680,564.
Application 18/680,564 is a continuation of application No. 17/435,952, granted, now 12,088,822, previously published as PCT/AU2020/050028, filed on Jan. 20, 2020.
Claims priority of application No. 2019201653 (AU), filed on Mar. 11, 2019.
Prior Publication US 2024/0323395 A1, Sep. 26, 2024
Int. Cl. H04N 19/146 (2014.01); H04N 19/132 (2014.01); H04N 19/176 (2014.01); H04N 19/186 (2014.01)
CPC H04N 19/146 (2014.11) [H04N 19/132 (2014.11); H04N 19/176 (2014.11); H04N 19/186 (2014.11)] 10 Claims
OG exemplary drawing
 
1. A method of decoding, from a bitstream, a transform block of an image frame, the method comprising:
determining a chroma format of the image frame from a plurality of chroma formats including a 4:2:0 chroma format and a 4:2:2 chroma format;
splitting a coding tree unit into one or more coding units each of which includes a luma coding block and a chroma coding block;
determining a sub-block of the transform block which is a luma transform block for a luma coding block or a chroma transform block for a chroma coding block, so that an area of the sub-block corresponds to 16 samples, the sub-block being a unit for scanning coefficients in the transform block; and
decoding the transform block, from the bitstream, using the sub-block,
wherein in a case where a block size of a chroma coding block of a given coding unit including a luma coding block and the chroma coding block in the coding tree unit having the 4:2:0 chroma format is 8×2, a vertical ternary split is not allowed for the chroma coding block in the given coding unit even if a vertical ternary split for the luma coding block in the given coding unit is performed,
wherein in a case where the luma coding block in the given coding unit is split by a vertical ternary split and the chroma coding block in the given coding unit is not split by a vertical ternary split, the chroma coding block in the given coding unit is arranged at a position corresponding to three luma coding blocks obtained by a vertical ternary split for the luma coding block in the given coding unit,
wherein, the transform block is decoded based on (i) a width and a height of the transform block, and (ii) whether the transform block is the luma transform block or the chroma transform block, and
wherein in a case where base-2 log of the width of the transform block is 4 and base-2 log of the height of the transform block is 4, base-2 log of a width of the sub-block of the transform block and base-2 log of a height of the sub-block of the transform block are determined from (i) base-2 log of the width of the transform block and base-2 log of the height of the transform block, and determined independently of both (ii) whether the transform block is the luma transform block or the chroma transform block and (iii) the chroma format of the image frame, when determining base-2 log of the width of the sub-block of the transform block and base-2 log of the height of the sub-block of the transform block.