| CPC H04N 19/11 (2014.11) [H04N 19/119 (2014.11); H04N 19/159 (2014.11); H04N 19/176 (2014.11); H04N 19/186 (2014.11); H04N 19/593 (2014.11); H04N 19/96 (2014.11)] | 5 Claims |

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1. A method of decoding coding blocks of a coding tree unit for an image frame, from a bitstream, the method comprising:
decoding information used to determine a chroma format of the image frame;
determining the chroma format of the image frame based on the information, wherein the determined chroma format is 4:2:0;
recursively splitting the coding tree unit into one or more coding units each of which has a luma coding block and chroma coding blocks, using a single tree;
determining whether further split for a chroma coding block is allowed,
wherein, if a block size of a luma coding block of a current coding unit is 8×8 and a block size of chroma coding blocks of the current coding unit is 4×4, a quad split for the chroma coding blocks of the current coding unit is not allowed even if the luma coding block of the current coding unit is split by a quad split, and
the chroma coding blocks, having the block size of 4×4, of the current coding unit are collocated with four luma coding blocks resulted from a quad split for the luma coding block, having the block size of 8×8, of the current coding unit if the luma coding block of the current coding unit is split by a quad split;
determining that the chroma coding blocks of the current coding unit are to be decoded using intra prediction if the block size of the luma coding block of the current coding unit is 8×8, the block size of the chroma coding blocks of the current coding unit is 4×4, and a current split mode for the current coding unit is a quad split; and
decoding the chroma coding blocks of the current coding unit using intra prediction if it is determined that the chroma coding blocks of the current coding unit are to be decoded using intra prediction.
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