Method and apparatus for intra prediction of picture block

A method for intra prediction of a picture block, comprising:

• parsing a received bitstream to obtain a first identifier;
• when the first identifier indicates that a chroma prediction mode of a current block is not a cross-component linear model (CCLM) mode, constructing a chroma intra mode set for the current block, wherein the chroma intra mode set comprises a determined chroma prediction mode of a picture block that is not spatially adjacent to the current block in a picture in which the current block is located;
• parsing the received bitstream to obtain a second identifier, wherein the second identifier indicates that a candidate chroma prediction mode in the chroma intra mode set is used as the chroma prediction mode of the current block;
• and
• obtaining a chroma prediction value of the current block based on the chroma prediction mode of the current block;
• wherein the current block has a width of w and a height of h, the picture in which the current block is located comprises M groups of picture blocks not spatially adjacent to the current block, and each group of picture blocks not spatially adjacent to the current block has a group number, wherein a group of picture blocks with a group number i comprises picture blocks in which pixel set basic units in the following coordinate positions in a virtual coordinate system are located:
• (−i×w,−i×h), (1+m×w,−i×h), (−m×w,−i×h), (−i×w,−m×h), and (−i×w,m×h+1), wherein
• m is an integer in a range from 0 to i−1;
• M, i, w, and h are positive integers;
• and
• i is not greater than M, and a value of i is not 1.

An apparatus, comprising:

• a memory and a processor, wherein
• the memory is configured to store a program instruction;
• and
• the processor is configured to invoke and execute the program instruction stored in the memory, to perform:
• constructing a first luma intra mode set for a current block, wherein
• the first luma intra mode set is a subset of a plurality of preset candidate luma prediction modes;
• and
• the first luma intra mode set comprises a determined luma prediction mode of a picture block that is not spatially adjacent to the current block in a picture in which the current block is located;
• parsing a received bitstream to obtain a first identifier;
• when the first identifier indicates that a luma prediction mode of the current block belongs to the first luma intra mode set, parsing the received bitstream to obtain a second identifier, wherein the second identifier indicates that a candidate luma prediction mode in the first luma intra mode set is used as the luma prediction mode of the current block;
• and
• obtaining a luma prediction value of the current block based on the luma prediction mode of the current block;
• wherein the current block has a width of w and a height of h, the picture in which the current block is located comprises M groups of picture blocks not spatially adjacent to the current block, and each group of picture blocks not spatially adjacent to the current block has a group number, wherein a group of picture blocks with a group number i comprises picture blocks in which pixel set basic units in the following coordinate positions in a virtual coordinate system are located:
• (−i×w,−i×h), (1+m×w,−i×h), (−m×w,−i×h), (−i×w,−m×h), and (−i×w,m×h+1), wherein m is an integer in a range from 0 to i−1;
• M, i, w, and h are positive integers;
• and
• i is not greater than M, and a value of i is not 1.