Chroma prediction method and device

A method of block prediction, comprising:

• obtaining first processing information indicating whether downsampling is performed on a luma component of a to-be-processed image block;
• obtaining second processing information indicating whether downsampling is performed on a chroma component of the to-be-processed image block, wherein the second processing information is different from the first processing information;
• reconstructing the luma component based on the first processing information;
• reconstructing the chroma component based on the second processing information;
• when the first processing information indicates that downsampling is performed on the luma component of the to-be-processed image block, performing a first upsampling processing on the luma component based on the first processing information to obtain a reconstructed luma block of the to-be-processed image block, wherein the first upsampling processing is a reverse processing of the downsampling indicated by the first processing information and performed on the luma component of the to-be-processed image block;
• and
• when the second processing information indicates that downsampling is performed on the chroma component of the to-be-processed image block, performing a second upsampling processing on the chroma component based on the second processing information to obtain a reconstructed chroma block of the to-be-processed image block, wherein the second upsampling processing is a reverse processing of the downsampling indicated by the second processing information and performed on the chroma component of the to-be-processed image block.

A non-transitory computer-readable storage medium storing instructions that when executed by one or more processors, cause the one or more processors to:

• obtain first processing information indicating whether downsampling is performed on a luma component of a to-be-processed image block;
• obtain second processing information indicating whether downsampling is performed on a chroma component of the to-be-processed image block, wherein the second processing information is different from the first processing information;
• reconstruct the luma component based on the first processing information;
• reconstruct the chroma component based on the second processing information;
• when the first processing information indicates that downsampling is performed on the luma component of the to-be-processed image block, perform a first upsampling processing on the luma component based on the first processing information to obtain a reconstructed luma block of the to-be-processed image block, wherein the first upsampling processing is a reverse processing of the downsampling indicated by the first processing information and performed on the luma component of the to-be-processed image block;
• and
• when the second processing information indicates that downsampling is performed on the chroma component of the to-be-processed image block, perform a second upsampling processing on the chroma component based on the second processing information to obtain a reconstructed chroma block of the to-be-processed image block, wherein the second upsampling processing is a reverse processing of the downsampling indicated by the second processing information and performed on the chroma component of the to-be-processed image block.