Method for colour component prediction, encoder, decoder and storage medium

A method for colour component prediction, applicable for a decoder and comprising:

• parsing a bitstream to acquire prediction parameters of a current block, the prediction parameters comprising a prediction mode parameter;
• when the prediction mode parameter indicates that a Matrix-based Intra Prediction (MIP) mode is adopted to determine an intra prediction value of the current block, determining an MIP weight matrix of the current block, a shift factor of the current block and an MIP input sample matrix of the current block;
• and
• determining the intra prediction value of the current block according to the MIP weight matrix, the shift factor and the MIP input sample matrix,
• wherein the MIP weight matrix of the current block is determined at least according to a block size index value of the current block;
• when both a width and a height of the current block are equal to 4, setting the block size index value of the current block equal to 0;
• when both the width and height of the current block are equal to 8 or only one of the width and height of the current block is equal to 4, setting the block size index value of the current block equal to 1;
• or
• when both the width and height of the current block do not meet the above conditions, setting the block size index value of the current block equal to 2,
• wherein determining the intra prediction value of the current block according to the MIP weight matrix, the shift factor and the MIP input sample matrix comprises:
• performing matrix multiplication processing on the MIP input sample matrix, the MIP weight matrix and the shift factor by use of a preset calculation model to obtain an MIP-based prediction block of the current block.

An encoder, comprising a memory and a processor, wherein

• the memory is configured to store computer programs capable of running in the processor;
• and
• the processor is configured to run the computer programs to:
• determine prediction parameters of a current block, the prediction parameters comprising a prediction mode parameter;
• when the prediction mode parameter indicates that a Matrix-based Intra Prediction (MIP) mode is adopted to determine an intra prediction value of the current block, determine an MIP weight matrix of the current block, a shift factor of the current block and an MIP input sample matrix of the current block;
• and
• determine the intra prediction value of the current block according to the MIP weight matrix, the shift factor and the MIP input sample matrix,
• wherein the MIP weight matrix of the current block is at least determined according to a block size index value of the current block;
• set the block size index value of the current block equal to 0 when both a width and a height of the current block are equal to 4;
• set the block size index value of the current block equal to 1 when both the width and height of the current block are equal to 8 or only one of the width and height of the current block is equal to 4;
• or
• set the block size index value of the current block equal to 2 when both the width and height of the current block do not meet the above conditions,
• wherein the processor is further configured to run the computer programs to:
• perform matrix multiplication processing on the MIP input sample matrix, the MIP weight matrix and the shift factor by use of a preset calculation model to obtain an MIP-based prediction block of the current block.

A decoder, comprising a memory and a processor, wherein

• the memory is configured to store computer programs capable of running in the processor;
• and
• the processor is configured to run the computer programs to:
• parse a bitstream to acquire prediction parameters of a current block, the prediction parameters comprising a prediction mode parameter;
• when the prediction mode parameter indicates that a Matrix-based Intra Prediction (MIP) mode is adopted to determine an intra prediction value of the current block, determine an MIP weight matrix of the current block, a shift factor of the current block and an MIP input sample matrix of the current block;
• and
• determine the intra prediction value of the current block according to the MIP weight matrix, the shift factor and the MIP input sample matrix,
• wherein the MIP weight matrix of the current block is determined at least according to a block size index value of the current block;
• set the block size index value of the current block equal to 0 when both a width and a height of the current block are equal to 4;
• set the block size index value of the current block equal to 1 when both the width and height of the current block are equal to 8 or only one of the width and height of the current block is equal to 4;
• or
• set the block size index value of the current block equal to 2 when both the width and height of the current block do not meet the above conditions,
• wherein the processor is further configured to run the computer programs to:
• perform matrix multiplication processing on the MIP input sample matrix, the MIP weight matrix and the shift factor by use of a preset calculation model to obtain an MIP-based prediction block of the current block.