Image coding/decoding method, and storage medium

A picture encoding method, applicable to an encoder, the method comprising:

• determining a size of a current block;
• when encoding the current block by using a Matrix-based Intra Prediction (MIP) mode,
• determining a value of a MIP block size index number corresponding to the current block according to the size of the current block;
• determining a first offset for calculating a second offset;
• calculating the second offset based on the MIP block size index number, the first offset and reconstructed values of adjacent pixels corresponding to the current block;
• determining a first prediction value of the current block according to the second offset;
• and
• encoding the current block based on the first prediction value and residuals of the current block.

A non-transitory computer-readable storage medium having stored thereon instructions and a bitstream, wherein when the instructions are executed by a processor, the instructions implement the steps of a picture decoding method to decode the bitstream to generate a picture, the picture decoding method comprising:

• decoding a bitstream to obtain a size, a coding mode of a current block;
• when the coding mode of the current block is a Matrix-based Intra Prediction (MIP) mode,
• determining a value of a MIP block size index number corresponding to the current block according to the size of the current block;
• determining a first offset for calculating a second offset;
• calculating the second offset based on the MIP block size index number, the first offset and reconstructed values of adjacent pixels corresponding to the current block;
• determining a first prediction value of the current block according to the second offset;
• and
• determining a reconstructed value of the current block based on the first prediction value.