Intra-Frame Prediction and Decoding Methods and Apparatuses for Image Signal

An intra-frame decoding method for a signal component sampling point of an image block, comprising:

• obtaining, from a video code stream, prediction mode information of a first signal component of a current block;
• determining a prediction mode of the first signal component of the current block from a prediction mode set of the first signal component of the current block according to the prediction mode information of the first signal component of the current block, wherein the prediction mode set of the first signal component of the current block comprises at least one of a linear model above (LMA) mode and a linear model left (LML) mode;
• obtaining a predicted value of a first signal component sampling point of the current block according to the prediction mode of the first signal component of the current block;
• and
• obtaining a reconstructed value of the first signal component sampling point of the current block according to the predicted value of the first signal component sampling point of the current block.

An intra-frame decoding method for a signal component sampling point of an image block, comprising:

• obtaining, from a video code stream, prediction mode information of a first signal component of a current block;
• determining a prediction mode of the first signal component of the current block from a prediction mode set of the first signal component of the current block according to the prediction mode information of the first signal component of the current block, wherein the prediction mode set of the first signal component comprises a prediction mode based on a correlation model, and the prediction mode based on the correlation model is determined depending on a prediction mode of a second signal component of the current block;
• obtaining a predicted value of a first signal component sampling point of the current block according to the prediction mode of the first signal component of the current block;
• and
• obtaining a reconstructed value of the first signal component sampling point of the current block according to the predicted value of the first signal component sampling point of the current block.