Image decoding method and apparatus, and image coding method and apparatus

A picture coding method, performed by a coding device, comprising:

• determining a predicted residual value of a pixel point according to a prediction manner of the pixel point, wherein the predicted residual value is configured to reflect a gradient of the pixel point, the prediction manner is configured to indicate a position of one or more reconstructed pixel points referenced when performing prediction on a pixel point, and the pixel point is any pixel point in a current coding block;
• determining a target quantization parameter (QP) value of a first pixel point according to the predicted residual value of the first pixel point, wherein the first pixel point is a target pixel point in the current coding block, and the target pixel point is a preset pixel point for adjusting the QP value;
• and
• performing quantization on the first pixel point according to the target QP value of the first pixel point.

An electronic device, comprising a processor and a memory, wherein the memory is configured to store computer instructions, and the processor is configured to call and run the computer instructions from the memory to perform operations comprising:

• determining a predicted residual value of a pixel point according to a prediction manner of the pixel point, wherein the predicted residual value is configured to reflect a gradient of the pixel point, the prediction manner is configured to indicate a position of one or more reconstructed pixel points referenced when performing prediction on a pixel point, and the pixel point is any pixel point in a current coding block;
• determining a target quantization parameter (QP) value of a first pixel point according to the predicted residual value of the first pixel point, wherein the first pixel point is a target pixel point in the current coding block, and the target pixel point is a preset pixel point for adjusting the QP value;
• and
• performing dequantization on the first pixel point according to the target QP value of the first pixel point.