Encoder, decoder, encoding method, and decoding method

A decoder comprising:

• circuitry;
• and
• memory coupled to the circuitry, wherein
• in operation, the circuitry:
• generates, in an inter prediction mode, a first prediction image of a current block to be processed, based on a derived motion vector;
• and
• generates a final prediction image of the current block by applying an update process to the first prediction image,
• candidates for the update process include a first process and a second process,
• the first process is a bi-directional optical flow (BDOF) process,
• the second process is a process of mixing the first prediction image with a second prediction image generated in intra prediction for the current block, and
• in the applying of the update process, the first process and the second process are mutually exclusively applied.

An encoding method, comprising:

• generating, in an inter prediction mode, a first prediction image of a current block to be processed, based on a derived motion vector;
• and
• generating a final prediction image of the current block by applying an update process to the first prediction image, wherein
• candidates for the update process include a first process and a second process,
• the first process is a bi-directional optical flow (BDOF) process,
• the second process is a process of mixing the first prediction image with a second prediction image generated in intra prediction for the current block, and
• in the applying of the update process, the first process and the second process are mutually exclusively applied.

A decoding method, comprising:

• generating, in an inter prediction mode, a first prediction image of a current block to be processed, based on a derived motion vector;
• and
• generating a final prediction image of the current block by applying an update process to the first prediction image, wherein
• candidates for the update process include a first process and a second process,
• the first process is a bi-directional optical flow (BDOF) process,
• the second process is a process of mixing the first prediction image with a second prediction image generated in intra prediction for the current block, and
• in the applying of the update process, the first process and the second process are mutually exclusively applied.