Image encoding/decoding method and apparatus for performing intra prediction, and method for transmitting bitstream

An image encoding method performed by an image encoding apparatus, the image encoding method comprising:

• determining whether to apply intra prediction to a current chroma block;
• deriving an intra prediction mode of the current chroma block based on intra prediction being applied to the current chroma block;
• generating a prediction block of the current chroma block, by performing intra prediction based on the intra prediction mode of the current chroma block;
• and
• encoding the intra prediction mode of the current chroma block based on an intra prediction mode of a corresponding luma block,
• wherein the intra prediction mode of the current chroma block is derived based on the intra prediction mode of the corresponding luma block and intra chroma prediction mode information of the current chroma block,
• wherein, based on the corresponding luma block not being intra predicted, the intra prediction mode of the current chroma block is derived based on a default intra prediction mode,
• wherein the deriving the intra prediction mode of the current chroma block comprises determining a prediction method at a predetermined position of the corresponding luma block,
• wherein, based on the prediction method at the predetermined position of the corresponding luma block being an intra block copy (IBC) prediction, the intra prediction mode of the current chroma block is derived based on the default intra prediction mode, and
• wherein the default intra prediction mode is a DC mode.

A non-transitory computer-readable medium storing a bitstream generated by an image encoding method, the image encoding method comprising:

• determining whether to apply intra prediction to a current chroma block;
• deriving an intra prediction mode of the current chroma block based on intra prediction being applied to the current chroma block;
• generating a prediction block of the current chroma block, by performing intra prediction based on the intra prediction mode of the current chroma block;
• and
• encoding the intra prediction mode of the current chroma block based on an intra prediction mode of a corresponding luma block,
• wherein the intra prediction mode of the current chroma block is derived based on the intra prediction mode of the corresponding luma block and intra chroma prediction mode information of the current chroma block,
• wherein, based on the corresponding luma block not being intra predicted, the intra prediction mode of the current chroma block is derived based on a default intra prediction mode,
• wherein the deriving the intra prediction mode of the current chroma block comprises determining a prediction method at a predetermined position of the corresponding luma block, and
• wherein, based on the prediction method at the predetermined position of the corresponding luma block being an intra block copy (IBC) prediction, the intra prediction mode of the current chroma block is derived based on the default intra prediction mode,
• wherein the default intra prediction mode is a DC mode.