Image encoding/decoding method and device using maximum transform size restriction of chroma component encoding block, and method for transmitting bitstream

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

• determining a current block by splitting an image;
• generating a prediction block of the current block by performing intra block copy (IBC) prediction on the current block;
• generating a residual block of the current block based on the prediction block;
• and
• encoding prediction mode information of the current block,
• wherein the residual block is encoded based on a size of a transform block of the current block,
• wherein the size of the transform block is determined based on a color component of the current block, and
• wherein the size of the transform block is determined based on a color format, based on the color component of the current block being a chroma component,
• wherein the current block is a chroma block, and
• wherein a postion of a top-left sample of the transform block is determined based on a position of a top-left sample of a luma transform block corresponding to the current block and the color format of the current block.

A method of transmitting a bitstream generated by an image encoding method, the image encoding method comprising:

• determining a current block by splitting an image;
• generating a prediction block of the current block by performing intra block copy (IBC) prediction on the current block;
• generating a residual block of the current block based on the prediction block;
• and
• encoding prediction mode information of the current block,
• wherein the residual block is encoded based on a size of a transform block of the current block,
• wherein the size of the transform block is determined based on a color component of the current block,
• wherein the size of the transform block is determined based on a color format of the current block, based on the color component of the current block being a chroma component, and
• wherein the current block is a chroma block, and
• wherein a postion of a top-left sample of the transform block is determined based on a position of a top-left sample of a luma transform block corresponding to the current block and the color format of the current block.