Method and device for encoding/decoding image using color space conversion, and method for transmitting bitstream

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

• deriving quantization parameter of a current block based on a color space transform for a residual sample of the current block;
• deriving transformation coefficient of the current block based on the quantization parameter;
• deriving the residual sample of the current block based on the transformation coefficient;
• and
• modifying a value of the residual sample based on the color space transform being applied;
• wherein the quantization parameter is derived by clipping operation based on a value of transformation skip flag of the current block;
• wherein the clipping operation comprises adjusting a value of the quantization parameter to be in a range from a predetermined lower value to a predetermined upper value, inclusive,
• wherein the predetermined upper value is derived based on quantization parameter range offset and a predetermined constant value.