AN IMAGE CODING APPARATUS AND METHOD THEREOF BASED ON A QUANTIZATION PARAMETER DERIVATION

摘要

According to an embodiment of the present invention, there is provided a picture decoding method performed by a decoding apparatus. The picture decoding method may include decoding image information including information on a quantization parameter (QP); deriving an expected average luma value of the current block from available neighboring samples; deriving a quantization parameter offset (QP offset) for deriving a luma quantization parameter (luma QP) based on the expected average luma value and the information on the QP; deriving a luma QP based on the QP offset; performing inverse quantization on the quantization group including the current block based on the derived luma QP; generating a residual sample for the current block based on inverse quantization; generating a prediction sample for the current block based on the image information; and generating a reconstructed sample for the current block based on the residual sample for the current block and the prediction sample for the current block.