An image decoding method performed by a decoding apparatus according to the present document comprises the steps of: obtaining a Block-based Delta Pulse Code Modulation (BDPCM) available flag indicating whether or not BDPCM is available for a chroma block and a luma block; obtaining BDPCM-related information for a current luma block and current chroma blocks on the basis of the BDPCM available flag; and generating reconstructed samples for the current luma block and the current chroma blocks on the basis of the BDPCM-related information.