An image decoding method according to this disclosure includes receiving image information including intra matrix-based intra prediction MIP) flag information related to whether an MIP is applied to a current block through a bitstream, deriving an intra prediction type for the current block as the MIP based on the intra MIP flag information, generating intra prediction samples for the current block based on the MIP, and generating reconstructed samples for the current block based on the intra prediction samples.