Template matching based intra prediction

An apparatus for video decoding, comprising:

• processing circuitry configured to:
• receive coded information of a coding unit (CU), a template region, and a plurality of reference regions from a coded video bitstream, the coded information including a first syntax element indicating whether the CU is predicted based on a template matching based multiple reference line (MRL) intra prediction mode and a second syntax element indicating whether the CU is intra predicted based on template based intra mode derivation (TIMD) mode including a set of candidate intra prediction modes, the template region being adjacent to the CU and each reference region of the plurality of reference regions comprising at least one reference line portion;
• in response to the second syntax element indicating that the CU is not intra predicted based on TIMD mode, decode a syntax element associated with another intra coding mode, the other intra coding mode including one of matrix-based intra prediction (MIP) and most probable mode (MPM);
• in response to the first syntax element indicating that the CU is predicted based on the template matching based MRL intra prediction mode, determine a plurality of cost values associated with the template region and respectively corresponding to each of the plurality of reference regions, wherein each cost value is between (i) respective prediction samples of the template region based on samples in a respective one of the plurality of reference regions, and (ii) reconstructed samples of the template region corresponding to the respective prediction samples;
• select a reference region from the plurality of reference regions, the selected reference region corresponding to a lowest one among the plurality of cost values;
• and
• reconstruct samples of the CU based on the samples in the selected reference region.

A non-transitory computer readable storage medium storing instructions which when executed by at least one processor cause the at least one processor to perform:

• receiving coded information of a coding unit (CU), a template region, and a plurality of reference regions from a coded video bitstream, the coded information including a first syntax element indicating whether the CU is predicted based on a template matching based multiple reference line (MRL) intra prediction mode and a second syntax element indicating whether the CU is intra predicted based on template based intra mode derivation (TIMD) mode including a set of candidate intra prediction modes, the template region being adjacent to the CU and each reference region of the plurality of reference regions comprising at least one reference line portion;
• in response to the second syntax element indicating that the CU is not intra predicted based on TIMD mode, decoding a syntax element associated with another intra coding mode, the other intra coding mode including one of matrix-based intra prediction (MIP) and most probable mode (MPM);
• in response to the first syntax element indicating that the CU is predicted based on the template matching based MRL intra prediction mode, determining a plurality of cost values associated with the template region and respectively corresponding to each of the plurality of reference regions, wherein each cost value is between (i) respective prediction samples of the template region based on samples in a respective one of the plurality of reference regions, and (ii) reconstructed samples of the template region corresponding to the respective prediction samples;
• selecting a reference region from the plurality of reference regions, the selected reference region corresponding to a lowest one among the plurality of cost values;
• and
• reconstructing samples of the CU based on the samples in the selected reference region.