Method and Apparatus of Matrix-Based Intra Prediction for Video Coding

An apparatus of video coding using a coding mode belonging to a mode group comprising a regular Intra Prediction mode and a Matrix-based Intra Prediction (MIP) mode, the apparatus of video coding comprising one or more electronic circuits or processors arranged to:

• receive input data related to a current block in a current picture at a video encoder side or receive a video bitstream comprising coded data of the current block at a video decoder side;
• when the MIP mode is applied to the current block:
• check availability for a target reference boundary region comprising left reference boundary samples and top reference boundary samples, wherein the left reference boundary samples and the top reference boundary samples are checked jointly for the current block;
• derive a reduced predictor, wherein a process to derive the reduced predictor comprises to apply matrix multiplication on a boundary vector and to add an offset, wherein the boundary vector is derived from the target reference boundary region, and wherein at least one unavailable samples is padded if there exists any unavailable sample in the target reference boundary region;
• and
• encode or decode the current block using a MIP predictor derived from the reduced predictor.

A method of video coding, the method comprising:

• receiving input data related to a current block in a current picture at a video encoder side or receiving a video bitstream comprising coded data of the current block at a video decoder side;
• deriving target samples from a target reference boundary region comprising left reference boundary samples and top reference boundary samples;
• deriving a reduced predictor, wherein said deriving the reduced predictor comprises applying matrix multiplication on a boundary vector and adding an offset, and wherein the boundary vector is derived from the target reference boundary region;
• and
• if current block size is larger than reduced predictor size:
• generating an up-sampled reduced predictor having the current block size by applying horizontal and vertical bi-linear interpolation to the reduced predictor and selected original left reference boundary samples and selected original top reference boundary samples at specific positions;
• and
• encoding or decoding the current block using the up-sampled reduced predictor.

An apparatus of video coding, the apparatus of video coding comprising one or more electronic circuits or processors arranged to:

• receive input data related to a current block in a current picture at a video encoder side or receive a video bitstream comprising coded data of the current block at a video decoder side;
• derive target samples from a target reference boundary region comprising left reference boundary samples and top reference boundary samples;
• derive a reduced predictor, wherein a process to derive the reduced predictor comprises to apply matrix multiplication on a boundary vector and to add an offset, and wherein the boundary vector is derived from the target reference boundary region;
• and
• if current block size is larger than reduced predictor size:
• generate an up-sampled reduced predictor having the current block size by applying horizontal and vertical bi-linear interpolation to the reduced predictor and selected original left reference boundary samples and selected original top reference boundary samples at specific positions;
• and
• encode or decode the current block using the up-sampled reduced predictor.

A method of video coding, the method comprising:

• receiving input data related to a current block in a current picture at a video encoder side or receiving a video bitstream comprising coded data of the current block at a video decoder side;
• determining a target reference boundary region comprising left reference boundary samples and top reference boundary samples;
• deriving a reduced predictor, wherein a process to derive the reduced predictor comprises apply matrix multiplication on a boundary vector and adding an offset, and wherein the boundary vector is derived from the target reference boundary region;
• up-sampling the reduced predictor to a same size as the current block using horizontal interpolation and vertical interpolation if the reduced predictor is smaller than the current block, wherein the horizontal interpolation and the vertical interpolation are in a fixed order regardless of a shape of the current block, size of the current block or both;
• and
• encoding or decoding the current block using the up-sampled reduced predictor.

An apparatus of video coding, the apparatus of video coding comprising one or more electronic circuits or processors arranged to:

• receive input data related to a current block in a current picture at a video encoder side or receive a video bitstream comprising coded data of the current block at a video decoder side;
• determine a target reference boundary region comprising left reference boundary samples and top reference boundary samples;
• derive a reduced predictor, wherein a process to derive the reduced predictor comprises to apply matrix multiplication on a boundary vector and to add an offset, wherein the boundary vector is derived from the target reference boundary region;
• up-sample the reduced predictor to a same size as the current block using horizontal interpolation and vertical interpolation if the reduced predictor is smaller than the current block, wherein the horizontal interpolation and the vertical interpolation are in a fixed order regardless of a shape of the current block, size of the current block or both;
• and
• encode or decode the current block using the up-sampled reduced predictor.