Methods and apparatus of video coding using prediction refinement with optical flow

Abstract

An electronic apparatus performs a method of updating an inter-predicted current block using a neighboring affine block. The electronic apparatus first identifies a pixel within the inter-predicted current block, the pixel having a first inter-predicted pixel value. Next, the electronic apparatus determines a motion vector difference for the pixel based on a set of affine parameters of the neighboring affine block and then a pixel value difference for the pixel according to the motion vector difference. The pixel value difference is an inner product of the pixel value gradient vector and the motion vector difference as the pixel value difference. Finally, the electronic apparatus updates the first inter-predicted pixel value with the pixel value difference as a second inter-predicted pixel value.