Abstract: Given that decoder side motion vector refinement/derivation is a normative aspect of a coding system, the encoder will also have to perform the same error surface technique in order to not have any drift between the encoder's reconstruction and the decoder's reconstruction. Hence, all aspects of all embodiments are applicable to both encoding and decoding systems. In template matching, the refinement movement occurs only in the reference starting from the sub-pixel accurate center that is derived based on the explicitly signaled merge index or implicitly through cost evaluations. In bilateral matching (with or without averaged template), the refinements start in the reference lists L0 and L1 starting from the respective sub-pixel accurate centers that are derived based on the explicitly signaled merge index or implicitly through cost evaluations.

Abstract: An image prediction method and apparatus includes obtaining predicted motion information of an image block; determining an initial predicted block of the image block according to the predicted motion information and a reference image of the image block; performing, according to the predicted motion information, L iterative searches in the reference image using an integer pixel step size to obtain an intermediate predicted block of the image block; performing a single search in the reference image using a fractional pixel step size to obtain M predicted blocks of the image block; determining a target predicted block of the image block according to the M predicted blocks and the intermediate predicted block; and obtaining a predicted value of a pixel value of the image block according to a pixel value of the target predicted block.