Disclosed is an image encoding method. The method includes deriving a motion refinement candidate from among motion information of spatial neighboring blocks, motion information of a temporal neighboring blocks, predefined motion information, and motion information that most frequently occurs in a reference picture, performing a motion information refinement on the derived motion refinement candidate, and generating a prediction block of a current block by using the motion refinement candidate having undergone the motion information refinement.

Methods, systems and device for hash-based motion estimation in video coding are described. An exemplary method of video processing includes determining, for a conversion between a current block of a video and a bitstream representation of the video, motion information associated with the current block using a hash-based motion search, a size of the current block being M×N, M and N being positive integers and M being not equal to N, applying, based on the motion information and a video picture comprising the current block, a prediction for the current block, and performing, based on the prediction, the conversion.

A format for use in encoding moving image data, comprising: a sequence of frames including plurality of the frames in which at least a region is encoded using motion estimation; a respective set of motion vector values representing motion vectors of the motion estimation for each respective one of these frames or each respective one of one or more regions within each of such frames; and at least one respective indicator associated with each of the respective frames or regions, indicating whether the respective motion vector values of the respective frame or region are encoded at a first resolution or a second resolution.

A format for use in encoding moving image data, comprising: a sequence of frames including plurality of the frames in which at least a region is encoded using motion estimation; a respective set of motion vector values representing motion vectors of the motion estimation for each respective one of these frames or each respective one of one or more regions within each of such frames; and at least one respective indicator associated with each of the respective frames or regions, indicating whether the respective motion vector values of the respective frame or region are encoded at a first resolution or a second resolution.

Methods and system, including decoders and encoders, for interprediction. In one aspect, a method includes selecting reference samples based on motion information of a current picture block of a current picture, deriving first interpolated samples by performing a first interpolation on the selected reference samples, deriving an integer distance delta motion vector for a target sub-prediction unit (PU) by performing integer-distance MVR, deriving M×M pixel matrix flow vectors by performing BPOF, for each M×M pixel matrix in the target sub-PU, based on the first interpolated samples and the integer distance delta motion vector, deriving second interpolated samples by performing a second interpolation on the reference samples, computing at least one correction parameter for the target sub-PU based on the M×M pixel matrix flow vectors, the first interpolated samples and the second interpolated samples, and performing bi-prediction based on the second interpolated samples and the at least one correction parameter.

This disclosure relates generally to video coding and particularly to methods and systems for providing signaling schemes for motion vector difference. An example method for decoding a current video block of a video bitstream is disclosed. The method includes receiving a coded video bitstream; obtaining, from the coded video bitstream, a first motion vector difference (MVD) and a dynamic reference list (DRL) index for a current video block; deriving a second MVD for the current video block based on the first MVD; generating, by the device, a motion vector (MV) pair based on the first MVD, the derived second MVD, and a motion vector predictor (MVP) indicated by the DRL index; and decoding, by the device based on the MV pair, the current video block.

A method for video decoding includes decoding prediction information of a current block, the prediction information being indicative of a symmetric motion vector difference mode for bi-prediction from a pair of forward and backward reference pictures. The method also includes assigning, to a reference picture marked as a long term reference picture (LTRP), a calculated picture order count with a default POC distance to the current picture, and excluding a reference picture from being in the pair of forward and backward reference pictures without a check based on a picture order count (POC) of the reference picture. The method further includes determining a first reference block for the current block in the forward reference picture and a second reference block for the current block in the backward reference picture, and reconstructing at least a sample of the current block according to the first reference block and the second reference block.

Aspects of the disclosure provide a method and an apparatus for video coding. In some examples, the apparatus includes processing circuitry. The processing circuitry decodes prediction information of a current block in a current picture from a coded video bitstream and the prediction information is indicative of inter prediction. The processing circuitry determines, for the current block, motion information including a first motion vector (MV) that has a x component and a y component where each of the x and y components has a fractional MV precision that is 2.sup.−N of a sample size in the current block and has one of 2.sup.L+1 MV values with the fractional MV precision. N is an integer larger than 2 and L is a positive integer. The processing circuitry reconstructs at least one sample of the current block based on the motion information.

Video signal coding and decoding functions can generate lists of potential candidates to use in coding and decoding, for example, predictors. Video signal coding component candidate undergo operations before potential inclusion in candidate lists. The candidates are checked after being modified by the operations to see if other equal candidates are already in the candidate list. If equal candidates are not in the list, the modified candidates are added to the candidate list. If equal candidates are already in the list, the modified candidates are not added to the list. Operations that can be performed comprise rounding and clipping.

A method of generating three dimensional shapes for a cornea and lens of an eye, the method including illuminating an eye with multiple sections of light and obtaining multiple sectional images of said eye based on said multiple sections of light. For each one of the obtained multiple sectional images, the following processes are performed: a) automatically identifying arcs, in two-dimensional space, corresponding to anterior and posterior corneal and lens surfaces of the eye by image analysis and curve fitting of the one of the obtained multiple sectional images; and b) determining an intersection of lines ray traced back from the identified arcs in two-dimensional space with a known position of a section of space containing the section of light that generated the one of the obtained multiple sectional images, wherein the determined intersection defines a three-dimensional arc curve. The method further including reconstructing three-dimensional shapes of the anterior and posterior cornea surfaces and the anterior and posterior lens surfaces based on fitting the three-dimensional arc curve to a three-dimensional shape.