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.

This disclosure signaling of motion vector or motion vector difference dependent on whether magnitude-dependent adaptive motion vector difference pixel resolution is employed or not in video encoding and decoding. An example method for processing a video block of a video stream is disclosed. The method may include receiving the video stream; determining that the video block is inter-coded based on a prediction block and a motion vector (MV), wherein the MV is to be derived from a reference motion vector (RMV) and a motion vector difference (MVD) for the video block; extracting or deriving, from the video stream, a data item associated with at least one of the RMV or the MVD, in a manner depending at least on whether the MVD is coded with magnitude-dependent adaptive MVD pixel resolution; extracting the MVD from the video stream; deriving the MV based on the extracted RMV and the MVD; and reconstructing the video block based at least on the MV and the prediction block

This disclosure relates to encoding and decoding of motion vector difference for inter-predicting a video block. An example is disclosed for decoding an inter-predicted video block of a video stream. The method may include determining that a motion vector associated with the inter-predicted video block is encoded as a motion vector difference (MVD) between the motion vector and a reference motion vector; obtaining, from the video stream, an indication of a magnitude range of the MVD among a plurality of predefined magnitude ranges for motion vector differences; determining a pixel resolution for the MVD according to the magnitude range; identifying additional MVD information in the video stream based on the pixel resolution; extracting the additional MVD information from the video stream; and decoding the inter-predicted video block based on the pixel resolution, the additional MVD information, the reference motion vector, and a reference frame associated with the motion vector.

The present disclosure relates to a method and apparatus for improving the encoding efficiency by adaptively changing the resolution of the motion vector in the inter prediction encoding and inter prediction decoding of a video. The apparatus includes: a predicted motion vector calculator for calculating a predicted motion vector of a current block to be encoded using motion vectors of one or more surrounding blocks; and a skip mode encoder for encoding a result of performing a prediction of the current block and information indicating that the current block is a skip block when the predicted motion vector satisfies a skip condition, wherein at least one motion vector among the motion vectors of the surrounding blocks and the motion vector of the current block has a resolution different from resolutions of the other motion vectors.

The present disclosure relates to a method and apparatus for improving the encoding efficiency by adaptively changing the resolution of the motion vector in the inter prediction encoding and inter prediction decoding of a video. The apparatus includes: a predicted motion vector calculator for calculating a predicted motion vector of a current block to be encoded using motion vectors of one or more surrounding blocks; and a skip mode encoder for encoding a result of performing a prediction of the current block and information indicating that the current block is a skip block when the predicted motion vector satisfies a skip condition, wherein at least one motion vector among the motion vectors of the surrounding blocks and the motion vector of the current block has a resolution different from resolutions of the other motion vectors.

Approaches to selection of motion vector (“MV”) precision during video encoding are presented. These approaches can facilitate compression that is effective in terms of rate-distortion performance and/or computational efficiency. For example, a video encoder determines an MV precision for a unit of video from among multiple MV precisions, which include one or more fractional-sample MV precisions and integer-sample MV precision. The video encoder can identify a set of MV values having a fractional-sample MV precision, then select the MV precision for the unit based at least in part on prevalence of MV values (within the set) having a fractional part of zero. Or, the video encoder can perform rate-distortion analysis, where the rate-distortion analysis is biased towards the integer-sample MV precision. Or, the video encoder can collect information about the video and select the MV precision for the unit based at least in part on the collected information.

Approaches to selection of motion vector (“MV”) precision during video encoding are presented. These approaches can facilitate compression that is effective in terms of rate-distortion performance and/or computational efficiency. For example, a video encoder determines an MV precision for a unit of video from among multiple MV precisions, which include one or more fractional-sample MV precisions and integer-sample MV precision. The video encoder can identify a set of MV values having a fractional-sample MV precision, then select the MV precision for the unit based at least in part on prevalence of MV values (within the set) having a fractional part of zero. Or, the video encoder can perform rate-distortion analysis, where the rate-distortion analysis is biased towards the integer-sample MV precision. Or, the video encoder can collect information about the video and select the MV precision for the unit based at least in part on the collected information.

The present invention is related to processing a video signal. A method for decoding a video according to the present invention may comprise checking a merge coding unit which is generated by merging a plurality of coding units neighboring each other based on an encoded syntax element, and decoding the checked merge coding unit, wherein a same motion vector is shared in the merge coding unit.

The present disclosure provides systems and methods for video coding. The systems include, for example, an image encoder comprising: circuitry; and a memory coupled to the circuitry, wherein the circuitry, in operation, performs the following: predicting a first block of prediction samples for a current block of a picture, wherein predicting the first block of prediction samples includes at least a prediction process with a motion vector from a different picture; padding the first block of prediction samples to form a second block of prediction samples, wherein the second block is larger than the first block; calculating at least a gradient using the second block of prediction samples; and encoding the current block using at least the calculated gradient.

Aspects of the disclosure provide methods and apparatuses for video decoding. In some examples, an apparatus includes processing circuitry. The processing circuitry decodes prediction information of a current block from a coded video bitstream. Based on an intra block copy mode being applied to the current block, the processing circuitry infers a vector resolution flag indicates that a resolution of a block vector is integer-pel, determines the resolution of the block vector based on resolution information that is included in the prediction information, determines the block vector according to the determined resolution, and reconstructs at least one sample of the current block according the block vector.