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EP-3939263-B1 - METHOD AND APPARATUS FOR INTRA SMOOTHING

EP3939263B1EP 3939263 B1EP3939263 B1EP 3939263B1EP-3939263-B1

Inventors

  • FILIPPOV, Alexey Konstantinovich
  • RUFITSKIY, Vasily Alexeevich
  • CHEN, JIANLE

Dates

Publication Date
20260506
Application Date
20200330

Claims (7)

  1. A method of intra prediction of a block of a picture, the method comprising: obtaining (1601) information of Intra Sub-Partitions, ISP, wherein the information of ISP indicates whether ISP is used for splitting a current block, wherein the information of ISP is indicated by a flag IntraSubPartitionsSplitType; selecting (1602) a set of coefficients of an interpolation filter based on the information of ISP, wherein the set of coefficients of the interpolation filter is fG coefficients or fC coefficients; determining interpolation filter coefficients from the set of coefficients of the interpolation filter based on an intra prediction mode of the current block; and obtaining (1603) predicted samples of the current block by applying the determined interpolation filter coefficients to reference samples; wherein the selecting (1602) the set of coefficients of the interpolation filter comprises: always determining a block filtering state is no-smoothing state when the information of ISP indicates ISP is used for splitting the current block, wherein ISP is used for splitting the current block when the value of the flag IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT; and selecting fC coefficients when the block filtering state is no-smoothing state.
  2. The method of claim 1, wherein the block filtering state is indicated by a flag smoothState, and the block filtering state is no-smoothing state when the value of smoothState is 0.
  3. The method of claim 2, wherein the value of a filter flag, filterFlag, indicates the set of coefficients of the interpolation filter is fG coefficients or fC coefficients.
  4. The method of claim 3, wherein the value of filterFlag is equal to the value of smoothState, and wherein the value of filterFlag indicates fC coefficients is selected.
  5. A decoder (30) or an encoder (20), comprising: one or more processors; and a non-transitory computer-readable storage medium coupled to the processors and storing programming for execution by the processors, wherein the programming, when executed by the processors, configures the decoder or the encoder to carry out the method according to any one of claims 1 to 4.
  6. A computer program product comprising a program code for performing the method according to any one of claims 1 to 4.
  7. A device (1800) of intra prediction of a block of a picture, the device comprising: an obtaining unit (1801), configured to obtain information of Intra Sub-Partitions, ISP, wherein the information of ISP indicates whether ISP is used for splitting a current block, wherein the information of ISP is indicated by a flag IntraSubPartitionsSplitType; a selecting unit (1802), configured to select a set of coefficients of an interpolation filter based on the information of ISP, wherein the set of coefficients of the interpolation filter is fG coefficients or fC coefficients; and a predicting unit (1803), configured to determine interpolation filter coefficients from the set of coefficients of the interpolation filter based on an intra prediction mode of the current block, and obtain predicted samples of the current block by applying the determined interpolation filter coefficients to reference samples; wherein the selecting the set of coefficients of the interpolation filter comprises: always determining a block filtering state is no-smoothing state when the information of ISP indicates ISP is used for splitting the current block, wherein ISP is used for splitting the current block when IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT; and selecting fC coefficients when the block filtering state is no-smoothing state.

Description

TECHNICAL FIELD Embodiments of the present disclosure generally relate to the field of picture processing and more particularly to intra prediction, especially to method and apparatus for intra smoothing. BACKGROUND Video coding (video encoding and decoding) is used in a wide range of digital video applications, for example broadcast digital TV, video transmission over internet and mobile networks, real-time conversational applications such as video chat, video conferencing, DVD and Blu-ray discs, video content acquisition and editing systems, and camcorders of security applications. The amount of video data needed to depict even a relatively short video can be substantial, which may result in difficulties when the data is to be streamed or otherwise communicated across a communications network with limited bandwidth capacity. Thus, video data is generally compressed before being communicated across modern day telecommunications networks. The size of a video could also be an issue when the video is stored on a storage device because memory resources may be limited. Video compression devices often use software and/or hardware at the source to code the video data prior to transmission or storage, thereby decreasing the quantity of data needed to represent digital video images. The compressed data is then received at the destination by a video decompression device that decodes the video data. With limited network resources and ever increasing demands of higher video quality, improved compression and decompression techniques that improve compression ratio with little to no sacrifice in picture quality are desirable. JVET-M1001-v7 by Bross, B. et al, "Versatile Video Coding (Draft 4)", 13. JVET Meeting, Marrakech, March 2019, provides draft text of video coding specification. JVET-M1002-v2 by Chen, J. et al, "Algorithm description for Versatile Video Coding and Test Model 4 (VTM 4), 13. JVET Meeting Marrakech, February 2019, discloses algorithm description for versatile video coding and test model 4 (VTM 4). US 2018/091825 A discloses interpolation filters for intra prediction in video coding. JVET-O0341-v1 by Lee, J. et al., "Non-CE3: Unification of intra interpolation filter selection", 15. JVET Meeting, Gothenburg, June 2019, discloses interpolation filters for intra interpolation filter selection. SUMMARY Embodiments of the present disclosure provide apparatuses and methods for encoding and decoding according to the independent claims. The present invention is defined according to the independent claims. The dependent claims recite advantageous embodiments of the invention. Further implementation forms are apparent from the dependent claims, the description and the figures. In the following, parts of the description and drawings referring to embodiments which are not covered by the claims are not presented as embodiments of the invention, but as examples useful for understanding the invention. A first aspect of the invention relates to a method of intra prediction of a block of a picture. The method includes: obtaining information of Intra Sub-Partitions, ISP, wherein the information of ISP indicates whether ISP is used for splitting a current block, wherein the information of ISP is indicated by a flag IntraSubPartitionsSplitType; selecting a set of coefficients of an interpolation filter based on the information of ISP, wherein the set of coefficients of the interpolation filter is fG coefficients or fC coefficients; determining interpolation filter coefficients from the set of coefficients of the interpolation filter based on an intra prediction mode of the current block; and obtaining predicted samples of the current block by applying the determined interpolation filter coefficients to reference samples;wherein the selecting the set of coefficients of the interpolation filter comprises: always determining a block filtering state is no-smoothing state when the information of ISP indicates ISP is used for splitting the current block, wherein ISP is used for splitting the current block when the value of the flag IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT; and selecting fC coefficients when the block filtering state is no-smoothing state. A second aspect of an example not being part of the present invention but useful for understanding the present invention relates to a method of intra prediction of a block of a picture. The method includes: detecting a block filtering state (i.e., smoothing state of the block) based on information of Intra Sub-Partitions (ISP), wherein the block filtering state includes no-smoothing state, smoothing state, or direction-dependent smoothing state; and selecting a set of coefficients of an interpolation filter based on the value of the block filtering state, wherein the set of coefficients of the interpolation filter is fG coefficients or fC coefficients. The method further includes obtaining predicted samples of the current block by applying the set of coefficie