# US 2020/0404282 A1 · Lic signaling methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0404282 A1 - Document ID: US20200404282A1 - Status: Published application - Kind: A1 - Application number: 16/894,051 - Filed: 2020-06-05 - Published: 2020-12-24 - Earliest claimed: 2019-06-20 - Assignees: Tencent America LLC - Applicants: Tencent America LLC - Inventors: Guichun LI; Xiaozhong Xu; Xiang Li; Shan Liu - Web page: https://patentgrep.com/patent/US20200404282A1 ## CPC - H04N 19/136: Incoming video signal characteristics or properties - H04N 19/54: using feature points or meshes - H04N 19/105: Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction - H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) - H04N 19/132: Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking - H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/186: the unit being a colour or a chrominance component - H04N 19/46: Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) - H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A method may include: receiving information regarding a current data block of an image; determining whether Local Illumination Compensation (LIC) is applicable for the current data block; based on determining that the LIC is applicable for the current data block, at least one of: infering an LIC flag for the current data block to be 1 or true corresponding to the LIC being enabled, or inheriting the current block's LIC flag from an LIC flag of a neighboring block; and based on the LIC flag for the current data block corresponding to the LIC being enabled, generate a prediction of at least one sub-block with a derived motion vector by applying LIC to the current data block using the inherited LIC flag. ## Claims ### Claim 1 A method comprising: receiving information regarding a current data block of an image; determining whether Local Illumination Compensation (LIC) is applicable for the current data block, wherein the determining of whether LIC is applicable for the current block includes determining whether the current data block is coded with affine inter prediction; based on determining that the LIC is applicable for the current data block, at least one of: infering an LIC flag for the current data block to be 1 or true corresponding to the LIC being enabled, or inheriting the current block's LIC flag from an LIC flag of a neighboring block; and based on the LIC flag for the current data block corresponding to the LIC being enabled, generating a prediction of at least one sub-block with a derived motion vector by applying LIC to the current data block using the inherited LIC flag. ### Claim 2 (depends on 1) The method of claim 1, wherein the determining of whether the LIC is applicable for the current data block includes: determining whether the current data block is coded with affine inter prediction or regular inter prediction; and based on determining that the current block is coded with affine inter prediction: determining whether any other LIC resrictions apply; and based on determining that no other LIC restrictions apply, infer that the LIC is enabled. ### Claim 3 (depends on 2) The method of claim 2, wherein the applying of the LIC to the current data block includes, if the current block is using a constructed affine merge mode, inheriting the current block's LIC flag from the LIC flag of the neighboring block. ### Claim 4 (depends on 1) The method of claim 1, wherein the neighboring block is used to predict a control point motion vector of a corner of the current data block. ### Claim 5 (depends on 4) The method of claim 4, wherein the predicted control point motion vector of the corner of the current data block is a predicted control point motion vector of a top-left corner of the current data block. ### Claim 6 (depends on 1) The method of claim 1, wherein applying the LIC to the current data block includes: applying LIC for an affine data block based on a linear model for illumination changes, using a scaling factor and an offset based on the derived motion vector, and, for each prediction direction, deriving the scaling factor and the offset by using at least one neighbouring sample of the current block and at least one corresponding reference sample. ### Claim 7 (depends on 6) The method of claim 6, wherein the at least one neighboring sample includes subsampled neighbouring samples of the current block and corresponding reference samples identified by motion information of the current block in a reference picture. ### Claim 8 (depends on 1) The method of claim 1, further comprising: when the current data block is coded with merge mode, copying the LIC flag from neighbouring blocks, in a way similar to motion information copied in the merge mode; and when the current data block is not coded with merge mode, the LIC flag is signalled for the current data block to indicate whether LIC applies or not. ### Claim 9 (depends on 1) The method of claim 1, wherein the applying of the LIC includes using a mean-removed sum of absolute difference (MR-SAD) and a mean-removed sum of absolute Hadamard-transformed difference (MR-SATD) instead of SAD and SATD, for integer pel motion search and fractional pel motion search, respectively. ### Claim 10 (depends on 1) The method of claim 1, wherein the applying of the LIC includes uni-directional illumination compensation, and in local illumination compensation, the scaling factor and offset are derived and the LIC is applied on a CU basis. ### Claim 11 (depends on 2) The method of claim 2, wherein the other restrictions include: a sub-block based on TMVP, triangular partition, multi hypothesis intra inter and bi-directional prediction, or bi-directional prediction. ### Claim 12 (depends on 2) The method of claim 2, wherein the other restrictions include: when one or more of the following conditions apply: (A) when the number of samples in the current block is below a certain minimum threshold; (B) when the number of samples in the current block is above a certain maximum threshold; (C) when the number of samples on either side of the current block is below a side minimum threshold; or (D) when the number of samples in either side of the current block is above a certain maximum threshold. ### Claim 13 (depends on 12) The method of claim 12, wherein the certain minimum threshold, certain maximum threshold, the certain side minimum threshold and the certain maximum threshold vary based on whether the current data block is an affine inter prediction data block. ### Claim 14 (depends on 12) The method of claim 12, wherein at least one of: the minimum threshold is set to 64 luma samples, the maximum threshold is set to 4096 luma samples, the side minimum threshold is set to 8 luma samples, or the side maximum threshold is set to 64 luma samples. ### Claim 15 (depends on 2) The method of claim 2, wherein the other restrictions include at least one of: an LIC flag is not stored in the motion vector buffer of the reference picture, or a bi-directional merge candidate, a par-wise average candidate, or a zero motion candidate is used. ### Claim 16 (depends on 1) The method of claim 1, further comprising: when the current data block is coded with affine inter prediction affine merge mode, determining the LIC flag value for the current data block by inheriting the LIC flag of a neighboring block that is used as a source of affine model inheritance, which is signalled in the bitstream to indicate whether affine AMVP mode is used, and another flag signals to indicate whether 4-parameter affine or 6-parameter affine is used, and use a first equation when 4-parameter affine is used, and use a second equation when 6-parameter affine is used. ### Claim 17 (depends on 1) The method of claim 1, wherein the inferred LIC flag is enabled for either affine AMVP mode or AMVP mode for regular inter prediction, but not for both. ### Claim 18 (depends on 1) The method of claim 1, further comprising: applying affine merge mode for CUs with both width and height larger than or equal to a threshold, and selecting only a first inherited candidate from each side, and when a neighboring affine CU is identified, control point motion vectors of the neighboring affine CU are used to derive the CPMVP candidate in the affine merge list of the current CU. ### Claim 19 An apparatus comprising: at least one memory configured to store computer program code; and at least one processor configured to access the at least one memory and operate according to the computer program code, the computer program code comprising: first applying code configured to cause the at least one processor to receive information regarding a current data block of an image; second applying code configured to cause the at least one processor to determine whether Local Illumination Compensation (LIC) is applicable for the current data block, wherein the determining of whether LIC is applicable for the current block includes determining whether the current data block is coded with affine inter prediction; third applying code configured to cause the at least one processor to, based on determining that the LIC is applicable for the current data block, at least one of: infer an LIC flag for the current data block to be 1 or true corresponding to the LIC being enabled, or inherit the current block's LIC flag from an LIC flag of a neighboring block; and fourth applying code configured to cause the at least one processor to, based on the LIC flag for the current data block corresponding to the LIC being enabled, generate a prediction of at least one sub-block with a derived motion vector by applying LIC to the current data block using the inherited LIC flag. ### Claim 20 A non-transitory computer-readable storage medium storing instructions that cause one or more processors to: receive information regarding a current data block of an image; determine whether Local Illumination Compensation (LIC) is applicable for the current data block, wherein the determining of whether LIC is applicable for the current block includes determining whether the current data block is coded with affine inter prediction; based on determining that the LIC is applicable for the current data block, at least one of: infer an LIC flag for the current data block to be 1 or true corresponding to the LIC being enabled, or inherit the current block's LIC flag from an LIC flag of a neighboring block; and based on the LIC flag for the current data block corresponding to the LIC being enabled, generate a prediction of at least one sub-block with a derived motion vector by applying LIC to the current data block using the inherited LIC flag.