# US 12,120,289 B2 · Image encoding/decoding method and device for performing prediction on basis of HMVP candidate, and method for transmitting bitstream > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,120,289 B2 - Document ID: US12120289B2 - Status: Granted - Kind: B2 - Application number: 17/636,911 - Filed: 2020-08-20 - Published: 2022-09-01 - Granted: 2024-10-15 - Earliest claimed: 2019-08-21 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Nae Ri Park; Jung Hak Nam; Hyeong Moon Jang - Web page: https://patentgrep.com/patent/US12120289B2 ## CPC - 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 19/52: by predictive encoding - H04N 19/11: among a plurality of spatial predictive coding modes - H04N 19/119: Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks - H04N 19/137: Motion inside a coding unit, e.g. average field, frame or block difference - H04N 19/14: Coding unit complexity, e.g. amount of activity or edge presence estimation (H04N19/146 takes precedence) - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/423: characterised by memory arrangements (H04N19/433 takes precedence) - H04N 19/513: Processing of motion vectors - H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image encoding/decoding method and apparatus are provided. An image decoding method according to the present disclosure is performed by an image decoding apparatus. The image decoding method comprises deriving a prediction mode of a current block, constructing a merge candidate list for the current block, based on the prediction mode of the current block being a triangle partition mode (TPM), deriving motion information of two partitions of the current block based on the merge candidate list and two merge indices of the current block signaled through a bitstream, generating a prediction block of the current block based on the motion information, storing motion information of the current block, and updating a history-based motion vector predictor (HMVP) buffer based on the motion information of the current block. ## Claims ### Claim 1 An image decoding method performed by an image decoding apparatus, the image decoding method comprising: deriving a prediction mode of a current block; constructing a merge candidate list for the current block, based on the prediction mode of the current block being a triangle partition mode (TPM); deriving motion information of two partitions of the current block based on the merge candidate list and two merge indices of the current block signaled through a bitstream; generating a prediction block of the current block based on the motion information; storing motion information of the current block; and updating a history-based motion vector predictor (HMVP) buffer based on the motion information of the current block, wherein the updating the HMVP buffer is performed based on motion information of a 4×4 sample unit at a predetermined position in the current block, and wherein, based on a width and height of the current block being respectively cbWidth and cbHeight, the predetermined position is derived as (cbWidth>>1, cbHeight>>1) based on a partition direction is diagonal partition and is derived as (cbWidth>>1−1, cbHeight>>1) based on a partition direction is inverse diagonal partition. ### Claim 2 (depends on 1) The image decoding method of claim 1, wherein the merge candidate list comprises an HMVP candidate. ### Claim 3 (depends on 1) The image decoding method of claim 1, wherein the storing the motion information of the current block comprises storing the motion information in units of 4×4 samples in the current block. ### Claim 4 (depends on 1) The image decoding method of claim 1, wherein the predetermined position is one of a center position, a top-left position or a bottom-right position in the current block. ### Claim 5 (depends on 1) The image decoding method of claim 1, wherein the predetermined position is derived regardless of a partition direction of the triangle partition mode. ### Claim 6 (depends on 1) The image decoding method of claim 1, wherein the motion information of the two partitions comprises first motion information and second motion information, and wherein the updating the HMVP buffer is performed based on one of the first motion information or the second motion information. ### Claim 7 (depends on 6) The image decoding method of claim 6, comprising selecting one of the first motion information or the second motion information based on a partition direction of the triangle partition mode and updating the HMVP buffer based on the selected motion information. ### Claim 8 (depends on 6) The image decoding method of claim 6, comprising updating the HMVP buffer based on one predefined motion information of the first motion information or the second motion information regardless of a partition direction of the triangle partition mode. ### Claim 9 (depends on 1) The image decoding method of claim 1, wherein the motion information used to update the HMVP buffer comprises a motion vector, a reference picture index, a prediction direction flag and a weight index of bcw set to 0. ### Claim 10 An image encoding method performed by an image encoding apparatus, the image encoding method comprising: determining a prediction mode of a current block; constructing a merge candidate list for the current block, based on the prediction mode of the current block being a triangle partition mode (TPM); determining a merge candidate for two partitions of the current block based on the merge candidate list; deriving motion information of the two partitions of the current block based on the determined merge candidate; generating a prediction block of the current block based on the motion information; storing motion information of the current block; updating a history-based motion vector predictor (HMVP) buffer based on the motion information of the current block; and encoding a merge index specifying the determined merge candidate in a bitstream, wherein the updating the HMVP buffer is performed based on motion information of a 4×4 sample unit at a predetermined position in the current block, and wherein, based on a width and height of the current block being respectively cbWidth and cbHeight, the predetermined position is derived as (cbWidth>>1, cbHeight>>1) based on a partition direction is diagonal partition and is derived as (cbWidth>>1−1, cbHeight>>1) based on a partition direction is inverse diagonal partition. ### Claim 11 (depends on 10) A method of transmitting a bitstream generated by the image encoding method of claim 10.