# US 2025/0097431 A1 · Image encoding/decoding method and apparatus with sub-block intra prediction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0097431 A1 - Document ID: US20250097431A1 - Status: Published application - Kind: A1 - Application number: 18/910,820 - Filed: 2024-10-09 - Published: 2025-03-20 - Earliest claimed: 2016-08-01 - Assignees: Electronics and Telecommunications Research Institute - Applicants: Electronics and Telecommunications Research Institute - Inventors: Dong San JUN; Jin Ho LEE; Jung Won KANG; Hyun Suk KO; Sung Chang LIM; Ha Hyun LEE; Seung Hyun CHO; Hui Yong KIM; Jin Soo CHOI - Web page: https://patentgrep.com/patent/US20250097431A1 ## CPC - H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction - 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 19/126: Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers - H04N 19/13: Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC] - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/50: using predictive coding (H04N19/61 takes precedence) - H04N 19/593: involving spatial prediction techniques - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image encoding/decoding method and apparatus for performing intra prediction are provided. An image decoding method of the present invention comprises deriving an intra prediction mode for a current block, selecting at least one reconstructed sample line neighboring to the current block, constructing a reference sample using at least one reconstructed sample included in the at least one reconstructed sample line, and performing intra prediction for the current block based on the intra prediction mode and the reference sample. ## Claims ### Claim 1 An image decoding method, comprising: deriving an intra prediction mode of a current block; determining a search range of reference samples for an intra prediction of the current block; determining the reference samples for the intra prediction of the current block among the search range of the reference samples; and generating a prediction block by performing the intra prediction for the current block based on the intra prediction mode and the reference samples, wherein a predetermined number of the reference samples are non-adjacent reference samples that are apart from each other by a predetermined sample unit among the search range, wherein the current block is obtained by dividing a coding tree block based on a division information signaled from a bitstream, and wherein the division information includes a division flag indicates whether to divide the coding tree block. ### Claim 2 (depends on 1) The method of claim 1, wherein the search range is determined based on the intra prediction mode of the current block and a size of the current block. ### Claim 3 (depends on 1) The method of claim 1, wherein the reference samples are determined by shifting the predetermined sample unit only for a left reference sample or an upper reference sample of the current block. ### Claim 4 An image encoding method, comprising: deriving an intra prediction mode of a current block; determining a search range of reference samples for an intra prediction of the current block; determining the reference samples for the intra prediction of the current block among the search range of the reference samples; and generating a prediction block by performing the intra prediction for the current block based on the intra prediction mode and the reference samples, wherein a predetermined number of the reference samples are non-adjacent reference samples that are apart from each other by a predetermined sample unit among the search range, wherein the current block is obtained by dividing a coding tree block, wherein division information includes a division flag indicates whether to divide the coding tree block, and wherein the division information is encoded into a bitstream. ### Claim 5 (depends on 4) The method of claim 4, wherein the search range is determined based on the intra prediction mode of the current block and a size of the current block. ### Claim 6 (depends on 4) The method of claim 4, wherein the reference samples are determined by shifting the predetermined sample unit only for a left reference sample or an upper reference sample of the current block. ### Claim 7 A non-transitory computer-readable storage medium storing a bitstream generated by a method of encoding a video, the method comprising: deriving an intra prediction mode of a current block; determining a search range of reference samples for an intra prediction of the current block; determining the reference samples for the intra prediction of the current block among the search range of the reference samples; and generating a prediction block by performing the intra prediction for the current block based on the intra prediction mode and the reference samples, wherein a predetermined number of the reference samples are non-adjacent reference samples that are apart from each other by a predetermined sample unit among the search range, wherein the current block is obtained by dividing a coding tree block, wherein division information includes a division flag indicates whether to divide the coding tree block, and wherein the division information is encoded into the bitstream.