# US 11,445,185 B2 · Image encoding/decoding method and device, and recording medium in which bitstream is stored > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,445,185 B2 - Document ID: US11445185B2 - Status: Granted - Kind: B2 - Application number: 17/277,597 - Filed: 2019-09-18 - Published: 2022-01-27 - Granted: 2022-09-13 - Earliest claimed: 2018-09-19 - Assignees: Electronics and Telecommunications Research Institute - Applicants: Electronics and Telecommunications Research Institute - Inventors: Jin Ho Lee; Jung Won Kang; Ha Hyun Lee; Sung Chang Lim; Hui Yong Kim - Web page: https://patentgrep.com/patent/US11445185B2 ## CPC - H04N 19/11: among a plurality of spatial predictive coding modes - 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 19/176: the region being a block, e.g. a macroblock - H04N 19/186: the unit being a colour or a chrominance component - H04N 19/593: involving spatial prediction techniques - H04N 19/119: Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks - H04N 19/129: Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO] - 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 19/184: the unit being bits, e.g. of the compressed video stream - H04N 19/577: Motion compensation with bidirectional frame interpolation, i.e. using B-pictures - H04N 19/597: specially adapted for multi-view video sequence encoding - H04N 19/96: Tree coding, e.g. quad-tree coding - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image encoding/decoding method is disclosed. An image decoding method of the present invention may comprise deriving an intra-prediction mode of a current block by using an intra-prediction mode of a neighbor block adjacent to the current block, configuring a reference sample of the current block, and performing intra-prediction on the current block by using the intra-prediction mode and the reference sample, wherein when the intra-prediction mode of the neighbor block is unavailable, the intra-prediction mode of the neighbor block may be replaced with a planar mode. ## Claims ### Claim 1 An image decoding method performed by an image decoding apparatus, the image decoding method comprising: deriving an intra prediction mode of a current block using an intra prediction mode of a neighboring block adjacent to the current block; selecting one reference sample line from among a plurality of reference sample lines adjacent to the current block; generating reference samples for the current block based on the selected one reference sample line; and performing intra prediction for the current block using the intra prediction mode and the reference samples, wherein the performing intra prediction for the current block comprises, selecting an interpolation filter from among a plurality of interpolation filters; and filtering the reference samples using the selected interpolation filter, wherein the interpolation filter is selected based on a size of the current block, and wherein the size of the current block is derived based on an average of a log value of width of the current block and a log value of a height of the current block. ### Claim 2 (depends on 1) The image decoding method of claim 1, wherein the selecting one interpolation filter from among the plurality of interpolation filters and the filtering the reference samples using the selected interpolation filter is performed in case the intra prediction mode of the current block is a directional mode. ### Claim 3 (depends on 1) The image decoding method of claim 1, wherein, in case the selected one reference sample line is a first reference sample line directly adjacent to the current block, the selecting one interpolation filter from among the plurality of interpolation filters is performed based on the size of the current block. ### Claim 4 (depends on 1) The image decoding method of claim 1, wherein, in case the selected one reference sample line is not a first reference sample line directly adjacent to the current block, a cubic filter is selected as the interpolation filter for filtering the reference samples. ### Claim 5 (depends on 1) The image decoding method of claim 1, further comprising: determining whether to perform a secondary filtering for the prediction block of the current block based on at least one among the intra prediction mode of the current block, a size of the current block or the selected one reference sample line; deriving a scaling value based on the size of the current block in case the secondary filtering is performed; deriving a filter coefficient of the secondary filtering based on the scaling value; and generating a filtered prediction block of the current block by performing the secondary filtering for the prediction block based on the derived filter coefficient. ### Claim 6 An image encoding method performed by an image encoding apparatus, the image encoding method comprising: determining an intra prediction mode of a current block; selecting one reference sample line from among a plurality of reference sample lines adjacent to the current block; generating reference samples for the current block based on the selected one reference sample line; performing intra prediction for the current block using the intra prediction mode and the reference samples; and encoding the intra prediction mode of the current block using an intra prediction mode of a neighboring block adjacent to the current block, wherein the performing intra prediction for the current block comprises, selecting an interpolation filter from among a plurality of interpolation filters; and filtering the reference samples using the selected interpolation filter, wherein the interpolation filter is selected based on a size of the current block, and wherein the size of the current block is derived based on an average of a log value of width of the current block and a log value of a height of the current block. ### Claim 7 (depends on 6) The image encoding method of claim 6, wherein the selecting one interpolation filter from among the plurality of interpolation filters and the filtering the reference samples using the selected interpolation filter is performed in case the intra prediction mode of the current block is a directional mode. ### Claim 8 (depends on 6) The image encoding method of claim 6, wherein, in case the selected one reference sample line is a first reference sample line directly adjacent to the current block, the selecting one interpolation filter from among the plurality of interpolation filters is performed based on the size of the current block. ### Claim 9 (depends on 6) The image encoding method of claim 6, wherein, in case the selected one reference sample line is not a first reference sample line directly adjacent to the current block, a cubic filter is selected as the interpolation filter for filtering the reference samples. ### Claim 10 A non-transitory computer readable recording medium storing a bitstream that is generated by an image encoding method, the image encoding method comprising: determining an intra prediction mode of a current block; selecting one reference sample line from among a plurality of reference sample lines adjacent to the current block; generating reference samples for the current block based on the selected one reference sample line; performing intra prediction for the current block using the intra prediction mode and the reference samples; and encoding the intra prediction mode of the current block using an intra prediction mode of a neighboring block adjacent to the current block, wherein the performing intra prediction for the current block comprises, selecting an interpolation filter from among a plurality of interpolation filters; and filtering the reference samples using the selected interpolation filter, wherein the interpolation filter is selected based on a size of the current block, and wherein the size of the current block is derived based on an average of a log value of width of the current block and a log value of a height of the current block.