# US 12,113,973 B2 · Adaptive loop filtering-based image coding apparatus and method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,113,973 B2 - Document ID: US12113973B2 - Status: Granted - Kind: B2 - Application number: 17/792,600 - Filed: 2021-01-15 - Published: 2023-03-09 - Granted: 2024-10-08 - Earliest claimed: 2020-01-15 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Seethal Paluri; Hendry Hendry - Web page: https://patentgrep.com/patent/US12113973B2 ## CPC - H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) - G06V 10/60: relating to illumination properties, e.g. using a reflectance or lighting model - 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 19/172: the region being a picture, frame or field - H04N 19/186: the unit being a colour or a chrominance component - H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards - H04N 19/82: involving filtering within a prediction loop - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING ## Abstract According to embodiment(s) of the present document, computational overhead and complexity can be reduced by using a 0th-order exponential Golomb coding scheme (ue(v)) for procedures of parsing syntax elements/information about absolute values of luma/chroma ALF filter coefficients. In addition, coding using ue(v) can be efficiently performed by fixing the range of values of the information about the absolute values of the luma/chroma ALF filter coefficients. ## Claims ### Claim 1 An image decoding method performed by a decoding apparatus, the method comprising: receiving image information through a bitstream; generating reconstructed samples based on the image information; deriving ALF data for an adaptive loop filter (ALF) procedure of the reconstructed samples; and performing the ALF procedure of the reconstructed samples based on the ALF data, wherein the performing the ALF procedure comprises: deriving absolute values of luma filter coefficients for the ALF procedure based on the ALF data; deriving luma filter coefficients for the ALF procedure based on the absolute values of luma filter coefficients for the ALF procedure; and generating modified luma reconstructed samples based on the reconstructed samples and the luma filter coefficients, wherein the ALF data includes information related to absolute values of luma filter coefficients for the ALF procedure, and wherein the information related to absolute values of luma filter coefficients for the ALF procedure is coded based on ue(v). ### Claim 2 (depends on 1) The image decoding method of claim 1, wherein the image information includes parameter sets, wherein at least one of the parameter sets includes an adaptation parameter set (APS), and wherein the ALF data is included in the APS. ### Claim 3 (depends on 1) The image decoding method of claim 1, wherein the image information includes header information and ALF-related adaptation parameter set (APS), wherein the header information includes information related to a number of ALF-related APS IDs, wherein the number of ALF-related APS IDs is derived based on a value of information related to the number of ALF-related APS IDs, and wherein a number of ALF-related APS ID syntax elements equal to the number of ALF-related APS IDs is included in the header information. ### Claim 4 (depends on 1) The image decoding method of claim 1, wherein the image information includes header information and an ALF-related adaptation parameter set (APS), wherein the header information includes an ALF availability flag indicating whether or not the ALF is available for usage within a picture or slice and information related to a number of ALF-related APS IDs, wherein, when a value of the ALF availability flag is equal to 1, the header information includes the information related to a number of ALF-related APS IDs, and wherein a value of the information related to a number of ALF-related APS IDs is equal to the number of ALF-related APS IDs. ### Claim 5 (depends on 1) The image decoding method of claim 1, wherein the absolute values of luma filter coefficients for the ALF procedure are within a predetermined range. ### Claim 6 (depends on 1) The image decoding method of claim 1, wherein the performing the ALF procedure comprises: deriving absolute values of chroma filter coefficients for the ALF procedure based on the ALF data; deriving chroma filter coefficients for the ALF procedure based on the absolute values of chroma filter coefficients for the ALF procedure; and generating modified chroma reconstructed samples based on the reconstructed samples and the chroma filter coefficients, wherein the ALF data includes information related to absolute values of chroma filter coefficients for the ALF procedure, and wherein the information related to absolute values of chroma filter coefficients for the ALF procedure is coded based on ue(v). ### Claim 7 (depends on 6) The image decoding method of claim 6, wherein the absolute values of chroma filter coefficients for the ALF procedure are within a predetermined range. ### Claim 8 An image encoding method performed by an encoding apparatus, the method comprising: deriving residual samples for a current block; generating residual information based on the residual samples; generating reconstructed samples based on the residual information; generating ALF data for an adaptive loop filter (ALF) procedure of the reconstructed samples; and encoding image information including the residual information and the ALF data, wherein the ALF data includes information related to absolute values of luma filter coefficients for the ALF procedure, and wherein the information related to absolute values of luma filter coefficients for the ALF procedure is coded based on ue(v). ### Claim 9 (depends on 8) The image encoding method of claim 8, wherein the image information includes parameter sets, wherein at least one of the parameter sets includes an adaptation parameter set (APS), and wherein the ALF data is included in the APS. ### Claim 10 (depends on 8) The image encoding method of claim 8, wherein the image information includes header information and ALF-related adaptation parameter set (APS), wherein the header information includes information related to a number of ALF-related APS IDs, wherein the number of ALF-related APS IDs is derived based on a value of information related to the number of ALF-related APS IDs, and wherein a number of ALF-related APS ID syntax elements equal to the number of ALF-related APS IDs is included in the header information. ### Claim 11 (depends on 8) The image encoding method of claim 8, wherein the image information includes header information and an ALF-related adaptation parameter set (APS), wherein the header information includes an ALF availability flag indicating whether or not the ALF is available for usage within a picture or slice and information related to a number of ALF-related APS IDs, wherein, when a value of the ALF availability flag is equal to 1, the header information includes the information related to a number of ALF-related APS IDs, and wherein a value of the information related to a number of ALF-related APS IDs is equal to the number of ALF-related APS IDs. ### Claim 12 (depends on 8) The image encoding method of claim 8, wherein the absolute values of luma filter coefficients for the ALF procedure are within a predetermined range. ### Claim 13 (depends on 8) The image encoding method of claim 8, wherein the performing the ALF procedure comprises: deriving absolute values of chroma filter coefficients for the ALF procedure based on the ALF data; deriving chroma filter coefficients for the ALF procedure based on the absolute values of chroma filter coefficients for the ALF procedure; and generating modified chroma reconstructed samples based on the reconstructed samples and the chroma filter coefficients, wherein the ALF data includes information related to absolute values of chroma filter coefficients for the ALF procedure, and wherein the information related to absolute values of chroma filter coefficients for the ALF procedure is coded based on ue(v). ### Claim 14 (depends on 13) The image encoding method of claim 13, wherein the absolute values of chroma filter coefficients for the ALF procedure are within a predetermined range. ### Claim 15 A non-transitory computer readable digital storage medium storing a bitstream generated by a image encoding method, the image encoding method comprising: deriving residual samples for a current block; generating residual information based on the residual samples; generating reconstructed samples based on the residual information; generating ALF data for an adaptive loop filter (ALF) procedure of the reconstructed samples; and encoding image information to generate the bitstream, wherein the image information includes the residual information and the ALF data, wherein the ALF data includes information related to absolute values of luma filter coefficients for the ALF procedure, and wherein the information related to absolute values of luma filter coefficients for the ALF procedure is coded based on ue(v).