# US 2020/0288135 A1 · New sample sets and new down-sampling schemes for linear component sample prediction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0288135 A1 - Document ID: US20200288135A1 - Status: Published application - Kind: A1 - Application number: 16/645,432 - Filed: 2018-09-28 - Published: 2020-09-10 - Earliest claimed: 2017-10-09 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Guillaume LAROCHE; Christophe GISQUET; Patrice ONNO; Jonathan TAQUET - Web page: https://patentgrep.com/patent/US20200288135A1 ## CPC - 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 19/593: involving spatial prediction techniques - 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 19/11: among a plurality of spatial predictive coding modes - H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) - H04N 19/147: according to rate distortion criteria (rate-distortion as a criterion for motion estimation H04N19/567) - H04N 19/157: Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter - H04N 19/167: Position within a video image, e.g. region of interest [ROI] - 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 19/59: involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution - H04N 19/82: involving filtering within a prediction loop - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract The disclosure regards cross-component prediction and methods for obtaining a chroma sample from an associated luma sample using a linear model with parameters. The parameters are derived from luma and chroma samples neighbouring the luma and chroma blocks considered. The luma samples are down-sampled to match chroma resolution. A competition between several luma down-sampling schemes is proposed wherein two 1-tap filters are competing. This reduces computational complexity at the encoder. Also a competition between several sample sets defining the neighbouring luma and chroma samples used for parameter derivation is conducted, wherein a competing sample set is an irregular sample set. The irregular sample set preferably comprises only samples from second lines next to respective first lines of outer neighbouring samples parallel and immediately adjacent to respectively the left boundary and the top boundary of the current block. This improves chroma prediction and thus coding efficiency. ## Claims ### Claim at position 1 1-7. (canceled) ### Claim 8 A method of obtaining a first-colour-component sample for a current first-colour-component block of a multi-colour-component frame from an associated reconstructed second-colour-component sample of a current second-colour-component block in the same frame using a linear model with one or more parameters, the two blocks having the same size, the method comprising: deriving the one or more parameters of the linear model based on a neighbouring first-colour-component sample set comprising first-colour-component samples neighbouring the current first-colour-component block and a neighbouring second-colour-component sample set comprising reconstructed second-colour-component samples neighbouring the current second-colour-component block, and obtaining the first-colour-component sample using the linear model with the one or more parameters derived and the associated reconstructed second-colour-component sample in the current second-colour-component block, wherein deriving the one or more parameters includes obtaining one from a plurality of reference sample sets to define the neighbouring first-colour-component and second-colour-component sample sets for the parameter derivation, the plurality of reference sample sets including one or more irregular sample sets, wherein an irregular sample set is built from two lines of outer neighbouring samples parallel and adjacent to the top boundary of the current block and the two lines of outer neighbouring samples parallel and adjacent to the left boundary of the current block, and for at least one position along the top or left boundary of the current block, only one sample is selected from the sample of the first line adjacent to the boundary and the sample of the next and second line, and at least one sample of the next and second line along the same boundary is selected. ### Claim 9 (depends on 8) The method of claim 8, wherein at least one sample in the first line is not selected to build one or more of the irregular sample sets. ### Claim 10 (depends on 8) The method of claim 8, wherein, for each of the top and left boundaries, the two lines are immediately adjacent to the boundary considered. ### Claim 11 (depends on 10) The method of claim 10, wherein the one or more irregular sample sets includes at least one non-adjacent sample set comprising, along the same top or left boundary, samples from the next and second line only. ### Claim 12 A method of obtaining a first-colour-component sample for a current first-colour-component block of a multi-colour-component frame from an associated reconstructed second-colour-component sample of a current second-colour-component block in the same frame using a linear model with one or more parameters, the two blocks having the same size, the method comprising: deriving the one or more parameters of the linear model based on a neighbouring sample set comprising first-colour-component or second-colour-component samples neighbouring respectively the current first-colour-component or second-colour-component block and obtaining the first-colour-component sample using the linear model with the one or more parameters derived and the associated reconstructed second-colour-component sample, wherein deriving the one or more parameters includes obtaining one from a plurality of reference sample sets, including one or more irregular sample sets, to define the neighbouring first-colour-component or second-colour-component sample set for the parameter derivation, at least one irregular sample set comprising only samples from second lines next to respective first lines of outer neighbouring samples parallel and immediately adjacent to respectively the left boundary and the top boundary of the current block. ### Claim 13 (depends on 12) The method of claim 12, wherein the one or more irregular sample sets includes at least one shifted sample set comprising, for the same position along the top or left boundary, at most one from the sample of the first line and the sample of the next and second line. ### Claim 14 (depends on 13) The method of claim 13, wherein the shifted sample set comprises exactly one sample from the sample of the first line and the sample of the next and second line, for each position along the top or left boundary. ### Claim 15 (depends on 12) The method of claim 12, wherein the one or more irregular sample sets includes at least one L-shaped sample set comprising, along the same top or left boundary, the samples of the first and second lines for a first position along the boundary and only one sample from the sample of the first line and the sample of the next and second line for a second and different position along the boundary. ### Claim 16 (depends on 12) The method of claim 12, wherein the one or more irregular sample sets includes at least one square sample set comprising the samples of the first and second lines for each position of a continuous subpart of positions along the top or left boundary and comprising, for the remaining subpart or subparts of positions, no sample from the first and second lines. ### Claim 17 (depends on 12) The method of claim 12, wherein one or more of the irregular sample sets comprises the four samples forming a square continuing, at the top left corner of the current block, the two lines adjacent to the top and left boundaries. ### Claim 18 (depends on 12) The method of claim 12, wherein one or more of the irregular sample sets comprise a different number of samples from the first line and of samples from the next and second line. ### Claim 19 (depends on 12) The method of claim 12, wherein the samples selected along the top boundary for one or more irregular sample sets form a top sample shape that is identical to or mirrored from a left sample shape forming the samples selected along the left boundary. ### Claim 20 (depends on 12) The method of claim 12, wherein one or more of the irregular sample sets are built by selecting some samples from the two lines based on the samples values. ### Claim 21 A method of obtaining a chroma sample for a current chroma block from an associated reconstructed luma sample of a current luma block in the same frame using a linear model with one or more parameters, the method comprising: deriving the one or more parameters of the linear model based on a neighbouring chroma sample set comprising chroma samples neighbouring the current chroma block and a neighbouring luma sample set, the neighbouring luma sample set comprises reconstructed luma samples neighbouring the current luma block that are down-sampled to match chroma resolution, obtaining the chroma sample using the linear model with the one or more parameters derived and the associated reconstructed luma samples in the current luma block made of reconstructed luma samples down-sampled to match chroma resolution, obtaining one reference LM mode from a plurality of reference LM modes, each of which being made of one down-sampling scheme and one sample set, to down-sample, using the thus-obtained down-sampling scheme, the reconstructed luma samples to match chroma resolution for the parameter derivation and for the chroma intra predictor generation and to define, using the thus-obtained sample set, the neighbouring luma and chroma sample sets for the parameter derivation, wherein at least one reference LM mode includes an irregular sample set built from two lines of outer neighbouring samples parallel and adjacent to the top boundary of the current block and the two lines of outer neighbouring samples parallel and adjacent to the left boundary of the current block, and for at least one position along the top or left boundary of the current block, only one sample is selected from the sample of the first line adjacent to the boundary and the sample of the next and second line, and at least one sample of the next and second line along the same boundary is selected. ### Claim 22 (depends on 21) The method of claim 21, wherein at least one reference LM mode includes a down-sampling scheme that selects, as down-sampled reconstructed luma sample at a down-sampling position, one reconstructed luma sample in the vicinity of the down-sampling position. ### Claim 23 (depends on 22) The method of claim 22, wherein four of the reference LM modes include four respective down-sampling schemes that select, respectively, top, top right, bottom and bottom right samples of six reconstructed luma samples surrounding the down-sampling position. ### Claim 24 (depends on 21) The method of claim 21, wherein, for each of the top and left boundaries, the two lines are immediately adjacent to the boundary considered. ### Claim 25 (depends on 24) The method of claim 24, wherein the irregular sample set comprises, along the same top or left boundary, samples from the next and second line only. ### Claim 26 (depends on 21) The method of claim 21, further comprising including in a bitstream encoding the current chroma block or retrieving from such bitstream, a single flag identifying the obtained reference LM mode. ### Claim 27 (canceled) ### Claim 28 A device for obtaining a first-colour-component sample for a current first-colour-component block of a multi-colour-component frame from an associated reconstructed second-colour-component sample of a current second-colour-component block in the same frame using a linear model with one or more parameters, the two blocks having the same size, the device comprising at least one microprocessor configured for carrying out the steps of: deriving the one or more parameters of the linear model based on a neighbouring first-colour-component sample set comprising first-colour-component samples neighbouring the current first-colour-component block and a neighbouring second-colour-component sample set comprising reconstructed second-colour-component samples neighbouring the current second-colour-component block, and obtaining the first-colour-component sample using the linear model with the one or more parameters derived and the associated reconstructed second-colour-component sample in the current second-colour-component block, wherein deriving the one or more parameters includes obtaining one from a plurality of reference sample sets to define the neighbouring first-colour-component and second-colour-component sample sets for the parameter derivation, the plurality of reference sample sets including one or more irregular sample sets, wherein an irregular sample set is built from two lines of outer neighbouring samples parallel and adjacent to the top boundary of the current block and the two lines of outer neighbouring samples parallel and adjacent to the left boundary of the current block, and for at least one position along the top or left boundary of the current block, only one sample is selected from the sample of the first line adjacent to the boundary and the sample of the next and second line, and at least one sample of the next and second line along the same boundary is selected. ### Claim 29 A device for obtaining a first-colour-component sample for a current first-colour-component block of a multi-colour-component frame from an associated reconstructed second-colour-component sample of a current second-colour-component block in the same frame using a linear model with one or more parameters, the two blocks having the same size, the device comprising at least one microprocessor configured for carrying out the steps of: deriving the one or more parameters of the linear model based on a neighbouring sample set comprising first-colour-component or second-colour-component samples neighbouring respectively the current first-colour-component or second-colour-component block and obtaining the first-colour-component sample using the linear model with the one or more parameters derived and the associated reconstructed second-colour-component sample, wherein deriving the one or more parameters includes obtaining one from a plurality of reference sample sets, including one or more irregular sample sets, to define the neighbouring first-colour-component or second-colour-component sample set for the parameter derivation, at least one irregular sample set comprising only samples from second lines next to respective first lines of outer neighbouring samples parallel and immediately adjacent to respectively the left boundary and the top boundary of the current block. ### Claim 30 A device for obtaining a chroma sample for a current chroma block from an associated reconstructed luma sample of a current luma block in the same frame using a linear model with one or more parameters, the device comprising at least one microprocessor configured for carrying out the steps of: deriving the one or more parameters of the linear model based on a neighbouring chroma sample set comprising chroma samples neighbouring the current chroma block and a neighbouring luma sample set, the neighbouring luma sample set comprises reconstructed luma samples neighbouring the current luma block that are down-sampled to match chroma resolution, obtaining the chroma sample using the linear model with the one or more parameters derived and the associated reconstructed luma samples in the current luma block made of reconstructed luma samples down-sampled to match chroma resolution, obtaining one reference LM mode from a plurality of reference LM modes, each of which being made of one down-sampling scheme and one sample set, to down-sample, using the thus-obtained down-sampling scheme, the reconstructed luma samples to match chroma resolution for the parameter derivation and for the chroma intra predictor generation and to define, using the thus-obtained sample set, the neighbouring luma and chroma sample sets for the parameter derivation wherein at least one reference LM mode includes an irregular sample set built from two lines of outer neighbouring samples parallel and adjacent to the top boundary of the current block and the two lines of outer neighbouring samples parallel and adjacent to the left boundary of the current block, and for at least one position along the top or left boundary of the current block, only one sample is selected from the sample of the first line adjacent to the boundary and the sample of the next and second line, and at least one sample of the next and second line along the same boundary is selected. ### Claim 31 (depends on 8) A non-transitory computer-readable medium storing a program which, when executed by a microprocessor or computer system in a device, causes the device to perform a method according to claim 8.