# US 2021/0344933 A1 · Intra prediction method and encoding apparatus and decoding apparatus using same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0344933 A1 - Document ID: US20210344933A1 - Status: Published application - Kind: A1 - Application number: 17/377,005 - Filed: 2021-07-15 - Published: 2021-11-04 - Earliest claimed: 2010-12-08 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Yong Joon JEON; Seung Wook Park; Jung Sun Kim; Joon Young Park; Byeong Moon Jeon; Jee Hyun Lim - Web page: https://patentgrep.com/patent/US20210344933A1 ## CPC - H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction - H04N 19/00: Methods or arrangements for coding, decoding, compressing or decompressing digital video signals - 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 19/593: involving spatial prediction techniques - H04N 19/86: involving reduction of coding artifacts, e.g. of blockiness - 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 19/82: involving filtering within a prediction loop - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An intra prediction method and a device using the intra prediction method are provided. The intra prediction method includes the steps of: deriving a current prediction mode as a prediction anode of a current block; constructing neighboring samples of the current block with available reference samples; filtering the available reference samples; and generating predicted samples of the current block on the basis of the filtered available reference samples,. The filtering step includes performing the filtering using the available reference sample located in the prediction direction of the current prediction mode and a predetermined number of available reference samples neighboring to the prediction direction of the current prediction mode. ## Claims ### Claim at position 1 1-16. (canceled) ### Claim 17 An image decoding method using intra prediction, by a decoding apparatus, the method comprising: obtaining residual information for a current block and prediction information including prediction mode information representing an intra prediction mode for the current block; deriving the intra prediction mode for the current block based on the prediction mode information, wherein the intra prediction mode is determined as a directional prediction mode from intra prediction modes including 33 directional prediction modes and at least one non-directional prediction mode; deriving neighboring reference samples of the current block; performing filtering on at least one of the reference samples; generating a prediction sample of the current block based on a filtered reference sample; generating a residual sample of the current block based on the residual information; and generating a reconstructed picture based on the prediction sample and the residual sample, wherein the filtered reference sample is filtered by using a first reference sample located in a prediction direction of the intra prediction mode with regard to a location of the prediction sample and reference samples adjacent to the first reference sample, wherein, based on the intra prediction mode for the current block being derived as a vertical intra prediction mode and the first neighboring reference sample being located on a top side of the current block, a filtered sample value for the first neighboring reference sample is derived based on following equation by using the first neighboring reference sample, a second neighboring reference sample located on a left side of the first neighboring reference sample and a third neighboring reference sample located on a right side of the first neighboring reference sample, r(x−1)+2*r(x)+r(x+1)+2)>>2 wherein, the r(x) represents a sample value of the first neighboring reference sample, the r(x−1) represents a value of the second neighboring reference sample and the r(x+1) represents a sample value of the third neighboring reference sample, wherein, based on the intra prediction mode for the current block being derived as a horizontal intra prediction mode and the first neighboring reference sample being located on a left side of the current block, a filtered sample value for the first neighboring reference sample is derived based on following equation by using the first neighboring reference sample, a fourth neighboring reference sample located on an upper side of the first neighboring reference sample and a fifth neighboring reference sample located on a lower side of the first neighboring reference sample, (r(y−1)+2*r(y)+r(y+1)+2)>>2 wherein, the r(y) represents a sample value of the first neighboring reference sample, the r(y−1) represents a value of the fourth neighboring reference sample and the r(y+1) represents a sample value of the fifth neighboring reference sample. ### Claim 18 (depends on 17) The method of claim 17, wherein a filtering coefficient for the first reference sample is greater than filtering coefficients for the reference samples adjacent to the first reference sample. ### Claim 19 (depends on 17) The method of claim 17, wherein the filtered reference sample is filtered by applying a 3-tap filter with a filtering coefficient of [1 2 1] to the first reference sample. ### Claim 20 (depends on 17) The method of claim 17, wherein it is determined whether the filtering is performed depending on a size and the intra prediction mode of the current block. ### Claim 21 (depends on 20) The method of claim 20, wherein when it is determined that the filtering is not performed, the prediction sample is generated based on the first reference sample, and wherein a smoothing process using 2-tap coefficients is performed on the first reference sample. ### Claim 22 An image encoding method using intra prediction, by an encoding apparatus, the method comprising: determining an intra prediction mode for a current block, wherein the intra prediction mode is determined as a directional prediction mode from intra prediction modes including 33 directional prediction modes and at least one non-directional prediction mode; deriving neighboring reference samples of the current block; performing filtering on at least one of the reference samples; generating a prediction sample of the current block based on a filtered reference sample; generating a residual sample of the current block based on the prediction sample; and encoding a bitstream including residual information for the current block and prediction information including prediction mode information representing the intra prediction mode for the current block, wherein the filtered reference sample is filtered by using a first reference sample located in a prediction direction of the intra prediction mode with regard to a location of the prediction sample and reference samples adjacent to the first reference sample, wherein, based on the intra prediction mode for the current block being derived as a vertical intra prediction mode and the first neighboring reference sample being located on a top side of the current block, a filtered sample value for the first neighboring reference sample is derived based on following equation by using the first neighboring reference sample, a second neighboring reference sample located on a left side of the first neighboring reference sample and a third neighboring reference sample located on a right side of the first neighboring reference sample, (r(x−1)+2*r(x)+r(x+1)+2)>>2 wherein, the r(x) represents a sample value of the first neighboring reference sample, the r(x−1) represents a value of the second neighboring reference sample and the r(x+1) represents a sample value of the third neighboring reference sample, wherein, based on the intra prediction mode for the current block being derived as a horizontal intra prediction mode and the first neighboring reference sample being located on a left side of the current block, a filtered sample value for the first neighboring reference sample is derived based on following equation by using the first neighboring reference sample, a fourth neighboring reference sample located on an upper side of the first neighboring reference sample and a fifth neighboring reference sample located on a lower side of the first neighboring reference sample, (r(y−1)+2*r(y)+r(y+1)+2)>>2 wherein, the r(y) represents a sample value of the first neighboring reference sample, the r(y−1) represents a value of the fourth neighboring reference sample and the r(y+1) represents a sample value of the fifth neighboring reference sample. ### Claim 23 (depends on 22) The method of claim 22, wherein a filtering coefficient for the first reference sample is greater than filtering coefficients for the reference samples adjacent to the first reference sample. ### Claim 24 (depends on 22) The method of claim 22, wherein the filtered reference sample is filtered by applying a 3-tap filter with a filtering coefficient of [1 2 1] to the first reference sample. ### Claim 25 (depends on 22) The method of claim 22, wherein it is determined whether the filtering is performed depending on a size and the intra prediction mode of the current block. ### Claim 26 (depends on 25) The method of claim 25, wherein when it is determined that the filtering is not performed, the prediction sample is generated based on the first reference sample, and wherein a smoothing process using 2-tap coefficients is performed on the first reference sample. ### Claim 27 A non-transitory computer-readable storage medium storing a bitstream encoded by a method, the method comprising: determining an intra prediction mode for a current block, wherein the intra prediction mode is determined as a directional prediction mode from intra prediction modes including 33 directional prediction modes and at least one non-directional prediction mode; deriving neighboring reference samples of the current block; performing filtering on at least one of the reference samples; generating a prediction sample of the current block based on a filtered reference sample; generating a residual sample of the current block based on the prediction sample; and encoding the bitstream including residual information for the current block and prediction information including prediction mode information representing the intra prediction mode for the current block, wherein the filtered reference sample is filtered by using a first reference sample located in a prediction direction of the intra prediction mode with regard to a location of the prediction sample and reference samples adjacent to the first reference sample, wherein, based on the intra prediction mode for the current block being derived as a vertical intra prediction mode and the first neighboring reference sample being located on a top side of the current block, a filtered sample value for the first neighboring reference sample is derived based on following equation by using the first neighboring reference sample, a second neighboring reference sample located on a left side of the first neighboring reference sample and a third neighboring reference sample located on a right side of the first neighboring reference sample, (r(x−1)+2*r(x)+r(x+1)+2)>>2 wherein, the r(x) represents a sample value of the first neighboring reference sample, the r(x−1) represents a value of the second neighboring reference sample and the r(x+1) represents a sample value of the third neighboring reference sample, wherein, based on the intra prediction mode for the current block being derived as a horizontal intra prediction mode and the first neighboring reference sample being located on a left side of the current block, a filtered sample value for the first neighboring reference sample is derived based on following equation by using the first neighboring reference sample, a fourth neighboring reference sample located on an upper side of the first neighboring reference sample and a fifth neighboring reference sample located on a lower side of the first neighboring reference sample, (r(y−1)+2*r(y)+r(y+1)+2)>>2 wherein, the r(y) represents a sample value of the first neighboring reference sample, the r(y−1) represents a value of the fourth neighboring reference sample and the r(y+1) represents a sample value of the fifth neighboring reference sample.