# US 11,451,792 B2 · Chroma intra prediction method and device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,451,792 B2 - Document ID: US11451792B2 - Status: Granted - Kind: B2 - Application number: 17/361,625 - Filed: 2021-06-29 - Published: 2021-10-21 - Granted: 2022-09-20 - Earliest claimed: 2019-01-02 - Assignees: Guangdong Oppo Mobile Telecommunications Corp., Ltd. - Applicants: Guangdong Oppo Mobile Telecommunications Corp., Ltd. - Inventors: Junyan Huo; Yanzhuo Ma; Shuai Wan; Fuzheng Yang; Xinwei Li - Web page: https://patentgrep.com/patent/US11451792B2 ## 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 19/11: among a plurality of spatial predictive coding modes - 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 19/463: by compressing encoding parameters before transmission - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A chroma intra prediction method and device are provided. The method applied to a decoder includes parsing bitstream data corresponding to a current chroma block, and determining that a prediction mode corresponding to the current chroma block is a direct mode (DM); determining an intra prediction mode of the current chroma block from a set of chroma prediction modes, wherein the set of chroma prediction modes comprises at least one of DM, LM, LM_T or LM_L; and determining a reconstructed value of the current chroma block according to the intra prediction mode. ## Claims ### Claim 1 A chroma intra prediction method, applied to a decoder, the method comprising: parsing bitstream data corresponding to a current chroma block, and determining that a prediction mode corresponding to the current chroma block is a direct mode (DM); before determining a set of chroma prediction modes based on at least one modified candidate mode, acquiring a linear mode corresponding to the current chroma block from the bitstream data; determining an intra prediction mode of the current chroma block from a set of chroma prediction modes, wherein the set of chroma prediction modes comprises at least one of the DM or the linear mode; and determining a reconstructed value of the current chroma block according to the intra prediction mode. ### Claim 2 (depends on 1) The method of claim 1, wherein when a luma prediction mode corresponding to the DM is a direct current (DC) mode or a planar mode, the set of chroma prediction modes comprises a diagonal angular mode with prediction direction index number 66. ### Claim 3 (depends on 1) The method of claim 1, further comprising determining the at least one modified candidate mode, wherein: when a luma prediction mode corresponding to the DM is a direct current (DC) mode or a planar mode, the set of chroma prediction modes is determined based on the at least one modified candidate mode; and determining the at least one modified candidate mode comprises adjusting a mode with a prediction direction index number 66 by a first angle in a first angular direction and adjusting a mode with a prediction direction index number 2 by the first angle in a direction opposite to the first angular direction to obtain derived angles of the at least one modified candidate mode; the prediction direction index number 66 points in a top-right direction; and the prediction direction index number 2 points in a bottom-left direction. ### Claim 4 (depends on 2) The method of claim 2, wherein when a luma prediction mode corresponding to the DM is the DC mode, the set of chroma prediction modes is determined at least according to the Planar mode and the at least one modified candidate mode, and when a luma prediction mode corresponding to the DM is the Planar mode, the set of chroma prediction modes is determined at least according to the DC mode and the at least one modified candidate mode. ### Claim 5 (depends on 1) The method of claim 1, wherein when a luma prediction mode corresponding to the DM is one of a DC mode, Planar mode, VER mode or HOR mode, the set of chroma prediction modes comprises an angular mode with an index number 66. ### Claim 6 A chroma intra prediction method, applied to an encoder, the method comprising: determining that a prediction mode corresponding to a current chroma block is a direct mode (DM); before determining a set of chroma prediction modes based on at least one modified candidate mode, acquiring a linear mode corresponding to the current chroma block from bitstream data; determining an intra prediction mode of the current chroma block from a set of chroma prediction modes, wherein the set of chroma prediction modes comprises at least one of the DM or the linear mode; and determining a reconstructed value of the current chroma block according to the intra prediction mode. ### Claim 7 (depends on 6) The method of claim 6, wherein when a luma prediction mode corresponding to the DM is a direct current (DC) mode or a planar mode, the set of chroma prediction modes comprises a diagonal angular mode with prediction direction index number 66 pointing towards the top-right direction. ### Claim 8 (depends on 6) The method of claim 6, further comprising determining the at least one modified candidate mode wherein: when a luma prediction mode corresponding to the DM is a direct current (DC) mode or a planar mode, the set of chroma prediction modes is determined based on the at least one modified candidate mode; and determining the at least one modified candidate mode comprises adjusting a mode with a prediction direction index number 66 by a first angle in a first angular direction and adjusting a mode with a prediction direction index number 2 by the first angle in a direction opposite to the first angular direction to obtain derived angles of the at least one modified candidate mode; the prediction direction index number 66 points in a top-right direction; and the prediction direction index number 2 points in a bottom-left direction. ### Claim 9 (depends on 7) The method of claim 7, wherein when a luma prediction mode corresponding to the DM is the DC mode, the set of chroma prediction modes is determined at least according to the Planar mode and the at least one modified candidate mode, when a luma prediction mode corresponding to the DM is the Planar mode, the set of chroma prediction modes is determined at least according to the DC mode and the at least one modified candidate mode. ### Claim 10 (depends on 6) The method of claim 6, wherein when a luma prediction mode corresponding to the DM is one of a DC mode, Planar mode, VER mode or HOR mode, the set of chroma prediction modes comprises an angular mode with an index number 66. ### Claim 11 A chroma intra prediction device, applied to a decoder, the device comprising: a processor, a memory storing instructions executable by the processor, a communication interface, and a bus for connecting the processor, the memory and the communication interface, wherein the processor is configured to execute the instructions to perform operations of: parsing bitstream data corresponding to a current chroma block, and determining that a prediction mode corresponding to the current chroma block is a direct mode (DM); before determining a set of chroma prediction modes based on at least one modified candidate mode, acquiring a linear mode corresponding to the current chroma block from the bitstream data; determining an intra prediction mode of the current chroma block from a set of chroma prediction modes, wherein the set of chroma prediction modes comprises at least one of the DM or the linear mode; and determining a reconstructed value of the current chroma block according to the intra prediction mode. ### Claim 12 (depends on 11) The device of claim 11, wherein when a luma prediction mode corresponding to the DM is a direct current (DC) mode or a planar mode, the set of chroma prediction modes comprises a diagonal angular mode with prediction direction index number 66. ### Claim 13 (depends on 11) The device of claim 11, further comprising determining the at least one modified candidate mode, wherein: when a luma prediction mode corresponding to the DM is a direct current (DC) mode or a planar mode, the set of chroma prediction modes is determined based on the at least one modified candidate mode; and determining the at least one modified candidate mode comprises adjusting a mode with a prediction direction index number 66 by a first angle in a first angular direction and adjusting a mode with a prediction direction index number 2 by the first angle in a direction opposite to the first angular direction to obtain derived angles of the at least one modified candidate mode; the prediction direction index number 66 points in a top-right direction; and the prediction direction index number 2 points in a bottom-left direction. ### Claim 14 (depends on 12) The device of claim 12, wherein: when a luma prediction mode corresponding to the DM is the DC mode, the set of chroma prediction modes is determined at least according to the Planar mode and the at least one modified candidate mode; and when a luma prediction mode corresponding to the DM is the Planar mode, the set of chroma prediction modes is determined at least according to the DC mode and the at least one modified candidate mode. ### Claim 15 (depends on 11) The device of claim 11, when a luma prediction mode corresponding to the DM is one of a DC mode, Planar mode, VER mode or HOR mode, the set of chroma prediction modes comprises an angular mode with an index number 66. ### Claim 16 A chroma intra prediction device, applied to an encoder, the device comprising: a processor, a memory storing instructions executable by the processor, a communication interface, and a bus for connecting the processor, the memory and the communication interface, wherein the processor is configured to execute the instructions to perform operations of: determining that a prediction mode corresponding to a current chroma block is a direct mode (DM); before determining a set of chroma prediction modes based on at least one modified candidate mode, acquiring a linear mode corresponding to the current chroma block from bitstream data; determining an intra prediction mode of the current chroma block from a set of chroma prediction modes, wherein the set of chroma prediction modes comprises at least one of the DM or the linear mode; and determining a reconstructed value of the current chroma block according to the intra prediction mode. ### Claim 17 (depends on 16) The device of claim 16, wherein when a luma prediction mode corresponding to the DM is a direct current (DC) mode or a planar mode, the set of chroma prediction modes comprises a diagonal angular mode with prediction direction index number 66. ### Claim 18 (depends on 16) The device of claim 16, further comprising determining the at least one modified candidate mode, wherein: when a luma prediction mode corresponding to the DM is a direct current (DC) mode or a planar mode, the set of chroma prediction modes is determined based on the at least one modified candidate mode; and determining the modified candidate modes comprises adjusting a mode with a prediction direction index number 66 by a first angle in a first angular direction and adjusting a mode with a prediction direction index number 2 by the first angle in a direction opposite to the first angular direction to obtain derived angles of the modified candidate modes; the prediction direction index number 66 points in a top-right direction; and the prediction direction index number 2 points in a bottom-left direction. ### Claim 19 (depends on 17) The device of claim 17, wherein when a luma prediction mode corresponding to the DM is the DC mode, the set of chroma prediction modes is determined at least according to the Planar mode and the at least one modified candidate mode, when a luma prediction mode corresponding to the DM is the Planar mode, the set of chroma prediction modes is determined at least according to the DC mode and the at least one modified candidate mode. ### Claim 20 (depends on 16) The device of claim 16, wherein when a luma prediction mode corresponding to the DM is one of a DC mode, Planar mode, VER mode or HOR mode, the set of chroma prediction modes comprises an angular mode with an index number 66. ### Claim 21 (depends on 1) The method of claim 1, wherein when a luma prediction mode corresponding to the DM is a direct current (DC) mode or a planar mode, the intra prediction mode comprises at least one of a diagonal angular mode with prediction direction index number 34 pointing in the top-left direction or a diagonal angular mode with prediction direction index number 2 pointing in the bottom-left direction. ### Claim 22 (depends on 1) The method of claim 1, wherein the linear mode is LM, LM_T or LM_L.