# US 11,445,183 B2 · Chroma intra mode derivation in screen content coding > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,445,183 B2 - Document ID: US11445183B2 - Status: Granted - Kind: B2 - Application number: 17/528,288 - Filed: 2021-11-17 - Published: 2022-03-10 - Granted: 2022-09-13 - Earliest claimed: 2019-06-28 - Assignees: Bytedance Inc. - Applicants: Bytedance Inc. - Inventors: Weijia Zhu; Li Zhang; Jizheng Xu - Web page: https://patentgrep.com/patent/US11445183B2 ## CPC - 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 19/132: Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking - H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction - 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 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A method of video processing is described. The method includes deriving, for a current video block of a video that is a chroma block and coded in a chroma DM mode, an intra prediction mode for the current video block according to a rule related to a coding mode of the current video block; and performing a conversion between the current video block and a coded presentation of the video, wherein the rule specifies to derive the intra prediction mode based on an intra prediction direction of a corresponding luma block used to derive the chroma DM mode and coded using a block differential pulse code modulation representation of a quantized residual block corresponding to the current video block. ## Claims ### Claim 1 A method of processing video data, comprising: deriving, for a conversion between a current chroma block of a video and a bitstream of the video, a chroma prediction mode for the current chroma block based on a luma coding information of a first luma block corresponding to the current chroma block; and performing the conversion based on the derived chroma prediction mode, wherein in response to the first luma block being coded with a differential coding mode in which differences between quantized residuals derived with a luma prediction mode and predictions of the quantized residuals are included in the bitstream, the chroma prediction mode is identical to the luma prediction mode, wherein the chroma prediction mode being identical to the luma prediction mode is further based on a value of a syntax element intra_chroma_pred_mode, and wherein the syntax element intra_chroma_pred_mode is used to specify a mapping relation between a chroma component intra mode and a luma component intra mode, wherein in response to the first luma block being coded with a first prediction mode and/or a variance of the first prediction mode, the chroma prediction mode is derived as a DC mode, and wherein in the first prediction mode, reconstructed samples are represented by a set of representative color values, and the set of representative color values comprises at least one of 1) palette predictors, 2) escape samples, or 3) palette information included in the bitstream. ### Claim 2 (depends on 1) The method of claim 1, wherein the first luma block covers a corresponding center position of the current chroma block. ### Claim 3 (depends on 1) The method of claim 1, wherein the syntax element intra_chroma_pred_mode specifies that a DM mode is applied on the chroma block, and wherein in the DM mode, the chroma component intra mode is identical to the luma component intra mode. ### Claim 4 (depends on 1) The method of claim 1, wherein the chroma prediction mode is a vertical prediction mode in a case where the luma prediction mode is a vertical prediction mode. ### Claim 5 (depends on 1) The method of claim 1, wherein the chroma prediction mode is a horizontal prediction mode in a case where the luma prediction direction is a horizontal prediction mode. ### Claim 6 (depends on 1) The method of claim 1, wherein in response to the first luma block is coded with a second prediction mode and/or a variance of the second prediction mode, the chroma prediction mode is derived as a DC mode, wherein in the second prediction mode, prediction samples are derived from blocks of sample values of a same decoded picture as determined by block vectors. ### Claim 7 (depends on 1) The method of claim 1, wherein in a case where the first luma block is a neighboring block of a second luma block, a default mode is assigned to the first luma block for constructing the intra mode candidate list of the second block in response to the second luma block and the first luma block being in a different slice or tile. ### Claim 8 (depends on 7) The method of claim 7, wherein in a case where the first luma block is the neighboring block of the second luma block, the default mode is assigned to the first luma block for constructing the intra mode candidate list of the second block in response to the first luma block being coded with a first prediction mode or a second prediction mode, wherein in the first prediction mode, reconstructed samples are represented by a set of representative color values, and the set of representative color values comprises at least one of 1) palette predictors, 2) escape samples, or 3) palette information included in the bitstream, and wherein in the second prediction mode, prediction samples are derived from blocks of sample values of a same decoded picture as determined by block vectors. ### Claim 9 (depends on 8) The method of claim 8, wherein the default mode is a planar mode. ### Claim 10 (depends on 1) The method of claim 1, wherein the conversion comprises encoding the current chroma block into the bitstream. ### Claim 11 (depends on 1) The method of claim 1, wherein the conversion comprises decoding the current chroma block from the bitstream. ### Claim 12 An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to: derive, for a conversion between a current chroma block of a video and a bitstream of the video, a chroma prediction mode for the current chroma block based on a luma coding information of a first luma block corresponding to the current chroma block; and perform the conversion based on the derived chroma prediction mode, wherein in response to the first luma block being coded with a differential coding mode in which differences between quantized residuals derived with a luma prediction mode and predictions of the quantized residuals are included in the bitstream, the chroma prediction mode is identical to the luma prediction mode, wherein the chroma prediction mode being identical to the luma prediction mode is further based on a value of a syntax element intra_chroma_pred_mode, and wherein the syntax element intra_chroma_pred_mode is used to specify a mapping relation between a chroma component intra mode and a luma component intra mode, wherein in response to the first luma block being coded with a first prediction mode and/or a variance of the first prediction mode, the chroma prediction mode is derived as a DC mode, and wherein in the first prediction mode, reconstructed samples are represented by a set of representative color values, and the set of representative color values comprises at least one of 1) palette predictors, 2) escape samples, or 3) palette information included in the bitstream. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein the first luma block covers a corresponding center position of the current chroma block. ### Claim 14 (depends on 12) The apparatus of claim 12, wherein the syntax element intra_chroma_pred_mode specifies that a DM mode is applied on the chroma block, and wherein in the DM mode, the chroma component intra mode is identical to the luma component intra mode. ### Claim 15 (depends on 12) The apparatus of claim 12, wherein the chroma prediction mode is a vertical prediction mode in a case where the luma prediction mode is a vertical prediction mode; or the chroma prediction mode is a horizontal prediction mode in a case where the luma prediction direction is a horizontal prediction mode. ### Claim 16 (depends on 12) The apparatus of claim 12, wherein in response to the first luma block is coded with a second prediction mode and/or a variance of the second prediction mode, the chroma prediction mode is derived as a DC mode, wherein in the second prediction mode, prediction samples are derived from blocks of sample values of a same decoded picture as determined by block vectors. ### Claim 17 (depends on 12) The apparatus of claim 12, wherein in a case where the first luma block is a neighboring block of a second luma block, a default mode is assigned to the first luma block for constructing the intra mode candidate list of the second block in response to the second luma block and the first luma block being in a different slice or tile. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein in a case where the first luma block is the neighboring block of the second luma block, the default mode is assigned to the first luma block for constructing the intra mode candidate list of the second block in response to the first luma block being coded with a first prediction mode or a second prediction mode, wherein in the first prediction mode, reconstructed samples are represented by a set of representative color values, and the set of representative color values comprises at least one of 1) palette predictors, 2) escape samples, or 3) palette information included in the bitstream, and wherein in the second prediction mode, prediction samples are derived from blocks of sample values of a same decoded picture as determined by block vectors. ### Claim 19 A non-transitory computer-readable storage medium storing instructions that cause a processor to: derive, for a conversion between a current chroma block of a video and a bitstream of the video, a chroma prediction mode for the current chroma block based on a luma coding information of a first luma block corresponding to the current chroma block; and perform the conversion based on the derived chroma prediction mode, wherein in response to the first luma block being coded with a differential coding mode in which differences between quantized residuals derived with a luma prediction mode and predictions of the quantized residuals are included in the bitstream, the chroma prediction mode is identical to the luma prediction mode, wherein the chroma prediction mode being identical to the luma prediction mode is further based on a value of a syntax element intra_chroma_pred_mode, and wherein the syntax element intra_chroma_pred_mode is used to specify a mapping relation between a chroma component intra mode and a luma component intra mode, wherein in response to the first luma block being coded with a first prediction mode and/or a variance of the first prediction mode, the chroma prediction mode is derived as a DC mode, and wherein in the first prediction mode, reconstructed samples are represented by a set of representative color values, and the set of representative color values comprises at least one of 1) palette predictors, 2) escape samples, or 3) palette information included in the bitstream. ### Claim 20 A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: deriving, for a current chroma block of a video, the chroma prediction mode for the current chroma block based on a luma coding information of a first luma block corresponding to the current chroma block; and generating the bitstream based on the derived chroma prediction mode, wherein in response to the first luma block being coded with a differential coding mode in which differences between quantized residuals derived with a luma prediction mode and predictions of the quantized residuals are included in the bitstream, the chroma prediction mode is identical to the luma prediction mode, wherein the chroma prediction mode being identical to the luma prediction mode is further based on a value of a syntax element intra_chroma_pred_mode, and wherein the syntax element intra_chroma_pred_mode is used to specify a mapping relation between a chroma component intra mode and a luma component intra mode, wherein in response to the first luma block being coded with a first prediction mode and/or a variance of the first prediction mode, the chroma prediction mode is derived as a DC mode, and wherein in the first prediction mode, reconstructed samples are represented by a set of representative color values, and the set of representative color values comprises at least one of 1) palette predictors, 2) escape samples, or 3) palette information included in the bitstream.