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US 2025/0220192 A1Published application
In-loop filtering-based image coding apparatus and method
AssigneeLG Electronics Inc.
InventorsJunghak NAM, Jangwon CHOI
Life of this patent
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Abstract
According to an embodiment of the present document, a method for increasing the accuracy of in-loop filtering is proposed. In an example, the filtering accuracy of chroma blocks can be improved on the basis of luma blocks by performing a cross component adaptive loop filtering process.
Claims3
An apparatus for decoding image information, the apparatus comprising:
- a memory;
- and
- at least one processor connected to the memory, the at least one processor configured to:
- obtain the image information including prediction related information and residual information through a bitstream,
- generate prediction samples based on the prediction related information,
- derive quantized transform coefficients based on the residual information,
- derive transform coefficients based on a dequantization process for the quantized transform coefficients,
- derive residual samples based on an inverse transform process for the transform coefficients,
- generate reconstructed samples based on the prediction samples and the residual samples, wherein the reconstructed samples include reconstructed luma samples and reconstructed chroma samples,
- derive ALF filter coefficients for an adaptive loop filtering (ALF) process of the reconstructed chroma samples,
- generate filtered reconstructed chroma samples based on the reconstructed chroma samples and the ALF filter coefficients,
- derive cross-component filter coefficients for cross-component filtering, and
- generate modified filtered reconstructed chroma samples based on the reconstructed luma samples, the filtered reconstructed chroma samples, and the cross-component filter coefficients,
- wherein the image information includes a sequence parameter set (SPS), header information and an adaptation parameter set (APS) including ALF data,
- wherein the SPS includes a cross-component adaptive loop filter (CCALF) enabled flag related to whether the cross-component filtering is enabled,
- wherein the cross-component filter coefficients are derived based on the ALF data,
- wherein the header information includes a first flag related to whether the CCALF is enabled for a Cb color component of the filtered reconstructed chroma samples,
- wherein based on the determination that a value of the first flag is 1, the header information includes information related to an identifier of the APS for deriving the cross-component filter coefficients for the Cb color component,
- wherein the ALF data included in the APS for deriving the cross-component filter coefficients for the Cb color component include a Cb filter signal flag related to whether the cross-component filters for the Cb color component are signaled,
- wherein based on the Cb filter signal flag, the ALF data included in the APS for deriving the cross-component filter coefficients for the Cb color component include information related to the number of cross-component filters for the Cb color component,
- wherein based on the information related to the number of cross-component filters for the Cb color component, the ALF data included in the APS for deriving the cross-component filter coefficients for the Cb color component include information on absolute values of the cross-component filter coefficients for the Cb color component and information on signs of the cross-component filter coefficients for the Cb color component, and
- wherein the cross-component filter coefficients for the Cb color component are derived based on the information on the absolute values of the cross-component filter coefficients for the Cb color component and the information on the signs of the cross-component filter coefficients for the Cb color component.
19 more elements
An apparatus for encoding image information, the apparatus comprising:
- a memory;
- and
- at least one processor connected to the memory, the at least one processor configured to:
- generate prediction samples for a current block,
- generate prediction related information based on the prediction samples,
- generate residual samples for the current block based on the prediction samples,
- derive transform coefficients based on a transform process for the residual samples,
- derive quantized transform coefficients based on a quantization process for the transform coefficients,
- generate residual information indicating the quantized transform coefficients,
- generate reconstructed samples based on the residual information,
- generate adaptive loop filter (ALF)-related information and cross-component ALF (CCALF)-related information for the reconstructed samples, and
- encode the image information including the prediction related information, the residual information, the ALF-related information, and the CCALF-related information,
- wherein the image information includes a sequence parameter set (SPS), header information and an adaptation parameter set (APS) including ALF data,
- wherein the SPS includes a CCALF enabled flag related to whether the cross-component filtering is enabled,
- wherein the header information includes a first flag related to whether the CCALF is enabled for a Cb color component of the filtered reconstructed chroma samples,
- wherein cross-component filter coefficients are represented based on the ALF data,
- wherein based on the determination that a value of the first flag is 1, the header information includes information related to an identifier of the APS for deriving the cross-component filter coefficients for the Cb color component,
- wherein the ALF data included in the APS for deriving the cross-component filter coefficients for the Cb color component include a Cb filter signal flag related to whether cross-component filters for the Cb color component are signaled,
- wherein based on the Cb filter signal flag, the ALF data included in the APS for deriving the cross-component filter coefficients for the Cb color component include information related to the number of cross-component filters for the Cb color component,
- wherein based on the information related to the number of cross-component filters for the Cb color component, the ALF data included in the APS for deriving the cross-component filter coefficients for the Cb color component include information on absolute values of the cross-component filter coefficients for the Cb color component and information on signs of the cross-component filter coefficients for the Cb color component, and
- wherein the cross-component filter coefficients for the Cb color component are derived based on the information on the absolute values of the cross-component filter coefficients for the Cb color component and the information on the signs of the cross-component filter coefficients for the Cb color component.
18 more elements
An apparatus for a bitstream for image information image information, the apparatus comprising:
- at least one processor configured to obtain the bitstream for the image information, wherein the bitstream is generated based on generating prediction samples for a current block, generating prediction related information based on the prediction samples, generating residual samples for the current block based on the prediction samples, deriving transform coefficients based on a transform process for the residual samples, deriving quantized transform coefficients based on a quantization process for the transform coefficients, generating residual information indicating the quantized transform coefficients, generating reconstructed samples based on the residual information, generating adaptive loop filter (ALF)-related information and cross-component ALF (CCALF)-related information for the reconstructed samples, and generating the bitstream for the image information including the prediction related information, the residual information, the ALF-related information, and the CCALF-related information;
- and
- a transmitter configured to transmit data comprising the bitstream,
- wherein the image information includes a sequence parameter set (SPS), header information and an adaptation parameter set (APS) including ALF data,
- wherein the SPS includes a CCALF enabled flag related to whether the cross-component filtering is enabled,
- wherein the header information includes a first flag related to whether the CCALF is enabled for a Cb color component of the filtered reconstructed chroma samples,
- wherein cross-component filter coefficients are represented based on the ALF data,
- wherein based on the determination that a value of the first flag is 1, the header information includes information related to an identifier of the APS for deriving the cross-component filter coefficients for the Cb color component,
- wherein the ALF data included in the APS for deriving the cross-component filter coefficients for the Cb color component include a Cb filter signal flag related to whether cross-component filters for the Cb color component are signaled,
- wherein based on the Cb filter signal flag, the ALF data included in the APS for deriving the cross-component filter coefficients for the Cb color component include information related to the number of cross-component filters for the Cb color component,
- wherein based on the information related to the number of cross-component filters for the Cb color component, the ALF data included in the APS for deriving the cross-component filter coefficients for the Cb color component include information on absolute values of the cross-component filter coefficients for the Cb color component and information on signs of the cross-component filter coefficients for the Cb color component, and
- wherein the cross-component filter coefficients for the Cb color component are derived based on the information on the absolute values of the cross-component filter coefficients for the Cb color component and the information on the signs of the cross-component filter coefficients for the Cb color component.
9 more elements
Dependencies are inferred from the claim text.