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US 12,003,773 B2Granted
Transform-based video coding method, and device therefor
AssigneeLG Electronics Inc.
InventorsMoonmo Koo, Seunghwan Kim, Jaehyun Lim
Life of this patent
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Abstract
A video decoding method according to the present document comprises a step of deriving a modified transform coefficient, and the step of deriving the transform coefficient may comprise the steps of: determining whether an LFNST can be applied to the height and width of a current block on the basis of the tree type and color format of the current block; parsing an LFNST index if the LFNST can be applied; and deriving the modified transform coefficient on the basis of the LFNST index and an LFNST matrix.
Claims4
A decoding apparatus for image decoding, the decoding apparatus comprising:
- a memory;
- and
- at least one processor connected to the memory, the at least one processor configured to:
- receive information on quantized transform coefficients from a bitstream;
- derive quantized transform coefficients for a current block based on the information on the quantized transform coefficients;
- derive transform coefficients for the current block by performing a dequantization on the quantized transform coefficients;
- derive modified transform coefficients by applying a low-frequency non-separable transform (LFNST) to the transform coefficients based on an LFNST matrix related to an LFNST index;
- derive residual samples for the current block by applying an inverse primary transform on the modified transform coefficients;
- and
- generate a reconstructed picture based on the residual samples,
- wherein in a case a tree-type of the current block is a dual-tree chroma, based on a height and a width of a chroma component block for the current block being equal to 4 or more, the LFNST index is parsed, and
- wherein the height and the width of the chroma component block for the current block is determined based on a color format of the current block.
9 more elements
An encoding apparatus for image encoding, the encoding apparatus comprising:
- a memory:
- and
- at least one processor connected to the memory, the at least one processor configured to:
- derive prediction samples for a current block;
- derive residual samples for the current block based on the prediction samples;
- derive transform coefficients for the current block based on a primary transform for the residual samples;
- derive modified transform coefficients from the transform coefficients based on a low-frequency non-separable transform (LFNST) matrix for an LFNST;
- derive quantized transform coefficients for the current block by performing a quantization on the modified transform coefficients;
- and
- encode information on the quantized transform coefficients and an LFNST index related to the LFNST matrix,
- wherein in a case a tree-type of the current block is a dual-tree chroma, based on a height and a width of a chroma component block for the current block being equal to 4 or more, the LFNST index is encoded, and
- wherein the height and the width of the chroma component block for the current block is determined based on a color format of the current block.
9 more elements
An apparatus for transmitting data for an image, the apparatus comprising:
- at least one processor configured to obtain a bitstream for the image, wherein the bitstream is generated based on deriving prediction samples for a current block, deriving residual samples for the current block based on the prediction samples, deriving transform coefficients for the current block based on a primary transform for the residual samples, deriving modified transform coefficients from the transform coefficients based on a low-frequency non-separable transform (LFNST) matrix for an LFNST, deriving quantized transform coefficients for the current block by performing a quantization on the modified transform coefficients, and encoding information on the quantized transform coefficients and an LFNST index related to the LFNST matrix;
- and
- a transmitter configured to transmit the data comprising the bitstream,
- wherein in a case a tree-type of the current block is a dual-tree chroma, based on a height and a width of a chroma component block for the current block being equal to 4 or more, the LFNST index is encoded, and
- wherein the height and the width of the chroma component block for the current block is determined based on a color format of the current block.
2 more elements
Dependencies are inferred from the claim text.