Transform-based image coding method and apparatus therefor
AssigneeLG Electronics Inc.
InventorsMoonmo Koo, Jaehyun Lim, Seunghwan Kim
Life of this patent
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Abstract
An image decoding method according to the present document comprises the steps of: deriving a transform coefficient for a current block on the basis of residual information; deriving a residual sample by applying, to the transform coefficient, at least one of LFNST and MTS; and generating a reconstructed picture on the basis of the residual samples, wherein the LFNST is performed on the basis of an LFNST index indicating an LFNST kernel, the MTS is performed on the basis of an MTS index indicating an MTS kernel, and the LFNST index may be parsed before the MTS index.
Claims13
An image decoding method performed by a decoding apparatus, the method comprising:
- receiving residual information from a bitstream;
- deriving transform coefficients for a current block based on the residual information;
- deriving residual samples by applying at least one of LFNST and MTS to the transform coefficients;
- and
- generating a reconstructed picture based on the residual samples,
- wherein the LFNST is performed based on an LFNST index related to an LFNST kernel;
- wherein the MTS is performed based on an MTS index related to an MTS kernel;
- and
- wherein the LFNST index is parsed before the MTS index.
An image encoding method performed by an encoding apparatus, the method comprising:
- deriving prediction samples for a current block;
- deriving residual samples for the current block based on the prediction sample;
- deriving transform coefficients by applying at least one of LFNST and MTS for the residual samples;
- and
- encoding quantized residual information and at least one of an LFNST index related to an LFNST kernel and an MTS index related to an MTS kernel,
- wherein the LFNST index is signaled before the MTS index.
A non-transitory computer-readable digital storage medium which stores a bitstream generated by a method, the image decoding method comprising:
- deriving prediction samples for a current block;
- deriving residual samples for the current block based on the prediction sample;
- deriving transform coefficients by applying at least one of LFNST and MTS for the residual samples;
- and
- encoding quantized residual information and at least one of an LFNST index related to an LFNST kernel and an MTS index related to an MTS kernel to generate the bitstream, wherein the LFNST index is signaled before the MTS index.
Dependencies are inferred from the claim text.