Lg Electronics Inc.

Guangdong Oppo Mobile Telecommunications Corp., Ltd.

Beijing Xiaomi Mobile Software Co., Ltd.

University of Southern California

Xiaomi Inc.

Industry-academic Cooperation Foundation, Chosun University

Moonmo Koo

Jaehyun Lim

Seunghwan Kim

Mehdi Salehifar

Junghak Nam

Eunyong Son

Sehoon Yea

Jin Seong Heo

Jaewon Sung

Taesup Kim

Hyeongmoon Jang

Jiwook Jung

Bumshik Lee

Yongjoon Jeon

Seungwook Park

Kyuwoon Kim

Seethal Paluri

Jie Zhao

Medhi Salehifar

Sunmi Yoo Yoo

Ling Li

Jung Hak Nam

Jungah Choi

Amir Said

Onur Gonen Guleryuz

Jungdong Seo

Antonio Ortega

Hilmi Enes Egilmez

Seoungwook Park

An image decoding method according to the present document may comprise the steps of: if a current block is partitioned into sub-partition transform blocks, deriving a prediction sample of the current block on the basis of intra prediction mode information; determining an LFNST set including LFNST matrices on the basis of an intra prediction mode derived from the intra prediction mode information; selecting one of the LFNST matrices on the basis of the LFNST set and the LFNST index; deriving transform coefficients for the sub-partition transform blocks on the basis of the selected LFNST matrix; and deriving residual samples for the current block on the basis of the transform coefficients.

Transform-based image coding method, and device therefor

A video decoding method according to the present document comprises the steps of: deriving transform coefficients by performing de-quantization on the basis of quantized transform coefficients for a target block; deriving modified transform coefficients on the basis of an inverse reduced secondary transform (RST) of the transform coefficients; and generating a reconstructed picture on the basis of residual samples for the target block on the basis of an inverse primary transform of the modified transform coefficients, wherein an inverse RST using a transform kernel matrix is performed on transform coefficients of an upper-left 4×4 region of an 8×8 region of the target block, and modified transform coefficients of the upper-left 4×4 region, an upper-right 4×4 region, and a lower-left 4×4 region of the 8×8 region are derived through the inverse RST.

Video coding method based on secondary transform, and device therefor

An image decoding method according to this document comprises a step of deriving, for transform coefficients, modified transform coefficients on the basis of inverse secondary transform, wherein: the step of deriving the modified transform coefficients may comprise a step of deriving a transform kernel to be applied to the inverse secondary transform; on the basis of both the horizontal and vertical lengths of a target block being greater than or equal to 8 and the horizontal or vertical length being 8, the transform kernel may be set to a 64×32 matrix; and on the basis of both the horizontal and vertical lengths of the target block being 8, a 64×16 matrix sampled from the 64×32 matrix may be applied to the inverse secondary transform of the target block.

Image coding method and apparatus therefor

A method for processing a video includes determining a horizontal transform type index for a horizontal transform kernel and a vertical transform type index for a vertical transform kernel of a transform block in the video signal, determining a transform region in which a significant transform coefficient exists in the transform block based on the horizontal transform type index, the vertical transform type index, and a size of the transform block, and applying inverse-transform to the transform region based on the horizontal transform type index and the vertical transform type index. A width of the transform region is determined based on a comparison between the horizontal transform type index and a reference value and a height of the transform region is determined based on a comparison between the vertical transform type index and the reference value.

Method for processing video signal by using transform, and apparatus therefor

Embodiments of the present invention provide video signal processing methods. A video signal encoding method according to an embodiment of the present invention comprises checking a transform block including residual samples except a prediction sample from a picture of the video signal, generating transform coefficients through a transform for the residual samples of the transform block based on a size of the transform block, and performing quantization and entropy coding the transform coefficients, wherein generating the transform coefficients includes, applying a forward primary transform to each of a horizontal direction and vertical direction of the transform block including the residual samples, and not applying a forward non-separable secondary transform to the transform block to which the primary transform has been applied when the size of the transform block is smaller than or equal to 4×4, and applying the forward non-separable secondary transform to the transform block when the size of the transform block is greater than 4×4.

Methods and apparatuses for processing video signal

An image decoding method according to the present document comprises the steps of: receiving an intra-MIP syntax element for a first target block; deriving the value of the intra-MIP syntax element; setting a variable MIP flag for the preset specific area, which is the same as the area of the first target block, on the basis of the value of the intra-MIP syntax element; deriving an intra-prediction mode of the second target block on the basis of the variable MIP flag; and deriving a prediction sample of the second target block on the basis of the intra-prediction mode of the second target block.

Image coding method and device therefor

An image decoding method according to the present document comprises a step of deriving a corrected transform coefficient by applying low-frequency non-separable transform (LFNST) to a transform coefficient, wherein an LFNST set for applying the LFNST may be derived on the basis of an intra-prediction mode applied to the current block, and an LFNST matrix may be derived on the basis of the size of the current block and the LFNST set, the LFNST matrix derived as a 16×16 dimensional matrix if the width or the height of the current block is 4 and the width and the height are both 4 or greater, and the LFNST matrix derived as a 64×32 dimensional matrix if the width or the height of the current block is 8 and the width and the height are both 8 or greater. Therefore, coding performance capable of being brought by the LFNST can be maximized within the implementation complexity permitted in forthcoming standards.

Method and device for designing low-frequency non-separable transform

An image decoding method according to the present document comprises the steps of: deriving transform coefficients through inverse quantization on the basis of quantized transform coefficients for a target block; deriving modified transform coefficients on the basis of an inverse reduced secondary transform (RST) for the transform coefficients; and generating, on the basis of an inverse primary transform for the modified transform coefficients, a restoration picture based on residual samples for the target block, wherein the modified transform coefficients derived according to the inverse RST are two-dimensionally arranged according to the order of a row priority direction or a column priority direction according to an intra prediction mode to be applied to the target block.

Image coding method based on secondary transform, and device therefor

Embodiments of the present disclosure provide a method and apparatus for processing a video signal. A method for decoding a video signal according to an embodiment of the present disclosure includes obtaining a sub-block transform (SBT) flag indicating whether an SBT is applied, wherein the SBT represents a transform applied to one of sub-blocks split from a coding unit, determining a transform unit from the coding unit based on the SBT flag, determining a size value of the transform unit as a first reference value if DST-7 (Discrete Sine Transform type 7) or DCT-8 (Discrete Cosine Transform type 8) is applied and the size value of the transform unit is greater than the first reference value and less than a third reference value and determining the size value as a second reference value if DCT-2 (Discrete Cosine Transform type 2) is applied and the size value is equal to or greater than the third reference value, wherein the third reference value is greater than the second reference value and the second reference value is greater than the first reference value, obtaining transform coefficients based on the size value, and performing an inverse transform on the transform coefficients. A data processing time and the amount of data necessary for a transform can be reduced by performing coding in consideration of a region reduced according to a block size.

Method for processing image on basis of transform and device therefor

An image decoding method according to the present document may comprise the steps of: receiving image information including residual information and an LFNST index from a bitstream; deriving a transform coefficient on the basis of the residual information; deriving a flag variable related to whether LFNST is applied to a current block on the basis of the LFNST index; and performing the LFNST on the basis of the flag variable and the transform coefficient, wherein the flag variable is derived for each color component of the current block.

A video decoding method performed by a decoding apparatus includes the steps of: deriving control points (CP) for a current block; acquiring movement vectors for the CPs; deriving a sample unit movement vector in the current block on the basis of the acquired movement vectors; and deriving a prediction sample for the current block on the basis of the sample unit movement vector. According to the present invention, it is possible to effectively perform, through sample unit motion vectors, inter-prediction not only in a case where an image in the current block is plane-shifted but also in a case where there are various image distortions.

Inter prediction method and apparatus in video coding system

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.

Transform-based video coding method, and device therefor

A video decoding method according to the present document is characterized by comprising: a step for deriving transform coefficients through inverse quantization on the basis of quantized transform coefficients for a target block; a step for deriving modified transform coefficients on the basis of an inverse reduced secondary transform (RST) of the transform coefficients; and a step for generating a reconstructed picture on the basis of residual samples for the target block on the basis of an inverse primary transform of the modified transform coefficients, wherein the inverse RST using a transform kernel matrix is performed on transform coefficients of the upper-left 4×4 region of an 8×8 region of the target block, and the modified transform coefficients of the upper-left 4×4 region, upper-right 4×4 region, and lower-left 4×4 region of the 8×8 region are derived through the inverse RST.

Video coding method on basis of secondary transform, and device for same

An image decoding method according to the present document comprises a step for performing inverse first-order transform and inverse non-separable transform on a residual sample. The inverse non-separable transform is performed on the basis of a transform index indicating a predetermined transform kernel matrix, the inverse first-order transform is performed on the basis of a multiple transform selection (MTS) index indicating MTS for a horizontal transform kernel and a vertical transform kernel, and a syntax element bin string for the transform index is derived on the basis of first context information when a tree type for a split structure of a target block is not a single tree type and is derived on the basis of second context information when the tree type is the single tree type.

Transform-based image coding method and device therefor

Techniques and systems for reconstructing a video signal, which include: obtaining a transform coefficient block by performing an entropy decoding and a dequantization for a current block; deriving a secondary transform corresponding to a specific area in the transform coefficient block, wherein the specific area represents an area including a top-left block of the transform coefficient block; performing an inverse secondary transform for each of subblocks within the specific area using the secondary transform; performing an inverse primary transform for a block which the inverse secondary transform is applied to; and reconstructing the current block using a block which the primary inverse transform is applied to.

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Seoul, South Korea

Moonmo Koo