Image encoding / decoding method and apparatus, and recording medium storing bitstream

Abstract

An image decoding method and apparatus according to the present disclosure may: determine whether a geometric partitioning mode is applied to a current block on the basis of the size of the current block and predetermined threshold size information; if it is determined that the geometric partitioning mode is applied to the current block, generate a prediction block of the current block on the basis of the geometric partitioning mode; and reconstruct the current block on the basis of the prediction block.

Description

Video encoding / decoding method and device, and recording medium storing bitstream

[0001] The present invention relates to a video encoding / decoding method and device, and a recording medium storing a bitstream.

[0002] Recently, the demand for high-resolution, high-quality images, such as HD (High Definition) images and UHD (Ultra High Definition) images, is increasing in various application fields, and accordingly, high-efficiency image compression technologies are being discussed.

[0003] There are various technologies for image compression, such as inter prediction technology that predicts pixel values ​​included in the current picture from pictures before or after the current picture, intra prediction technology that predicts pixel values ​​included in the current picture using pixel information within the current picture, and entropy encoding technology that assigns short codes to values ​​with high frequency of appearance and long codes to values ​​with low frequency of appearance, and these technologies can be used to effectively compress and transmit or store image data.

[0004] The present disclosure seeks to provide a method and device for applying a geometric segmentation mode.

[0005] The present disclosure seeks to provide a method and device for signaling syntax elements related to a geometric segmentation mode.

[0006] The image decoding method and device according to the present disclosure can determine whether a geometric segmentation mode is applied to the current block based on the size of the current block and predetermined threshold size information, and, if it is determined that the geometric segmentation mode is applied to the current block, can generate a prediction block of the current block based on the geometric segmentation mode, and can restore the current block based on the prediction block.

[0007] In the video decoding method and device according to the present disclosure, the threshold size information may include at least one of a minimum GPM block size regarding a minimum size of a coding unit to which the geometric division mode can be applied, a maximum GPM block size regarding a maximum size of a coding unit to which the geometric division mode can be applied, or a ratio of a block width and a block height to which the geometric division mode can be applied.

[0008] In the image decoding method and device according to the present disclosure, the ratio of the block width and block height may be applied differently depending on the size of the current block.

[0009] In the video decoding method and device according to the present disclosure, at least one of information regarding the minimum GPM block size, information regarding the maximum GPM block size, or information regarding the ratio of the block width and block height can be signaled from a bitstream.

[0010] In the image decoding method and device according to the present disclosure, the minimum GPM block size can be derived based on a value obtained by adding a first value to a value of information about the minimum GPM block size, and the maximum GPM block size can be derived based on a value obtained by adding a second value to a value of information about the maximum GPM block size.

[0011] In the video decoding method and device according to the present disclosure, the minimum GPM block size can be derived based on a value obtained by adding a first value to a value of information about the minimum GPM block size, and the maximum GPM block size can be derived based on a value obtained by adding the first value to a value of information about the minimum GPM block size and a value of information about the maximum GPM block size.

[0012] In the image decoding method and device according to the present disclosure, the ratio of the block width and the block height can be derived based on a value obtained by adding a third value to the value of information regarding the ratio of the block width and the block height.

[0013] In the video decoding method and device according to the present disclosure, in the step of generating a prediction block of the current block, the number of blending area sizes available to the current block can be determined based on the size of the current block.

[0014] In the image decoding method and device according to the present disclosure, in the step of generating a prediction block of the current block, application of at least one of a plurality of detailed modes based on the geometric segmentation mode may be restricted depending on the size of the current block.

[0015] In the video decoding method and device according to the present disclosure, the plurality of detailed modes may include at least one of an adaptive blending processing mode that performs blending processing by selectively using any one of a plurality of blending region sizes, a GPM Intra mode that applies intra prediction to at least one of a plurality of partitions within the current block, a GPM MMVD mode that applies MMVD (merge with motion vector difference) to at least one of the plurality of partitions, a GPM TM mode that applies TM (template matching) to at least one of the plurality of partitions, or a GPM Affine mode that performs affine inter prediction for each of the plurality of partitions.

[0016] The video encoding method and device according to the present disclosure can determine whether a geometric segmentation mode is applied to the current block based on the size of the current block and predetermined threshold size information, and, if it is determined that the geometric segmentation mode is applied to the current block, generate a prediction block of the current block based on the geometric segmentation mode, generate a residual block of the current block based on the prediction block, derive transform coefficients of the current block based on the residual block, and encode residual information regarding the transform coefficients.

[0017] A computer-readable digital storage medium storing encoded video / image information that causes a device according to the present disclosure to perform a method according to the present disclosure is provided.

[0018] A computer-readable digital storage medium storing video / image information generated by a method according to the present disclosure is provided.

[0019] A method and device for transmitting video / image information generated by a method according to the present disclosure are provided.

[0020] According to the present disclosure, image compression efficiency can be improved by adaptively utilizing a geometric segmentation mode by considering the size of the current block and predetermined threshold size information.

[0021] According to the present disclosure, threshold size information can be effectively signaled.

[0022] FIG. 1 illustrates a video / image coding system according to the present disclosure.

[0023] FIG. 2 is a schematic block diagram of an encoding device to which an embodiment of the present disclosure can be applied and in which encoding of a video / image signal is performed.

[0024] FIG. 3 is a schematic block diagram of a decoding device to which an embodiment of the present disclosure can be applied and in which decoding of a video / image signal is performed.

[0025] FIG. 4 illustrates an image decoding method performed by a decoding device (300) as an embodiment according to the present disclosure.

[0026] FIG. 5 illustrates a schematic configuration of a decoding device (300) that performs a decoding method according to the present disclosure.

[0027] FIG. 6 illustrates an encoding method performed by an encoding device (200) as an embodiment according to the present disclosure.

[0028] FIG. 7 illustrates a schematic configuration of an encoding device (200) that performs an encoding method according to the present disclosure.

[0029] FIG. 8 illustrates an example of a content streaming system to which embodiments of the present disclosure can be applied.

[0030] The image decoding method and device according to the present disclosure can determine whether a geometric segmentation mode is applied to the current block based on the size of the current block and predetermined threshold size information, and, if it is determined that the geometric segmentation mode is applied to the current block, can generate a prediction block of the current block based on the geometric segmentation mode, and can restore the current block based on the prediction block.

[0031] In the video decoding method and device according to the present disclosure, the threshold size information may include at least one of a minimum GPM block size regarding a minimum size of a coding unit to which the geometric division mode can be applied, a maximum GPM block size regarding a maximum size of a coding unit to which the geometric division mode can be applied, or a ratio of a block width and a block height to which the geometric division mode can be applied.

[0032] In the image decoding method and device according to the present disclosure, the ratio of the block width and block height may be applied differently depending on the size of the current block.

[0033] In the video decoding method and device according to the present disclosure, at least one of information regarding the minimum GPM block size, information regarding the maximum GPM block size, or information regarding the ratio of the block width and block height can be signaled from a bitstream.

[0034] In the image decoding method and device according to the present disclosure, the minimum GPM block size can be derived based on a value obtained by adding a first value to a value of information about the minimum GPM block size, and the maximum GPM block size can be derived based on a value obtained by adding a second value to a value of information about the maximum GPM block size.

[0035] In the video decoding method and device according to the present disclosure, the minimum GPM block size can be derived based on a value obtained by adding a first value to a value of information about the minimum GPM block size, and the maximum GPM block size can be derived based on a value obtained by adding the first value to a value of information about the minimum GPM block size and a value of information about the maximum GPM block size.

[0036] In the image decoding method and device according to the present disclosure, the ratio of the block width and the block height can be derived based on a value obtained by adding a third value to the value of information regarding the ratio of the block width and the block height.

[0037] In the video decoding method and device according to the present disclosure, in the step of generating a prediction block of the current block, the number of blending area sizes available to the current block can be determined based on the size of the current block.

[0038] In the image decoding method and device according to the present disclosure, in the step of generating a prediction block of the current block, application of at least one of a plurality of detailed modes based on the geometric segmentation mode may be restricted depending on the size of the current block.

[0039] In the video decoding method and device according to the present disclosure, the plurality of detailed modes may include at least one of an adaptive blending processing mode that performs blending processing by selectively using any one of a plurality of blending region sizes, a GPM Intra mode that applies intra prediction to at least one of a plurality of partitions within the current block, a GPM MMVD mode that applies MMVD (merge with motion vector difference) to at least one of the plurality of partitions, a GPM TM mode that applies TM (template matching) to at least one of the plurality of partitions, or a GPM Affine mode that performs affine inter prediction for each of the plurality of partitions.

[0040] The video encoding method and device according to the present disclosure can determine whether a geometric segmentation mode is applied to the current block based on the size of the current block and predetermined threshold size information, and, if it is determined that the geometric segmentation mode is applied to the current block, generate a prediction block of the current block based on the geometric segmentation mode, generate a residual block of the current block based on the prediction block, derive transform coefficients of the current block based on the residual block, and encode residual information regarding the transform coefficients.

[0041] A computer-readable digital storage medium storing encoded video / image information that causes a device according to the present disclosure to perform a method according to the present disclosure is provided.

[0042] A computer-readable digital storage medium storing video / image information generated by a method according to the present disclosure is provided.

[0043] A method and device for transmitting video / image information generated by a method according to the present disclosure are provided.

[0044] The present disclosure may be modified in various ways and encompasses numerous embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present disclosure to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present disclosure. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0045] While terms such as "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present disclosure, a first component could be referred to as a "second component," and similarly, a second component could also be referred to as a "first component." The term "and / or" includes a combination of multiple related items described herein or any of multiple related items described herein.

[0046] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0047] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0048] The present disclosure relates to video / image coding. For example, the methods / embodiments disclosed in this specification can be applied to methods disclosed in the versatile video coding (VVC) standard. In addition, the methods / embodiments disclosed in this specification can be applied to methods disclosed in the essential video coding (EVC) standard, the AOMedia Video 1 (AV1) standard, the second generation of audio video coding standard (AVS2), or the next generation of video / image coding standards (e.g., H.267 or H.268).

[0049] This specification presents various embodiments of video / image coding, and unless otherwise stated, the embodiments may be performed in combination with each other.

[0050] In this specification, a video may refer to a set of images over time. A picture generally refers to a unit representing one image at a specific time point, and a slice / tile is a unit that constitutes one or more pictures in coding. A slice / tile may include one or more coding tree units (CTUs). A picture may be composed of one or more slices / tiles. A tile is a rectangular area consisting of multiple CTUs within a specific tile column and a specific tile row of a picture. A tile column is a rectangular area of ​​CTUs that has a height equal to the height of the picture and a width specified by the syntax requirements of the picture parameter set. A tile row is a rectangular area of ​​CTUs that has a height specified by the picture parameter set and a width equal to the width of the picture. CTUs within a tile are arranged consecutively according to the CTU raster scan, while tiles within a picture may be arranged consecutively according to the tile raster scan. A slice may contain an integer number of complete tiles or an integer number of contiguous complete CTU rows within a picture, which may be exclusively contained within a single NAL unit. Meanwhile, a picture may be divided into two or more subpictures. A subpicture may be a rectangular region of one or more slices within a picture.

[0051] A pixel, or pel, can refer to the smallest unit that constitutes a picture (or image). Additionally, the term "sample" can be used as a counterpart to a pixel. A sample can generally represent a pixel or a pixel value, and can represent only the pixel / pixel value of the luminance component, or only the pixel / pixel value of the chrominance component.

[0052] A unit may represent a basic unit of image processing. A unit may include at least one of a specific region of a picture and information related to the region. One unit may include one luma block and two chroma (e.g., cb, cr) blocks. In some cases, the term "unit" may be used interchangeably with terms such as "block" or "area." In general, an MxN block may include a set (or array) of samples (or sample array) or transform coefficients consisting of M columns and N rows.

[0053] As used herein, "A or B" can mean "only A," "only B," or "both A and B." In other words, as used herein, "A or B" can be interpreted as "A and / or B." For example, as used herein, "A, B or C" can mean "only A," "only B," "only C," or "any combination of A, B and C."

[0054] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "A and / or B." Accordingly, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0055] In this specification, "at least one of A and B" may mean "only A", "only B" or "both A and B". Additionally, in this specification, the expressions "at least one of A or B" or "at least one of A and / or B" may be interpreted identically to "at least one of A and B".

[0056] Additionally, in this specification, “at least one of A, B and C” can mean “only A,” “only B,” “only C,” or “any combination of A, B and C.” Additionally, “at least one of A, B or C” or “at least one of A, B and / or C” can mean “at least one of A, B and C.”

[0057] Additionally, parentheses used herein may mean "for example." Specifically, when "prediction (intra-prediction)" is indicated, "intra-prediction" may be suggested as an example of "prediction." In other words, "prediction" in this specification is not limited to "intra-prediction," and "intra-prediction" may be suggested as an example of "prediction." Furthermore, even when "prediction (i.e., intra-prediction)" is indicated, "intra-prediction" may be suggested as an example of "prediction."

[0058] Technical features individually described in a single drawing in this specification may be implemented individually or simultaneously.

[0059] FIG. 1 illustrates a video / image coding system according to the present disclosure.

[0060] Referring to FIG. 1, a video / image coding system may include a first device (source device) and a second device (receiving device).

[0061] A source device can transmit encoded video / image information or data to a receiving device via a digital storage medium or a network in the form of a file or streaming. The source device may include a video source, an encoding device, and a transmitting device. The receiving device may include a receiving device, a decoding device, and a renderer. The encoding device may be referred to as a video / image encoding device, and the decoding device may be referred to as a video / image decoding device. The transmitter may be included in the encoding device. The receiver may be included in the decoding device. The renderer may include a display unit, and the display unit may be configured as a separate device or an external component.

[0062] A video source may obtain video / images through a process of capturing, synthesizing, or generating video / images. The video source may include a video / image capture device and / or a video / image generation device. The video / image capture device may include one or more cameras, a video / image archive containing previously captured video / images, etc. The video / image generation device may include a computer, a tablet, a smartphone, etc., and may (electronically) generate video / images. For example, a virtual video / image may be generated through a computer, etc., in which case the video / image capture process may be replaced by a process of generating related data.

[0063] An encoding device can encode input video / images. The encoding device can perform a series of procedures, such as prediction, transformation, and quantization, to improve compression and coding efficiency. The encoded data (encoded video / image information) can be output in the form of a bitstream.

[0064] The transmission unit can transmit encoded video / image information or data output in the form of a bitstream to the receiving unit of a receiving device via a digital storage medium or network in the form of a file or streaming. The digital storage medium can include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. The transmission unit can include an element for generating a media file via a predetermined file format and an element for transmission via a broadcasting / communication network. The receiving unit can receive / extract the bitstream and transmit it to a decoding device.

[0065] The decoding device can decode the video / image by performing a series of procedures such as inverse quantization, inverse transformation, and prediction corresponding to the operation of the encoding device.

[0066] The renderer can render decoded video / images. The rendered video / images can be displayed through the display unit.

[0067] FIG. 2 is a schematic block diagram of an encoding device to which an embodiment of the present disclosure can be applied and in which encoding of a video / image signal is performed.

[0068] Referring to FIG. 2, the encoding device (200) may be configured to include an image partitioner (210), a prediction unit (predictor) 220, a residual processor (residual processor) 230, an entropy encoder (entropy encoder) 240, an adder (adder) 250, a filter (filter) 260, and a memory (memory) 270. The prediction unit (220) may include an inter prediction unit (221) and an intra prediction unit (222). The residual processor (230) may include a transformer (transformer) 232, a quantizer (quantizer) 233, a dequantizer (dequantizer) 234, and an inverse transformer (inverse transformer) 235. The residual processing unit (230) may further include a subtractor (231). The addition unit (250) may be called a reconstructor or a recontructed block generator. The image segmentation unit (210), the prediction unit (220), the residual processing unit (230), the entropy encoding unit (240), the addition unit (250), and the filtering unit (260) described above may be configured by one or more hardware components (e.g., an encoding device chipset or processor) according to an embodiment. In addition, the memory (270) may include a decoded picture buffer (DPB) and may be configured by a digital storage medium. The hardware component may further include the memory (270) as an internal / external component.

[0069] The image segmentation unit (210) can segment an input image (or picture, frame) input to the encoding device (200) into one or more processing units. For example, the processing unit may be called a coding unit (CU). In this case, the coding unit may be recursively segmented from a coding tree unit (CTU) or a largest coding unit (LCU) according to a QTBTTT (Quad-tree binary-tree ternary-tree) structure.

[0070] For example, a single coding unit may be split into multiple coding units with deeper depths based on a quad-tree structure, a binary tree structure, and / or a ternary structure. In this case, for example, the quad-tree structure may be applied first, and the binary tree structure and / or the ternary structure may be applied later. Alternatively, the binary tree structure may be applied before the quad-tree structure. The coding procedure according to the present specification may be performed based on the final coding unit that is no longer split. In this case, based on coding efficiency according to image characteristics, etc., the largest coding unit may be used directly as the final coding unit, or, if necessary, the coding unit may be recursively split into coding units of lower depths, and the coding unit with the optimal size may be used as the final coding unit. Here, the coding procedure may include procedures such as prediction, transformation, and restoration, which will be described later.

[0071] As another example, the processing unit may further include a prediction unit (PU) or a transform unit (TU). In this case, the prediction unit and the transform unit may each be split or partitioned from the final coding unit described above. The prediction unit may be a unit of sample prediction, and the transform unit may be a unit for deriving a transform coefficient and / or a unit for deriving a residual signal from a transform coefficient.

[0072] The term "unit" may be used interchangeably with terms such as "block" or "area" depending on the case. In general, an MxN block can represent a set of samples or transform coefficients consisting of M columns and N rows. A sample can generally represent a pixel or a pixel value, and can represent only the pixel / pixel value of the luminance component, or only the pixel / pixel value of the chrominance component. A sample can be used as a term corresponding to a pixel or pel in a picture (or image).

[0073] The encoding device (200) can generate a residual signal (residual block, residual sample array) by subtracting a prediction signal (prediction block, prediction sample array) output from an inter prediction unit (221) or an intra prediction unit (222) from an input video signal (original block, original sample array), and the generated residual signal is transmitted to a conversion unit (232). In this case, a unit that subtracts a prediction signal (prediction block, prediction sample array) from an input video signal (original block, original sample array) within the encoding device (200) may be called a subtraction unit (231).

[0074] The prediction unit (220) can perform a prediction on a block to be processed (hereinafter, referred to as a current block) and generate a predicted block including prediction samples for the current block. The prediction unit (220) can determine whether intra prediction or inter prediction is applied on a current block or CU basis. The prediction unit (220) can generate various information related to prediction, such as prediction mode information, as described later in the description of each prediction mode, and transmit the information to the entropy encoding unit (240). The information related to prediction can be encoded by the entropy encoding unit (240) and output in the form of a bitstream.

[0075] The intra prediction unit (222) can predict the current block by referring to samples in the current picture. The referenced samples may be located in the neighborhood of the current block, or may be located a certain distance away from the current block, depending on the prediction mode. In intra prediction, the prediction modes may include one or more non-directional modes and multiple directional modes. The non-directional mode may include at least one of a DC mode or a planar mode. The directional mode may include 33 directional modes or 65 directional modes depending on the degree of detail in the prediction direction. However, this is only an example, and a greater or lesser number of directional modes may be used depending on the settings. The intra prediction unit (222) may also determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring blocks.

[0076] The inter prediction unit (221) can derive a prediction block for a current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. At this time, in order to reduce the amount of motion information transmitted in the inter prediction mode, the motion information can be predicted in units of blocks, subblocks, or samples based on the correlation of motion information between neighboring blocks and the current block. The motion information can include a motion vector and a reference picture index. The motion information can further include inter prediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, the neighboring block can include a spatial neighboring block existing in the current picture and a temporal neighboring block existing in the reference picture. The reference picture including the reference block and the reference picture including the temporal neighboring block may be the same or different. The above temporal neighboring blocks may be called collocated reference blocks, collocated CUs (colCUs), etc., and the reference pictures including the temporal neighboring blocks may be called collocated pictures (colPic). For example, the inter prediction unit (221) may construct a motion information candidate list based on the neighboring blocks, and generate information indicating which candidate is used to derive the motion vector and / or reference picture index of the current block. Inter prediction may be performed based on various prediction modes, and for example, in the case of skip mode and merge mode, the inter prediction unit (221) may use the motion information of the neighboring blocks as the motion information of the current block. In the case of skip mode, unlike the merge mode, a residual signal may not be transmitted.In the motion vector prediction (MVP) mode, the motion vector of the surrounding blocks is used as a motion vector predictor, and the motion vector of the current block can be indicated by signaling the motion vector difference.

[0077] The prediction unit (220) can generate a prediction signal based on various prediction methods described below. For example, the prediction unit can apply intra prediction or inter prediction for prediction of a single block, and can also apply intra prediction and inter prediction simultaneously. This can be called combined inter and intra prediction (CIIP) mode. In addition, the prediction unit can be based on an intra block copy (IBC) prediction mode or a palette mode for prediction of a block. The IBC prediction mode or palette mode can be used for content image / video coding such as games, such as screen content coding (SCC). IBC basically performs prediction within the current picture, but can be performed similarly to inter prediction in that it derives a reference block within the current picture. That is, IBC can utilize at least one of the inter prediction techniques described herein. Palette mode can be viewed as an example of intra coding or intra prediction. When the palette mode is applied, sample values ​​within a picture can be signaled based on information about the palette table and palette index. The prediction signal generated through the prediction unit (220) can be used to generate a restoration signal or a residual signal.

[0078] The transform unit (232) can apply a transform technique to the residual signal to generate transform coefficients. For example, the transform technique can include at least one of a Discrete Cosine Transform (DCT), a Discrete Sine Transform (DST), a Karhunen-Loeve Transform (KLT), a Graph-Based Transform (GBT), or a Conditionally Non-linear Transform (CNT). Here, GBT refers to a transform obtained from a graph when the relationship information between pixels is expressed as a graph. CNT refers to a transform obtained based on generating a prediction signal using all previously restored pixels. In addition, the transform process can be applied to a pixel block having a square size and the same size, or can be applied to a block of a non-square variable size.

[0079] The quantization unit (233) quantizes the transform coefficients and transmits them to the entropy encoding unit (240), and the entropy encoding unit (240) can encode the quantized signal (information about the quantized transform coefficients) and output it as a bitstream. The information about the quantized transform coefficients can be called residual information. The quantization unit (233) can rearrange the quantized transform coefficients in a block form into a one-dimensional vector form based on the coefficient scan order, and can also generate information about the quantized transform coefficients based on the quantized transform coefficients in the one-dimensional vector form.

[0080] The entropy encoding unit (240) can perform various encoding methods such as exponential Golomb, context-adaptive variable length coding (CAVLC), context-adaptive binary arithmetic coding (CABAC), etc. The entropy encoding unit (240) can also encode information necessary for video / image restoration (e.g., values ​​of syntax elements, etc.) together or separately from quantized transform coefficients.

[0081] Encoded information (e.g., encoded video / image information) can be transmitted or stored in the form of a bitstream in units of NAL (network abstraction layer) units. The video / image information may further include information on various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). In addition, the video / image information may further include general constraint information. In the present specification, information and / or syntax elements transmitted / signaled from an encoding device to a decoding device may be included in the video / image information. The video / image information may be encoded through the above-described encoding procedure and included in the bitstream. The bitstream may be transmitted via a network or stored in a digital storage medium. Here, the network may include a broadcasting network and / or a communication network, and the digital storage medium may include various storage media, such as a USB, SD, CD, DVD, Blu-ray, HDD, or SSD. The signal output from the entropy encoding unit (240) may be configured as an internal / external element of the encoding device (200) by a transmitting unit (not shown) and / or a storing unit (not shown), or the transmitting unit may be included in the entropy encoding unit (240).

[0082] The quantized transform coefficients output from the quantization unit (233) can be used to generate a prediction signal. For example, by applying inverse quantization and inverse transformation to the quantized transform coefficients through the inverse quantization unit (234) and the inverse transform unit (235), a residual signal (residual block or residual samples) can be reconstructed. The addition unit (250) can generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the reconstructed residual signal to the prediction signal output from the inter prediction unit (221) or the intra prediction unit (222). When there is no residual for the block to be processed, such as when skip mode is applied, the predicted block can be used as a reconstructed block. The addition unit (250) may be called a reconstructor or a reconstructed block generation unit. The generated restoration signal can be used for intra prediction of the next processing target block within the current picture, and can also be used for inter prediction of the next picture after filtering as described below. Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture encoding and / or restoration process.

[0083] The filtering unit (260) can improve subjective / objective picture quality by applying filtering to the restoration signal. For example, the filtering unit (260) can apply various filtering methods to the restoration picture to generate a modified restoration picture, and store the modified restoration picture in the memory (270), specifically, in the DPB of the memory (270). The various filtering methods can include deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc. The filtering unit (260) can generate various information regarding filtering and transmit it to the entropy encoding unit (240). The information regarding filtering can be encoded by the entropy encoding unit (240) and output in the form of a bitstream.

[0084] The modified restored picture transmitted to the memory (270) can be used as a reference picture in the inter prediction unit (221). Through this, when inter prediction is applied, the encoding device can avoid prediction mismatch between the encoding device (200) and the decoding device, and can also improve encoding efficiency.

[0085] The DPB of the memory (270) can store the modified restored picture to be used as a reference picture in the inter prediction unit (221). The memory (270) can store motion information of a block from which motion information is derived (or encoded) within the current picture and / or motion information of blocks within a picture that has already been restored. The stored motion information can be transferred to the inter prediction unit (221) to be used as motion information of a spatial neighboring block or motion information of a temporal neighboring block. The memory (270) can store restored samples of restored blocks within the current picture and transfer them to the intra prediction unit (222).

[0086] FIG. 3 is a schematic block diagram of a decoding device to which an embodiment of the present disclosure can be applied and in which decoding of a video / image signal is performed.

[0087] Referring to FIG. 3, the decoding device (300) may be configured to include an entropy decoder (310), a residual processor (320), a predictor (330), an adder (340), a filter (350), and a memory (360). The predictor (330) may include an inter-prediction unit (332) and an intra-prediction unit (331). The residual processor (320) may include a dequantizer (321) and an inverse transformer (321).

[0088] The entropy decoding unit (310), residual processing unit (320), prediction unit (330), addition unit (340), and filtering unit (350) described above may be configured by a single hardware component (e.g., a decoding device chipset or processor) depending on the embodiment. In addition, the memory (360) may include a decoded picture buffer (DPB) and may be configured by a digital storage medium. The hardware component may further include the memory (360) as an internal / external component.

[0089] When a bitstream including video / image information is input, the decoding device (300) can restore the image corresponding to the process in which the video / image information is processed in the encoding device of FIG. 2. For example, the decoding device (300) can derive units / blocks based on block division-related information obtained from the bitstream. The decoding device (300) can perform decoding using a processing unit applied in the encoding device. Accordingly, the processing unit of decoding may be a coding unit, and the coding unit may be divided from a coding tree unit or a maximum coding unit according to a quad tree structure, a binary tree structure, and / or a ternary tree structure. One or more transform units may be derived from the coding unit. Then, the restored image signal decoded and output through the decoding device (300) can be reproduced through a reproduction device.

[0090] The decoding device (300) can receive a signal output from the encoding device of FIG. 2 in the form of a bitstream, and the received signal can be decoded through the entropy decoding unit (310). For example, the entropy decoding unit (310) can parse the bitstream to derive information (e.g., video / image information) necessary for image restoration (or picture restoration). The video / image information may further include information on various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). In addition, the video / image information may further include general constraint information. The decoding device can decode the picture further based on the information on the parameter set and / or the general constraint information. The signaling / received information and / or syntax elements described later in this specification can be decoded through the decoding procedure and obtained from the bitstream. For example, the entropy decoding unit (310) can decode information in a bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and output the values ​​of syntax elements required for image restoration and the quantized values ​​of transform coefficients for residuals. More specifically, the CABAC entropy decoding method receives a bin corresponding to each syntax element in the bitstream, determines a context model using information of the syntax element to be decoded and decoding information of the surrounding and decoding target blocks or information of symbols / bins decoded in the previous step, and predicts the occurrence probability of the bin according to the determined context model to perform arithmetic decoding of the bin to generate a symbol corresponding to the value of each syntax element.At this time, the CABAC entropy decoding method can update the context model using the information of the decoded symbol / bin for the context model of the next symbol / bin after determining the context model. Information regarding prediction among the information decoded by the entropy decoding unit (310) is provided to the prediction unit (inter prediction unit (332) and intra prediction unit (331)), and residual values ​​on which entropy decoding is performed by the entropy decoding unit (310), i.e., quantized transform coefficients and related parameter information, can be input to the residual processing unit (320). The residual processing unit (320) can derive a residual signal (residual block, residual samples, residual sample array). In addition, information regarding filtering among the information decoded by the entropy decoding unit (310) can be provided to the filtering unit (350). Meanwhile, a receiving unit (not shown) that receives a signal output from an encoding device may be further configured as an internal / external element of a decoding device (300), or the receiving unit may be a component of an entropy decoding unit (310).

[0091] Meanwhile, a decoding device according to the present specification may be called a video / video / picture decoding device, and the decoding device may be divided into an information decoding device (video / video / picture information decoding device) and a sample decoding device (video / video / picture sample decoding device). The information decoding device may include the entropy decoding unit (310), and the sample decoding device may include at least one of the inverse quantization unit (321), the inverse transformation unit (322), the addition unit (340), the filtering unit (350), the memory (360), the inter prediction unit (332), and the intra prediction unit (331).

[0092] The inverse quantization unit (321) can inverse quantize the quantized transform coefficients and output the transform coefficients. The inverse quantization unit (321) can rearrange the quantized transform coefficients into a two-dimensional block form. In this case, the rearrangement can be performed based on the coefficient scanning order performed in the encoding device. The inverse quantization unit (321) can perform inverse quantization on the quantized transform coefficients using quantization parameters (e.g., quantization step size information) and obtain transform coefficients.

[0093] In the inverse transform unit (322), the transform coefficients are inversely transformed to obtain a residual signal (residual block, residual sample array).

[0094] The prediction unit (320) can perform a prediction on the current block and generate a predicted block including prediction samples for the current block. The prediction unit (320) can determine whether intra-prediction or inter-prediction is applied to the current block based on the information regarding the prediction output from the entropy decoding unit (310), and can determine a specific intra / inter-prediction mode.

[0095] The prediction unit (320) can generate a prediction signal based on various prediction methods described below. For example, the prediction unit (320) can apply intra prediction or inter prediction for prediction of a single block, and can also apply intra prediction and inter prediction simultaneously. This can be called combined inter and intra prediction (CIIP) mode. In addition, the prediction unit can be based on an intra block copy (IBC) prediction mode or a palette mode for prediction of a block. The IBC prediction mode or palette mode can be used for content image / video coding such as games, such as screen content coding (SCC). IBC basically performs prediction within the current picture, but can be performed similarly to inter prediction in that it derives a reference block within the current picture. That is, IBC can utilize at least one of the inter prediction techniques described herein. Palette mode can be viewed as an example of intra coding or intra prediction. When palette mode is applied, information about the palette table and palette index may be included and signaled in the video / image information.

[0096] The intra prediction unit (331) can predict the current block by referring to samples within the current picture. The referenced samples may be located in the neighborhood of the current block, or may be located a certain distance away from the current block, depending on the prediction mode. In intra prediction, the prediction modes may include one or more non-directional modes and multiple directional modes. The intra prediction unit (331) may also determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring blocks.

[0097] The inter prediction unit (332) can derive a prediction block for the current block based on a reference block (reference sample array) specified by a motion vector on a reference picture. At this time, in order to reduce the amount of motion information transmitted in the inter prediction mode, the motion information can be predicted in units of blocks, subblocks, or samples based on the correlation of the motion information between the neighboring blocks and the current block. The motion information can include a motion vector and a reference picture index. The motion information can further include inter prediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of inter prediction, the neighboring blocks can include spatial neighboring blocks existing in the current picture and temporal neighboring blocks existing in the reference picture. For example, the inter prediction unit (332) can construct a motion information candidate list based on the neighboring blocks, and derive the motion vector and / or reference picture index of the current block based on the received candidate selection information. Inter prediction can be performed based on various prediction modes, and information about the prediction can include information indicating an inter prediction mode for the current block.

[0098] The addition unit (340) can generate a restoration signal (restored picture, restoration block, restoration sample array) by adding the acquired residual signal to the prediction signal (prediction block, prediction sample array) output from the prediction unit (including the inter-prediction unit (332) and / or intra-prediction unit (331)). When there is no residual for the block to be processed, such as when skip mode is applied, the prediction block can be used as the restoration block.

[0099] The addition unit (340) may be referred to as a restoration unit or restoration block generation unit. The generated restoration signal may be used for intra prediction of the next processing target block within the current picture, may be output after filtering as described below, or may be used for inter prediction of the next picture. Meanwhile, LMCS (luma mapping with chroma scaling) may be applied during the picture decoding process.

[0100] The filtering unit (350) can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit (350) can apply various filtering methods to the restored picture to generate a modified restored picture, and transmit the modified restored picture to the memory (360), specifically, to the DPB of the memory (360). The various filtering methods can include deblocking filtering, sample adaptive offset, adaptive loop filter, bilateral filter, etc.

[0101] The (corrected) reconstructed picture stored in the DPB of the memory (360) can be used as a reference picture in the inter prediction unit (332). The memory (360) can store motion information of a block from which motion information is derived (or decoded) in the current picture and / or motion information of blocks in a picture that has already been reconstructed. The stored motion information can be transferred to the inter prediction unit (332) to be used as motion information of a spatial neighboring block or motion information of a temporal neighboring block. The memory (360) can store reconstructed samples of reconstructed blocks in the current picture and transfer them to the intra prediction unit (331).

[0102] In this specification, the embodiments described in the filtering unit (260), the inter prediction unit (221), and the intra prediction unit (222) of the encoding device (200) can be applied to the filtering unit (350), the inter prediction unit (332), and the intra prediction unit (331) of the decoding device (300) in the same or corresponding manner, respectively.

[0103] FIG. 4 illustrates a decoding method performed by a decoding device (300) as an embodiment according to the present disclosure.

[0104] Referring to FIG. 4, it is possible to determine whether the geometric division mode is applied to the current block (S400).

[0105] In inter prediction based on geometric partitioning modes, the complexity of determining a suitable geometric partition shape for prediction can increase. Therefore, the present disclosure proposes a method for specifying the size and shape of a block that maximizes compression efficiency while minimizing the added complexity when performing inter prediction based on geometric partitioning modes.

[0106] Whether the geometric segmentation mode is applied to the current block can be determined based on the size of the current block and a predetermined threshold size information.

[0107] The size of the current block can be defined by width (CbWidth) and / or height (CbHeight).

[0108] The threshold size information may include at least one of the minimum GPM block size (GEO_MIN_CU_SIZE), the maximum GPM block size (GEO_MAX_CU_SIZE), or the ratio of block width to block height (GEO_WH_RATIO).

[0109] The minimum GPM block size may indicate the minimum size of a coding unit to which the geometric partitioning mode can be applied. The maximum GPM block size may indicate the maximum size of a coding unit to which the geometric partitioning mode can be applied. Here, the minimum size and / or maximum size of the coding unit may be defined as at least one of the width or height of the coding unit. The ratio of the block width to the block height may refer to the ratio of the width and height of a block to which the geometric partitioning mode can be applied.

[0110] If a predetermined condition between the size of the current block and the threshold size information is satisfied, it may be determined that the geometric segmentation mode is applied to the current block. The predetermined condition may include at least one of the first to sixth conditions described below.

[0111] (1st condition) The width of the current block is greater than or equal to the minimum GPM block size.

[0112] (2nd condition) The height of the current block is greater than or equal to the minimum GPM block size.

[0113] (3rd condition) The width of the current block is less than or equal to the maximum GPM block size.

[0114] (Condition 4) The height of the current block is less than or equal to the maximum GPM block size.

[0115] (Condition 5) The width of the current block is less than or equal to the product of the ratio of the width and height of the GPM block and the height of the current block.

[0116] (Condition 6) The height of the current block is less than or equal to the product of the ratio of the width and height of the GPM block and the width of the current block.

[0117] For example, the value of the minimum GPM block size can be any one of 4, 8, or 16, and can be greater than or equal to the minimum coding unit size. In addition, the value of the maximum GPM block size can be any one of 32, 64, 128, or 256, and can be less than or equal to the maximum coding unit size. In addition, the ratio of the block width to the block height can be any one of 2, 4, 8, or 16.

[0118] At least one of the minimum GPM block size, the maximum GPM block size, or the ratio of the block width to the block height may be encoded in the encoding device and signaled to the decoding device via the bitstream. Alternatively, at least one of the minimum GPM block size, the maximum GPM block size, or the ratio of the block width to the block height may be predefined as the same value in the encoding device and the decoding device.

[0119] The ratio of block width to block height can be expressed as either a ratio of N:1 or 1:N. In other words, in the fifth condition, the ratio of block width to block height can be expressed as N:1. Alternatively, in the sixth condition, the ratio of block width to block height can be expressed as 1:N.

[0120] When applying the geometric division mode to the current block, the ratio of the block width and block height described above may be applied differently depending on the size of the current block.

[0121] Let's look at a case where 4 is used as the ratio of block width to block height that supports geometric partitioning mode. In this case, assuming that the minimum GPM block size is 8 and the maximum GPM block size is 64, geometric partitioning mode can be applied to block sizes of 8x8, 8x16, 8x32, 32x8, 16x8, 16x16, 16x32, 16x64, 64x16, 32x16, 32x32, 32x64, 64x32, and 64x64.

[0122] Alternatively, let's look at the case where 8 is used as the ratio of block width to block height that supports the geometric partitioning mode. In this case, assuming that the minimum GPM block size is 8 and the maximum GPM block size is 64, the geometric partitioning mode can be applied to block sizes of 8x8, 8x16, 8x32, 8x64, 64x8, 32x8, 16x8, 16x16, 16x32, 16x64, 64x16, 32x16, 32x32, 32x64, 64x32, and 64x64.

[0123] As the difference between the minimum and maximum GPM block sizes increases, the number of additional blocks to which the geometric partitioning mode can be applied may increase, depending on the ratio of the block width to the block height that supports the geometric partitioning mode. Therefore, in consideration of the trade-off between complexity and encoding efficiency, the ratio of the block width to the block height that supports the geometric partitioning mode can be applied differently depending on the current block size.

[0124] For example, for 128xN or Nx128 blocks, a ratio of 4 can be used for the block width to block height, and for the remaining block sizes where the geometric partitioning mode can be applied, a ratio of 8 can be used for the block width to block height.

[0125] Alternatively, for 4xN or Nx4 blocks, a ratio of 4 can be used for the block width to block height, and for the remaining block sizes where the geometry subdivision mode can be applied, a ratio of 8 can be used for the block width to block height.

[0126] In addition, in terms of considering the trade-off between complexity and encoding efficiency, the minimum GPM block size, the maximum GPM block size, and the ratio of block width to block height supporting the geometric partitioning mode can be applied differently depending on the size of the image to be encoded and decoded, and the frame rate.

[0127] For example, if the size of the image currently being encoded and decoded is greater than or equal to 1920x1080, the minimum GPM block size can be 8, the maximum GPM block size can be 64, and the ratio of the block width to the block height that supports the geometric partitioning mode can be 8.

[0128] On the other hand, if the size of the image currently being encoded and decoded is smaller than 1920x1080, the minimum GPM block size can be 4, the maximum GPM block size can be 32, and the ratio of block width to block height supporting geometric segmentation mode can be 4.

[0129] The above threshold size information can be signaled in the upper-level syntax of the bitstream. The upper-level syntax can include at least one of a Sequence Parameter Set (SPS), a Picture Parameter Set (PPS), a Picture Header (PH), or a Slice Header (SH). However, for convenience of explanation, it is assumed below that the threshold size information is signaled in the SPS.

[0130] Table 1 shows a syntax table in which syntax elements for minimum GPM block size, maximum GPM block size, and ratio of block width to block height are signaled, and Table 2 shows the semantics of the corresponding syntax elements.

[0131] seq_parameter_set_rbsp() {Descriptor… log2_gpm_min_cu_size_minus2ue(v)log2_gpm_max_cu_size_minus5ue(v)log2_gpm_wh_cu_ratio_minus2ue(v)…}

[0132] log2_gpm_min_cu_size_minus2plus 2 specifies the minimum luma coding block size for geometric partitioning mode. The value range of log2_gpm_min_cu_size_minus2 shall be in the range of log2_min_luma_coding_block_size_minus2 to CtbLog2SizeY - MinCbLog2SizeY, inclusive.The variables GeoMinCbLog2Size and GeoMinCbSize are derived as follows:GeoMinCbLog2Size = log2_gpm_min_cu_size_minus2 + 2GeoMinCbSize = 1 << GeoMinCbLog2Sizelog2_gpm_max_cu_size_minus5plus 5 specifies the maximum luma coding block size for geometric partitioning mode. The value range of log2_gpm_max_cu_size_minus5 shall be in the range of 0 to sps_log2_ctu_size_minus5, inclusive.The variables GeoMaxCbLog2Size and GeoMaxCbSize are derived as follows:GeoMaxCbLog2Size = log2_gpm_max_cu_size_minus5 + 5GeoMaxCbSize = 1 << GeoMaxCbLog2Sizelog2_gpm_wh_cu_ratio_minus2plus 2 specifies the maximum ratio of CbWidth / CbHeight or CbHeight / CbWidth for geometric partitioning mode.The value range of log2_gpm_wh_cu_ratio_minus2 shall be in the range 0 to 2.The variables GeoMaxRatioLog2Size and GeoMaxRatio are derived as follows:GeoMaxRatioLog2Size = log2_gpm_wh_cu_ratio_minus2 +2GeoMaxRatio = 1 << GeoMaxRatioLog2Size.

[0133] As shown in Table 1 and Table 2, the minimum GPM block size, maximum GPM block size, and the ratio of block width to block height supporting the geometric partitioning mode can be signaled as a Log2 value. The remaining value after subtracting a predefined value from the Log2 value can be signaled. In this case, for the minimum GPM block size, the predefined value can be 2 or 3. For the maximum GPM block size, the predefined value can be 5 or 6. For the ratio of block width to block height, the predefined value can be 2.

[0134] log2_gpm_min_cu_size_minus2 may be information about the minimum GPM block size. The minimum GPM block size can be derived based on the value of log2_gpm_min_cu_size_minus2 plus a predefined value (e.g., 2).

[0135] log2_gpm_max_cu_size_minus5 may be information about the maximum GPM block size. The maximum GPM block size can be derived based on the value of log2_gpm_max_cu_size_minus5 plus a predefined value (e.g., 5).

[0136] log2_gpm_wh_cu_ratio_minus2 can be information about the ratio of block width to block height that supports geometric partitioning mode. The ratio of block width to block height can be derived based on the value obtained by adding a predefined value (e.g., 2) to log2_gpm_wh_cu_ratio_minus2.

[0137] Table 3 shows a syntax table in which syntax elements for minimum GPM block size, maximum GPM block size, and ratio of block width to block height are signaled, and Table 4 shows the semantics of the corresponding syntax elements.

[0138] seq_parameter_set_rbsp() {Descriptor… log2_gpm_min_cu_size_minus2ue(v)log2_gpm_diff_max_min_sizeue(v)log2_gpm_wh_cu_ratioue(v)…}

[0139] log2_gpm_min_cu_size_minus2plus 2 specifies the minimum luma coding block size for geometric partitioning mode. The value range of log2_gpm_min_cu_size_minus2 shall be in the range of log2_min_luma_coding_block_size_minus2 to CtbLog2SizeY - MinCbLog2SizeY, inclusive.The variables GeoMinCbLog2Size and GeoMinCbSize are derived as follows:GeoMinCbLog2Size = log2_gpm_min_cu_size_minus2 + 2GeoMinCbSize = 1 << GeoMinCbLog2Sizelog2_gpm_diff_max_min_sizespecifies the default difference between the base 2 logarithm of the maximum size (width or height) and the minimum size (width or height) in luma samples of a luma coding block that can be coded geometric partitioning mode.The variables GeoMaxCbLog2Size and GeoMaxCbSize are derived as follows:GeoMaxCbLog2Size = GeoMinCbLog2Size + log2_gpm_diff_max_min_size GeoMaxCbSize = 1 << GeoMaxCbLog2Sizelog2_gpm_wh_cu_ratiospecifies the maximum ratio of CbWidth / CbHeight or CbHeight / CbWidth for geometric partitioning mode.The value range of log2_gpm_wh_cu_ratio shall be in the range 1 to 5.The variable GeoMaxRatio is derived as follows:GeoMaxRatio = 1 << log2_gpm_wh_cu_ratio.

[0140] As shown in Tables 3 and 4, the minimum GPM block size, maximum GPM block size, and the ratio of block width to block height supporting geometric partitioning mode can be signaled as Log2 values.

[0141] Here, for the minimum GPM block size, it can be signaled as the remainder value obtained by subtracting a predefined value from the Log2 value. Here, the predefined value can be 2 or 3. The maximum GPM block size can be signaled in the form of the difference value between the Log2 value of the maximum GPM block size and the Log2 value of the minimum GPM block size. Unlike in Tables 1 and 2, the ratio of the block width to the block height can be signaled as the Log2 value of the ratio of the block width to the height.

[0142] log2_gpm_min_cu_size_minus2 may be information about the minimum GPM block size. The minimum GPM block size can be derived based on the value of log2_gpm_min_cu_size_minus2 plus a predefined value (e.g., 2).

[0143] log2_gpm_diff_max_min_size may be information about the maximum GPM block size. The maximum GPM block size can be derived based on the value of log2_gpm_diff_max_min_size plus the log2 value of the minimum GPM block size.

[0144] log2_gpm_wh_cu_ratio can be information about the ratio of block width to block height that supports geometric partitioning mode. Based on the value of log2_gpm_wh_cu_ratio, the ratio of block width to block height can be derived.

[0145] Table 3 describes a method for signaling information about the minimum GPM block size before information about the maximum GPM block size, but this is only an example. For example, information about the maximum GPM block size could be signaled before information about the minimum GPM block size. In this case, the minimum GPM block size could be signaled in the form of the difference between the Log2 value of the maximum GPM block size and the Log2 value of the minimum GPM block size.

[0146] In other words, after signaling log2_gpm_max_cu_size_minus5, log2_gpm_diff_max_min_size can be signaled. In this case, the maximum GPM block size (GeoMaxCbSize) can be derived as in the following mathematical expression 1, and the minimum GPM block size (GeoMinCbSize) can be derived as in the following mathematical expression 2.

[0147] [Mathematical Formula 1]

[0148] GeoMaxCbLog2Size = log2_gpm_max_cu_size_minus5 + 5

[0149] GeoMaxCbSize = 1 << GeoMaxCbLog2Size

[0150] [Equation 2]

[0151] GeoMinCbLog2Size = GeoMaxCbLog2Size - log2_gpm_diff_max_min_size

[0152] GeoMinCbSize = 1 << GeoMinCbLog2Size

[0153] Table 5 shows a syntax table in which syntax elements for minimum GPM block size, maximum GPM block size, and ratio of block width to block height are signaled, and Table 6 shows the semantics of the corresponding syntax elements.

[0154] seq_parameter_set_rbsp() {Descriptor… log2_diff_min_cu_size_for_gpmue(v)log2_gpm_diff_max_min_sizeue(v)log2_gpm_wh_cu_ratioue(v)…}

[0155] log2_diff_min_cu_size_for_gpmspecifies the default difference between the base 2 logarithm of the minimum size (width or height) in luma samples of a luma coding block and the base 2 logarithm of the minimum luma coding block size (width or height) for geometric partitioning mode. The value range of log2_diff_min_cu_size_for_gpm shall be in the range of 0 to CtbLog2SizeY - MinCbLog2SizeY, inclusive.The variables GeoMinCbLog2Size and GeoMinCbSize are derived as follows:GeoMinCbLog2Size = log2_diff_min_cu_size_for_gpm + MinCbLog2SizeY (##)GeoMinCbSize = 1 << GeoMinCbLog2Size (##)log2_gpm_diff_max_min_sizespecifies the default difference between the base 2 logarithm of the maximum size (width or height) and the minimum size (width or height) in luma samples of a luma coding block that can be coded geometric partitioning mode.The variables GeoMaxCbLog2Size and GeoMaxCbSize are derived as follows:GeoMaxCbLog2Size = GeoMinCbLog2Size + log2_gpm_diff_max_min_size (##)GeoMaxCbSize = 1 << GeoMaxCbLog2Size (##)log2_gpm_wh_cu_ratiospecifies the maximum ratio of CbWidth / CbHeight or CbHeight / CbWidth for geometric partitioning mode. The value range of log2_gpm_wh_cu_ratio shall be in the range 1 to 5.The variable GeoMaxRatio is derived as follows:GeoMaxRatio = 1 << log2_gpm_wh_cu_ratio (##).

[0156] As shown in Tables 5 and 6, the minimum GPM block size, maximum GPM block size, and the ratio of block width to block height that supports the geometric partitioning mode can be signaled as Log2 values. In this case, the minimum GPM block size can be signaled as a difference value with the Log2 value of the minimum coding unit size supported by the current sequence.

[0157] log2_gpm_min_cu_size_minus2 may be information about the minimum GPM block size. The minimum GPM block size can be derived based on the value obtained by adding the Log2 value of the minimum coding unit size to log2_gpm_min_cu_size_minus2.

[0158] Meanwhile, the signaling method and derivation method for the maximum GPM block size and the ratio of block width to block height are as shown in Tables 3 and 4.

[0159] Tables 1 to 6 describe cases where SPS is used for signaling and parsing, but this is only an example. It can be signaled and parsed in one or more of the higher-level syntaxes such as PPS, PH, and SH. At this time, the value can be stored or used by overriding it with the value of the higher-level syntax that is ultimately signaled. Depending on the characteristics of the image, the block size and / or the ratio of the block width and block height to which the geometric segmentation mode can be applied may vary. In addition, when the threshold size information is encoded / decoded through the higher-level syntax, the optimal block size and width / height ratio that can maximize the compression efficiency according to the geometric segmentation mode can be applied.

[0160] Referring to FIG. 4, a prediction block of the current block can be generated based on the geometric segmentation mode (S410).

[0161] If it is determined that the geometric partitioning mode is applied to the current block, the current block may be partitioned into multiple partitions. At least one of the partitions may have a geometric partitioning shape other than a rectangle.

[0162] When the geometric partitioning mode is applied, various detailed modes can be applied based on the geometric partitioning mode. Here, examples of the detailed modes include an adaptive blending process mode, a GPM intra mode that applies intra prediction to at least one of a plurality of partitions, a GPM MMVD mode that applies merge mode with motion vector difference (MMVD) to at least one of a plurality of partitions, a GPM TM mode that applies TM (template matching) to at least one of a plurality of partitions, and a GPM Affine mode that performs affine inter prediction for each of a plurality of partitions. At least one of the above-described detailed modes can be additionally used in inter prediction based on the geometric partitioning mode.

[0163] The application of the adaptive blending processing mode may be restricted depending on the size of the current block. In particular, depending on the size of the current block to which the geometric partitioning mode is applied and the size of the blending area, the pixel area on which the adaptive blending processing operates may be restricted or exceeded, which may result in a reduction in encoding efficiency according to the geometric partitioning. The adaptive blending processing mode may be a mode that selectively uses any one of a plurality of blending area sizes to perform blending processing on the divided partition.

[0164] For example, if the current block size is 4xN or Nx4, the geometric segmentation-based prediction and compensation may not work or the prediction performance may decrease if the blending region size is greater than or equal to W. W can be any integer. For example, W can be 4. Accordingly, if the current block size is less than or equal to 4xN or Nx4, the adaptive blending processing mode may not be applied. For other sizes, the adaptive blending processing mode may be applied.

[0165] Alternatively, the number of blending region sizes applied in the adaptive blending processing mode can be reduced based on the size of the current block.

[0166] For example, if the size of the current block is any one of 4xN, Nx4, 8xN, or Nx8, the number of applicable blending region sizes can be reduced. For example, the number of initial blending region sizes can be configured as 5, such as {τ / 4, τ / 2, τ, 2τ, 4τ}. At this time, if the size of the current block is any one of 4xN, Nx4, 8xN, or Nx8, the number of applicable blending region sizes can be reduced to 3, such as {τ / 2, τ, 2τ}.

[0167] Alternatively, an adaptive blending processing mode can be applied by fixing the number of blending region sizes to 1 based on the size of the current block. In this case, the applied blending region size can be τ.

[0168] However, the constraints of the adaptive blending processing mode (e.g., block size condition) and the number of blending region sizes are only examples, and may be defined with other conditions and numbers.

[0169] In an encoding device and a decoding device performing an adaptive blending processing mode according to the present disclosure, signaling and parsing methods of candidate indices may be different based on the size of the current block and the number of blending region sizes.

[0170] The GPM intra mode can be adaptively applied based on the size of the current block. The GPM intra mode can be a mode that performs encoding / decoding using an intra prediction mode for at least one of a plurality of partitions.

[0171] Intra-mode can generally occur more frequently in small-sized blocks than in large-sized blocks. Therefore, the method proposed in this disclosure can limit the application of GPM intra-mode to large-sized blocks.

[0172] For example, if the current block is a 128xN or Nx128 block, the application of the GPM intra mode may be restricted. In this case, signaling and parsing of syntax related to the GPM intra mode may be skipped. However, the block size to which the application of the GPM intra mode is restricted is not limited to 128xN and Nx128. For example, if the product of the width and height of the current block is greater than M, the application of the GPM intra mode may be restricted. Here, the value of M may be a predefined integer, and may be optionally defined as any one of the values ​​such as 1024, 2048, 4096, and 8192.

[0173] Depending on the size of the current block, the application of GPM MMVD mode or GPM TM mode may be limited. GPM MMVD mode may be a method of directly signaling additional correction values ​​for motion vector information using the MMVD method when performing prediction using the geometric partitioning mode. GPM TM mode may be a method of using template matching (TM) to correct motion vector information in the same way in the encoder / decoder when performing prediction using the geometric partitioning mode.

[0174] In GPM MMVD mode, since additional compensation values ​​for motion vector information are directly signaled using the MMVD method, the signaled bits may act as signaling overhead when the current block size is small. Therefore, the application of GPM MMVD mode can be restricted to small blocks depending on the current block size.

[0175] For example, if the current block size is 4xN or Nx4 block, the application of the GPM MMVD mode may be restricted, and the signaling and parsing process for the same may be skipped. However, the block size restricting the application of the GPM MMVD mode is not limited to 4xN and Nx4. If the product of the width and height of the current block is less than K, the application of the GPM MMVD mode may be restricted. At this time, the value of K may be a predefined integer, and may be selectively defined as one of the values ​​such as 32, 64, and 128. If the application of the GPM MMVD mode is restricted, the application of the GPM TM mode may also be restricted.

[0176] The application of the GPM Affine mode may be limited depending on the size of the current block. The GPM Affine mode may be a mode that uses the Affine mode to predict each of multiple partitions based on geometric partitioning. In this case, whether the GPM Affine mode is applied to the current block may be determined based on whether the current block size corresponds to a block size to which the Affine mode is applicable.

[0177] For example, if the Affine mode is restricted to be applicable when the width or height of the block is greater than or equal to 8, the GPM Affine mode can be applied when the width or height of the current block is greater than or equal to 8.

[0178] Depending on the current block size, the application of the Regression-based blending mode may be limited. Regression-based blending mode performs blending processing by generating a regression model for blocks to which the geometric segmentation mode is applied, without using existing predefined blending values.

[0179] For example, if the width and height of the current block are less than 8, the application of the regression-based blending mode may be restricted. Otherwise, the regression-based blending mode may be applicable.

[0180] Through the aforementioned method, the application of geometric partitioning mode-based detailed modes can be restricted or simplified based on the current block size. This can reduce the signaling and parsing processes required to indicate the application of specific detailed modes that have relatively little or no impact on compression efficiency for the current block size.

[0181] Referring to FIG. 4, the current block can be restored based on the predicted block of the current block (S430).

[0182] The current block can be reconstructed based on the prediction block and residual block of the current block. Transform coefficients can be derived based on residual information signaled from the bitstream, and at least one of inverse quantization or inverse transformation can be performed on the transform coefficients to generate a residual block.

[0183] FIG. 5 illustrates a schematic configuration of a decoding device (300) that performs a decoding method according to the present disclosure.

[0184] Referring to FIG. 5, the decoding device (300) may include a GPM determination unit (500), a prediction block generation unit (510), and a restoration unit (520). The GPM determination unit (500) and the prediction block generation unit (510) may be provided in the inter prediction unit (332) of FIG. 3.

[0185] The GPM decision unit (500) can perform a decision process on whether to apply the geometric segmentation mode according to S400. The prediction block generation unit (510) can perform a prediction block generation process according to S410. The restoration unit (520) can perform a current block restoration process according to S420.

[0186] FIG. 6 illustrates an encoding method performed by an encoding device (200) as an embodiment according to the present disclosure.

[0187] Referring to FIG. 6, it is possible to determine whether the geometric segmentation mode is applied to the current block (S400). The method for determining whether the geometric segmentation mode is applied is as described with reference to FIG. 4.

[0188] Referring to FIG. 6, if it is determined that a geometric segmentation mode is applied to the current block, a prediction block of the current block can be generated based on the geometric segmentation mode (S610). In the process of generating a prediction block based on the geometric segmentation mode, at least one of the detailed modes based on the geometric segmentation mode may be additionally applied or its application may be restricted. This is as discussed with reference to FIG. 4.

[0189] Referring to FIG. 6, transform coefficients of the current block can be derived based on the residual block of the current block (S620). The residual block of the current block can be generated based on the prediction block generated in S610. The transform coefficients can be derived by performing at least one of transformation or quantization on the residual block.

[0190] Referring to FIG. 6, a bitstream can be generated by encoding residual information regarding the transform coefficients of the current block (S630).

[0191] FIG. 7 illustrates a schematic configuration of an encoding device (200) that performs an encoding method according to the present disclosure.

[0192] Referring to FIG. 7, the encoding device (200) may include a GPM determination unit (700), a prediction block generation unit (710), a transform coefficient derivation unit (720), and a residual information encoding unit (730).

[0193] The GPM determination unit (700) and the prediction block generation unit (710) may be provided in the inter prediction unit (221) of FIG. 2. The transform coefficient derivation unit (720) may be provided in the residual processing unit (230) of FIG. 2. The residual information encoding unit (730) may be provided in the entropy encoding unit (240) of FIG. 2.

[0194] The GPM decision unit (700) can perform a decision process on whether to apply the geometric segmentation mode according to S600. The prediction block generation unit (710) can perform a prediction block generation process according to S610. The transform coefficient derivation unit (720) can perform a transform coefficient derivation process according to S620. The residual information encoding unit (730) can perform a residual information encoding process according to S630.

[0195] In the embodiments described above, the methods are described based on a flowchart as a series of steps or blocks. However, the embodiments are not limited to the order of the steps, and some steps may occur in a different order or simultaneously with other steps described above. Furthermore, those skilled in the art will understand that the steps depicted in the flowchart are not exclusive, and other steps may be included, or one or more steps in the flowchart may be deleted without affecting the scope of the embodiments of this document.

[0196] The method according to the embodiments of the present document described above can be implemented in the form of software, and the encoding device and / or decoding device according to the present document can be included in a device that performs image processing, such as a TV, a computer, a smartphone, a set-top box, a display device, etc.

[0197] When the embodiments in this document are implemented as software, the above-described method can be implemented as a module (process, function, etc.) that performs the above-described function. The module can be stored in memory and executed by a processor. The memory can be internal or external to the processor and can be connected to the processor by various well-known means. The processor can include an application-specific integrated circuit (ASIC), another chipset, logic circuit, and / or data processing device. The memory can include a read-only memory (ROM), a random access memory (RAM), flash memory, a memory card, a storage medium, and / or other storage devices. That is, the embodiments described in this document can be implemented and performed on a processor, a microprocessor, a controller, or a chip. For example, the functional units illustrated in each drawing can be implemented and performed on a computer, a processor, a microprocessor, a controller, or a chip. In this case, information for implementation (e.g., information on instructions) or an algorithm can be stored on a digital storage medium.

[0198] In addition, the decoding device and encoding device to which the embodiment(s) of the present specification are applied may be included in a multimedia broadcasting transmitting and receiving device, a mobile communication terminal, a home cinema video device, a digital cinema video device, a surveillance camera, a video conversation device, a real-time communication device such as a video communication, a mobile streaming device, a storage medium, a camcorder, a video-on-demand (VoD) service providing device, an OTT (Over the top video) device, an Internet streaming service providing device, a three-dimensional (3D) video device, a VR (virtual reality) device, an AR (argumente reality) device, a video phone video device, a transportation terminal (ex. a vehicle (including an autonomous vehicle) terminal, an airplane terminal, a ship terminal, etc.), and a medical video device, and may be used to process a video signal or a data signal. For example, the OTT (Over the top video) device may include a game console, a Blu-ray player, an Internet-connected TV, a home theater system, a smartphone, a tablet PC, a DVR (Digital Video Recorder), etc.

[0199] In addition, the processing method to which the embodiment(s) of the present specification are applied can be produced in the form of a computer-executable program and can be stored in a computer-readable recording medium. Multimedia data having a data structure according to the embodiment(s) of the present specification can also be stored in a computer-readable recording medium. The computer-readable recording medium includes all types of storage devices and distributed storage devices in which computer-readable data is stored. The computer-readable recording medium can include, for example, a Blu-ray disc (BD), a universal serial bus (USB), a ROM, a PROM, an EPROM, an EEPROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device. In addition, the computer-readable recording medium includes a medium implemented in the form of a carrier wave (e.g., transmission via the Internet). In addition, a bitstream generated by an encoding method can be stored in a computer-readable recording medium or transmitted via a wired or wireless communication network.

[0200] Additionally, the embodiments of the present disclosure may be implemented as a computer program product by program code, and the program code may be executed on a computer by the embodiments of the present disclosure. The program code may be stored on a computer-readable carrier.

[0201] FIG. 8 illustrates an example of a content streaming system to which embodiments of the present disclosure can be applied.

[0202] Referring to FIG. 8, a content streaming system to which the embodiment(s) of the present specification are applied may largely include an encoding server, a streaming server, a web server, a media storage, a user device, and a multimedia input device.

[0203] The encoding server compresses content input from multimedia input devices such as smartphones, cameras, and camcorders into digital data, generates a bitstream, and transmits it to the streaming server. Alternatively, if multimedia input devices such as smartphones, cameras, and camcorders directly generate bitstreams, the encoding server may be omitted.

[0204] The above bitstream can be generated by an encoding method or a bitstream generation method to which the embodiment(s) of the present specification are applied, and the streaming server can temporarily store the bitstream during the process of transmitting or receiving the bitstream.

[0205] The streaming server transmits multimedia data to a user device based on a user request via a web server, and the web server acts as an intermediary to inform the user of available services. When a user requests a desired service from the web server, the web server transmits the request to the streaming server, and the streaming server transmits the multimedia data to the user. At this time, the content streaming system may include a separate control server, in which case the control server controls commands / responses between each device within the content streaming system.

[0206] The streaming server can receive content from a media repository and / or an encoding server. For example, when receiving content from the encoding server, the content can be received in real time. In this case, to provide a smooth streaming service, the streaming server can store the bitstream for a certain period of time.

[0207] Examples of the user devices may include mobile phones, smart phones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation devices, slate PCs, tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, smart glasses, HMDs), digital TVs, desktop computers, digital signage, etc.

[0208] Each server within the above content streaming system can be operated as a distributed server, in which case data received from each server can be processed in a distributed manner.

[0209] The claims set forth in this specification may be combined in various ways. For example, the technical features of the method claims of this specification may be combined and implemented as a device, and the technical features of the device claims of this specification may be combined and implemented as a method. Furthermore, the technical features of the method claims and the technical features of the device claims of this specification may be combined and implemented as a device, and the technical features of the method claims and the technical features of the device claims of this specification may be combined and implemented as a method.

Claims

1. A step of determining whether a geometric segmentation mode is applied to the current block based on the size of the current block and a predetermined threshold size information; If it is determined that the geometric segmentation mode is applied to the current block, a step of generating a prediction block of the current block based on the geometric segmentation mode; and A method comprising the step of restoring the current block based on the predicted block.

2. In paragraph 1, A method wherein the threshold size information includes at least one of a minimum GPM block size regarding a minimum size of a coding unit to which the geometric division mode can be applied, a maximum GPM block size regarding a maximum size of a coding unit to which the geometric division mode can be applied, or a ratio of a block width and a block height to which the geometric division mode can be applied.

3. In paragraph 2, A method in which the ratio of the block width and block height is applied differently depending on the size of the current block.

4. In paragraph 2, A method in which at least one of information about the minimum GPM block size, information about the maximum GPM block size, or information about the ratio of the block width and block height is signaled from a bitstream.

5. In paragraph 4, The above minimum GPM block size is derived based on a value obtained by adding a first value to the value of information about the above minimum GPM block size, A method in which the above maximum GPM block size is derived based on a value obtained by adding a second value to the value of information about the above maximum GPM block size.

6. In paragraph 4, The above minimum GPM block size is derived based on a value obtained by adding a first value to the value of information about the above minimum GPM block size, The above maximum GPM block size is derived based on a value obtained by adding the first value to the value of the information about the minimum GPM block size and a value of the information about the maximum GPM block size.

7. In paragraph 4, A method in which the ratio of the block width and block height is derived based on a value obtained by adding a third value to the value of information regarding the ratio of the block width and block height.

8. In paragraph 1, A method wherein, in the step of generating a prediction block of the current block, the number of blending area sizes available to the current block is determined based on the size of the current block.

9. In paragraph 1, In the step of generating a prediction block of the current block, A method in which application of at least one of a plurality of detailed modes based on the geometric division mode is restricted depending on the size of the current block.

10. In paragraph 9, A method according to claim 1, wherein the plurality of detailed modes include at least one of an adaptive blending processing mode that selectively performs blending processing using any one of a plurality of blending region sizes, a GPM Intra mode that applies intra prediction to at least one of a plurality of partitions within the current block, a GPM MMVD mode that applies MMVD (merge with motion vector difference) to at least one of the plurality of partitions, a GPM TM mode that applies TM (template matching) to at least one of the plurality of partitions, or a GPM Affine mode that performs affine inter prediction for each of the plurality of partitions.

11. A step of determining whether a geometric segmentation mode is applied to the current block based on the size of the current block and a predetermined threshold size information; If it is determined that the geometric segmentation mode is applied to the current block, a step of generating a prediction block of the current block based on the geometric segmentation mode; A step of generating a residual block of the current block based on the prediction block; A step of deriving transform coefficients of the current block based on the residual block; and A method comprising a step of encoding residual information regarding the above transform coefficients.

12. A computer-readable storage medium storing a bitstream generated by the method according to Article 11.

13. A step of obtaining a bitstream for image information; wherein the bitstream is generated based on a step of determining whether a geometric segmentation mode is applied to the current block based on a size of the current block and predetermined threshold size information, a step of generating a prediction block of the current block based on the geometric segmentation mode when it is determined that the geometric segmentation mode is applied to the current block, a step of generating a residual block of the current block based on the prediction block, a step of deriving transform coefficients of the current block based on the residual block, and a step of encoding residual information regarding the transform coefficients, and A method comprising the step of transmitting data including the bitstream.

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