WO2021112479A1 - Image coding method based on sub picture-related information and rectangular slice-related information in video or image coding system - Google Patents

Abstract

According to the disclosure of the present document, sub picture-related information can be signaled on the basis of CTU delta absolute value information for a lower right CTU index of a sub picture, and accordingly, effects of reducing the number of bits and increasing an overall coding efficiency can be derived.

Description

An image coding method based on information related to a subpicture and information related to a rectangular slice in a video or image coding system

This document relates to video/image coding technology, and more particularly, to a video coding method based on information related to a subpicture and information related to a rectangular slice in a video or video coding system.

Recently, demand for high-resolution, high-quality video/image such as 4K or 8K or higher UHD (Ultra High Definition) video/image is increasing in various fields. As the video/image data becomes high-resolution and high-quality, the amount of information or bits transmitted relatively increases compared to the existing video/image data. In the case of storing video/image data using this method, transmission cost and storage cost are increased.

In addition, recently, interest and demand for immersive media such as VR (Virtual Reality), AR (Artificial Realtiy) content or holograms are increasing, and video/images having different image characteristics from real images such as game images. broadcasting is on the rise.

Accordingly, a high-efficiency video/image compression technology is required to effectively compress, transmit, store, and reproduce high-resolution and high-quality video/image information having various characteristics as described above.

According to an embodiment of the present document, a method and apparatus for increasing video/image coding efficiency are provided.

According to an embodiment of the present document, a method and apparatus for efficiently performing coding through picture segmentation are provided.

According to an embodiment of the present document, a method and an apparatus for signaling information related to a subpicture are provided.

According to an embodiment of the present document, there is provided a method and apparatus for signaling information related to the layout of a subpicture based on absolute CTU delta value information for the lower right CTU index of the subpicture.

According to an embodiment of the present document, a method and an apparatus for signaling information related to a rectangular slice are provided.

According to an embodiment of the present document, there is provided a method and apparatus for signaling information related to the layout of a rectangular slice based on absolute tile delta value information for the lower right tile index of the rectangular slice.

According to an embodiment of the present document, a video/image decoding method performed by a decoding apparatus is provided.

According to an embodiment of the present document, there is provided a decoding apparatus for performing video/image decoding.

According to an embodiment of the present document, a video/image encoding method performed by an encoding apparatus is provided.

According to an embodiment of the present document, an encoding apparatus for performing video/image encoding is provided.

According to one embodiment of this document, there is provided a computer-readable digital storage medium in which encoded video/image information generated according to the video/image encoding method disclosed in at least one of the embodiments of this document is stored.

According to an embodiment of this document, encoded information or encoded video/image information causing the decoding apparatus to perform the video/image decoding method disclosed in at least one of the embodiments of this document is stored; A storage medium is provided.

According to an embodiment of the present document, overall video/image compression efficiency may be increased.

According to an embodiment of the present document, coding may be efficiently performed through picture division.

According to an embodiment of this document, information related to a sub-picture may be signaled.

According to an embodiment of this document, information related to the layout of the subpicture may be signaled based on absolute CTU delta value information for the lower right CTU index of the subpicture.

According to an embodiment of this document, information related to a rectangular slice may be signaled.

According to an embodiment of the present document, information related to the layout of the rectangular slice may be signaled based on absolute tile delta value information for the lower right tile index of the rectangular slice.

1 schematically shows an example of a video/image coding system to which embodiments of this document can be applied.

2 is a diagram schematically illustrating a configuration of a video/image encoding apparatus to which embodiments of the present document may be applied.

3 is a diagram schematically illustrating a configuration of a video/image decoding apparatus to which embodiments of the present document may be applied.

4 exemplarily shows a hierarchical structure for a coded video/image.

5 to 8 show an embodiment in which a picture is divided into slices and tiles.

9 shows an embodiment in which a picture is divided into slices (sub pictures) and tiles.

10 and 11 schematically show an example of a video/image encoding method and related components according to embodiment(s) of this document.

12 and 13 schematically show an example of a video/image decoding method and related components according to an embodiment of the present document.

14 shows an example of a content streaming system to which embodiments disclosed in this document can be applied.

Since this document may have various changes and may have various embodiments, specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present document to a specific embodiment. Terms commonly used herein are used only to describe specific embodiments, and are not intended to limit the technical spirit of the present document. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, and includes one or more other features or It is to be understood that the existence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded in advance.

On the other hand, each configuration in the drawings described in this document is shown independently for convenience of description regarding different characteristic functions, and does not mean that each configuration is implemented as separate hardware or separate software. For example, two or more components among each component may be combined to form one component, or one component may be divided into a plurality of components. Embodiments in which each component is integrated and/or separated are also included in the scope of the present document without departing from the essence of this document.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the present document will be described in more detail. Hereinafter, the same reference numerals may be used for the same components in the drawings, and repeated descriptions of the same components may be omitted.

1 schematically shows an example of a video/image coding system to which embodiments of this document can be applied.

Referring to FIG. 1 , a video/image coding system may include a first apparatus (source device) and a second apparatus (receive device). The source device may transmit encoded video/image information or data in the form of a file or streaming to the receiving device through a digital storage medium or a network.

The source device may include a video source, an encoding apparatus, and a transmission unit. The receiving device may include a receiving unit, a decoding apparatus, and a renderer. The encoding apparatus may be referred to as a video/image encoding apparatus, and the decoding apparatus may be referred to as a video/image decoding apparatus. 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 external component.

A video source may acquire a video/image through a process of capturing, synthesizing, or generating a video/image. A video source may include a video/image capture device and/or a video/image generating device. A video/image capture device may include, for example, one or more cameras, a video/image archive containing previously captured video/images, and the like. A video/image generating device may include, for example, a computer, tablet, and smart phone, and may (electronically) generate a video/image. For example, a virtual video/image may be generated through a computer, etc. In this case, the video/image capturing process may be substituted for the process of generating related data.

The encoding device may encode the input video/image. The encoding apparatus may perform a series of procedures such as prediction, transformation, and quantization for compression and coding efficiency. The encoded data (encoded video/image information) may be output in the form of a bitstream.

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

The decoding apparatus may 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 apparatus.

The renderer may render the decoded video/image. The rendered video/image may be displayed through the display unit.

This article is about video/image coding. For example, a method/embodiment disclosed in this document may be applied to a method disclosed in a versatile video coding (VVC) standard. In addition, the method/embodiment disclosed in this document is an essential video coding (EVC) standard, AOMedia Video 1 (AV1) standard, 2nd generation of audio video coding standard (AVS2), or a next-generation video/video coding standard (ex. H.267). or H.268, etc.).

This document presents various embodiments related to video/image coding, and unless otherwise stated, the embodiments may be combined with each other.

In this document, a video may mean a set of a series of images according to the passage of time. A picture generally refers to a unit representing one image in a specific time period, and a slice/tile is a unit constituting a part of a picture in coding. A slice/tile may include one or more coding tree units (CTUs). One picture may consist of one or more slices/tiles. A tile is a rectangular region of CTUs within a particular tile column and a particular tile row in a picture. The tile column is a rectangular region of CTUs, the rectangular region has a height equal to the height of the picture, and the width may be specified by syntax elements in a picture parameter set (The tile column is a rectangular region of CTUs having a height equal to the height of the picture and a width specified by syntax elements in the picture parameter set). The tile row is a rectangular region of CTUs, the rectangular region has a height specified by syntax elements in a picture parameter set, and the width may be equal to the width of the picture (The tile row is a rectangular region of CTUs) having a height specified by syntax elements in the picture parameter set and a width equal to the width of the picture). A tile scan may indicate a specific sequential ordering of CTUs partitioning a picture, wherein the CTUs may be sequentially aligned with a CTU raster scan within a tile, and tiles within a picture may be sequentially aligned with a raster scan of the tiles of the picture. (A tile scan is a specific sequential ordering of CTUs partitioning a picture in which the CTUs are ordered consecutively in CTU raster scan in a tile whereas tiles in a picture are ordered consecutively in a raster scan of the tiles of the picture). A slice includes an integer number of complete tiles or an integer number of consecutive lines in a tile of a picture or an integer number of complete tiles, which may be contained exclusively in a single NAL unit. complete CTU rows within a tile of a picture that may be exclusively contained in a single NAL unit)

Meanwhile, one picture may be divided into two or more subpictures. A subpicture may be a rectangular region of one or more slices within a picture.

A pixel or pel may mean a minimum unit constituting one picture (or image). Also, as a term corresponding to a pixel, a 'sample' may be used. The sample may generally represent a pixel or a value of a pixel, may represent only a pixel/pixel value of a luma component, or may represent only a pixel/pixel value of a chroma component.

A unit may represent a basic unit of image processing. The 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 (ex. cb, cr) blocks. A unit may be used interchangeably with terms such as a block or an area in some cases. In a general case, the MxN block may include samples (or sample arrays) or a set (or arrays) of transform coefficients including M columns and N rows.

In this document, "A or B (A or B)" may mean "only A", "only B", or "both A and B". In other words, “A or B (A or B)” in this document may be interpreted as “A and/or B (A and/or B)”. For example, in this document "A, B or C(A, B or C)" means "only A", "only B", "only C", or "any and any combination of A, B and C ( any combination of A, B and C)".

A slash (/) or a comma (comma) used in this document may mean “and/or”. For example, “A/B” may mean “A and/or B”. Accordingly, “A/B” may mean “only A”, “only B”, or “both A and B”. For example, “A, B, C” may mean “A, B, or C”.

In this document, “at least one of A and B” may mean “only A”, “only B” or “both A and B”. Also, in this document, the expression "at least one of A or B" or "at least one of A and/or B" means "at least one It can be interpreted the same as "A and B (at least one of A and B)".

Also, in this document "at least one of A, B and C" means "only A", "only B", "only C", or "A, B and C" any combination of A, B and C". Also, “at least one of A, B or C” or “at least one of A, B and/or C” means can mean "at least one of A, B and C".

Also, parentheses used in this document may mean “for example”. Specifically, when “prediction (intra prediction)” is indicated, “intra prediction” may be proposed as an example of “prediction”. In other words, “prediction” in this document is not limited to “intra prediction”, and “intra prediction” may be proposed as an example of “prediction”. Also, even when “prediction (ie, intra prediction)” is indicated, “intra prediction” may be proposed as an example of “prediction”.

Technical features that are individually described in one drawing in this document may be implemented individually or may be implemented at the same time.

2 is a diagram schematically illustrating a configuration of a video/image encoding apparatus to which embodiments of the present document may be applied. Hereinafter, the encoding device may include an image encoding device and/or a video encoding device.

2, the encoding apparatus 200 includes an image partitioner 210, a predictor 220, a residual processor 230, an entropy encoder 240, It may be configured to include an adder 250 , a filter 260 , and a memory 270 . The prediction unit 220 may include an inter prediction unit 221 and an intra prediction unit 222 . The residual processing unit 230 may include a transformer 232 , a quantizer 233 , an inverse quantizer 234 , and an inverse transformer 235 . The residual processing unit 230 may further include a subtractor 231 . The adder 250 may be referred to as a reconstructor or a reconstructed block generator. The above-described image segmentation unit 210, prediction unit 220, residual processing unit 230, entropy encoding unit 240, adder 250 and filtering unit 260 may include one or more hardware components ( For example, by an encoder chipset or processor). 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 a memory 270 as an internal/external component.

The image dividing unit 210 may divide an input image (or a picture, a frame) input to the encoding apparatus 200 into one or more processing units. For example, the processing unit may be referred to as a coding unit (CU). In this case, the coding unit is to be recursively divided according to a quad-tree binary-tree ternary-tree (QTBTTT) structure from a coding tree unit (CTU) or largest coding unit (LCU). can For example, one coding unit may be divided into a plurality of coding units having a lower depth based on a quad tree structure, a binary tree structure, and/or a ternary structure. In this case, for example, a quad tree structure may be applied first and a binary tree structure and/or a ternary structure may be applied later. Alternatively, the binary tree structure may be applied first. A coding procedure according to this document may be performed based on the final coding unit that is no longer divided. In this case, the maximum coding unit may be directly used as the final coding unit based on coding efficiency according to image characteristics, or the coding unit may be recursively divided into coding units having a lower depth than the optimal coding unit if necessary. A coding unit of the size of 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. 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 be divided or partitioned from the above-described final coding unit, respectively. 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 the transform coefficient.

A unit may be used interchangeably with terms such as a block or an area in some cases. In general, an MxN block may represent a set of samples or transform coefficients including M columns and N rows. A sample may generally represent a pixel or a value of a pixel, may represent only a pixel/pixel value of a luma component, or may represent only a pixel/pixel value of a chroma component. A sample may be used as a term corresponding to a picture (or image) as a pixel or a pel.

The encoding apparatus 200 subtracts the prediction signal (predicted block, prediction sample array) output from the inter prediction unit 221 or the intra prediction unit 222 from the input image signal (original block, original sample array) to obtain a residual A signal (residual signal, residual block, residual sample array) may be generated, and the generated residual signal is transmitted to the converter 232 . In this case, as illustrated, a unit for subtracting a prediction signal (prediction block, prediction sample array) from an input image signal (original block, original sample array) in the encoder 200 may be referred to as a subtraction unit 231 . The prediction unit may perform prediction on a processing target block (hereinafter, referred to as a current block) and generate a predicted block including prediction samples for the current block. The prediction unit may determine whether intra prediction or inter prediction is applied on a current block or CU basis. The prediction unit may generate various information related to prediction, such as prediction mode information, and transmit it to the entropy encoding unit 240 , as will be described later in the description of each prediction mode. The prediction information may be encoded by the entropy encoding unit 240 and output in the form of a bitstream.

The intra prediction unit 222 may predict the current block with reference to samples in the current picture. The referenced samples may be located in the neighborhood of the current block or may be located apart from each other according to the prediction mode. In intra prediction, prediction modes may include a plurality of non-directional modes and a plurality of directional modes. The non-directional mode may include, for example, a DC mode and a planar mode (Planar mode). The directional mode may include, for example, 33 directional prediction modes or 65 directional prediction modes according to the granularity of the prediction direction. However, this is an example, and a higher or lower number of directional prediction modes may be used according to a setting. The intra prediction unit 222 may determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring block.

The inter prediction unit 221 may derive the predicted block for the current block based on the reference block (reference sample array) specified by the motion vector on the reference picture. In this case, in order to reduce the amount of motion information transmitted in the inter prediction mode, motion information may be predicted in units of blocks, subblocks, or samples based on the correlation between motion information between neighboring blocks and the current block. The motion information may include a motion vector and a reference picture index. The motion information may further include inter prediction direction (L0 prediction, L1 prediction, Bi prediction, etc.) information. In the case of inter prediction, the neighboring blocks may include spatial neighboring blocks existing in the current picture and temporal neighboring blocks present 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 temporal neighboring block may be called a collocated reference block, a collocated CU (colCU), etc., and a reference picture including the temporally neighboring block may be called a collocated picture (colPic). may be For example, the inter prediction unit 221 constructs a motion information candidate list based on neighboring blocks, and provides information indicating which candidate is used to derive a motion vector and/or a reference picture index of the current block. can create Inter prediction may be performed based on various prediction modes. For example, in the skip mode and merge mode, the inter prediction unit 221 may use motion information of a neighboring block as motion information of the current block. In the skip mode, unlike the merge mode, a residual signal may not be transmitted. In the case of motion vector prediction (MVP) mode, the motion vector of the current block is determined by using a motion vector of a neighboring block as a motion vector predictor and signaling a motion vector difference. can direct

The prediction unit 220 may generate a prediction signal based on various prediction methods to be described later. For example, the prediction unit may apply intra prediction or inter prediction for prediction of one block, and may simultaneously apply intra prediction and inter prediction. This can be called combined inter and intra prediction (CIIP). In addition, the prediction unit may be based on an intra block copy (IBC) prediction mode or based on a palette mode for prediction of a block. The IBC prediction mode or the palette mode may be used for video/video coding of content such as games, for example, screen content coding (SCC). IBC basically performs prediction within the current picture, but may be performed similarly to inter prediction in that a reference block is derived within the current picture. That is, IBC may use at least one of the inter prediction techniques described in this document. The palette mode may be viewed as an example of intra coding or intra prediction. When the palette mode is applied, the sample value in the picture may be signaled based on information about the palette table and palette index.

The prediction signal generated by the prediction unit (including the inter prediction unit 221 and/or the intra prediction unit 222 ) may be used to generate a reconstructed signal or may be used to generate a residual signal. The transform unit 232 may generate transform coefficients by applying a transform technique to the residual signal. For example, the transformation technique may include at least one of Discrete Cosine Transform (DCT), Discrete Sine Transform (DST), Graph-Based Transform (GBT), or Conditionally Non-linear Transform (CNT). Here, GBT means a transformation obtained from this graph when expressing relationship information between pixels in a graph. CNT refers to a transformation obtained by generating a prediction signal using all previously reconstructed pixels and based thereon. Also, the transformation process may be applied to a block of pixels having the same size as a square, or may be applied to a block of a variable size that is not a square.

The quantization unit 233 quantizes the transform coefficients and transmits them to the entropy encoding unit 240, and the entropy encoding unit 240 encodes the quantized signal (information on the quantized transform coefficients) and outputs it as a bitstream. have. Information about the quantized transform coefficients may be referred to as residual information. The quantization unit 233 may rearrange the quantized transform coefficients in the block form into a one-dimensional vector form based on a coefficient scan order, and the quantized transform coefficients in the one-dimensional vector form are quantized based on the quantized transform coefficients in the one-dimensional vector form. Information about the transform coefficients may be generated. The entropy encoding unit 240 may perform various encoding methods such as, for example, exponential Golomb, context-adaptive variable length coding (CAVLC), and context-adaptive binary arithmetic coding (CABAC). The entropy encoding unit 240 may encode information necessary for video/image reconstruction (eg, values of syntax elements, etc.) other than the quantized transform coefficients together or separately. Encoded information (eg, encoded video/image information) may be transmitted or stored in a network abstraction layer (NAL) unit unit in the form of a bitstream. The video/image information may further include information about 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). Also, the video/image information may further include general constraint information. In this document, information and/or syntax elements transmitted/signaled from the encoding device to the decoding device may be included in 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 over a network or may be 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 USB, SD, CD, DVD, Blu-ray, HDD, and SSD. In the signal output from the entropy encoding unit 240, a transmitting unit (not shown) and/or a storing unit (not shown) for storing may be configured as internal/external elements of the encoding apparatus 200, or the transmitting unit It may be included in the entropy encoding unit 240 .

The quantized transform coefficients output from the quantization unit 233 may be used to generate a prediction signal. For example, the residual signal (residual block or residual samples) may be reconstructed by applying inverse quantization and inverse transform to the quantized transform coefficients through the inverse quantizer 234 and the inverse transform unit 235 . The adder 250 adds the reconstructed residual signal to the prediction signal output from the inter prediction unit 221 or the intra prediction unit 222 to obtain a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array). can be created When there is no residual for the block to be processed, such as when the skip mode is applied, the predicted block may be used as a reconstructed block. The adder 250 may be referred to as a restoration unit or a restoration block generator. The generated reconstructed signal may be used for intra prediction of the next processing object block in the current picture, or may be used for inter prediction of the next picture after filtering as described below.

Meanwhile, luma mapping with chroma scaling (LMCS) may be applied during picture encoding and/or restoration.

The filtering unit 260 may improve subjective/objective image quality by applying filtering to the reconstructed signal. For example, the filtering unit 260 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and convert the modified reconstructed picture to the memory 270 , specifically the DPB of the memory 270 . can be stored in The various filtering methods may include, for example, deblocking filtering, a sample adaptive offset, an adaptive loop filter, a bilateral filter, and the like. The filtering unit 260 may generate various types of filtering-related information and transmit it to the entropy encoding unit 240 , as will be described later in the description of each filtering method. The filtering-related information may be encoded by the entropy encoding unit 240 and output in the form of a bitstream.

The modified reconstructed picture transmitted to the memory 270 may be used as a reference picture in the inter prediction unit 221 . When inter prediction is applied through this, the encoding apparatus can avoid prediction mismatch between the encoding apparatus 200 and the decoding apparatus, and can also improve encoding efficiency.

The memory 270 DPB may store the corrected reconstructed picture to be used as a reference picture in the inter prediction unit 221 . The memory 270 may store motion information of a block in which motion information in the current picture is derived (or encoded) and/or motion information of blocks in an already reconstructed picture. The stored motion information may be transmitted 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 may store reconstructed samples of blocks reconstructed in the current picture, and may transmit the reconstructed samples to the intra prediction unit 222 .

3 is a diagram schematically illustrating a configuration of a video/image decoding apparatus to which embodiments of the present document may be applied. Hereinafter, the decoding device may include an image decoding device and/or a video decoding device.

Referring to FIG. 3 , the decoding apparatus 300 includes an entropy decoder 310 , a residual processor 320 , a predictor 330 , an adder 340 , and a filtering unit. (filter, 350) and may be configured to include a memory (memoery, 360). The prediction unit 330 may include an inter prediction unit 331 and an intra prediction unit 332 . The residual processor 320 may include a dequantizer 321 and an inverse transformer 321 . The entropy decoding unit 310 , the residual processing unit 320 , the prediction unit 330 , the addition unit 340 , and the filtering unit 350 are one hardware component (eg, a decoder chipset or a processor according to an embodiment). ) can be configured by 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 a memory 360 as an internal/external component.

When a bitstream including video/image information is input, the decoding apparatus 300 may reconstruct an image corresponding to a process in which the video/image information is processed in the encoding apparatus of FIG. 2 . For example, the decoding apparatus 300 may derive units/blocks based on block division related information obtained from the bitstream. The decoding apparatus 300 may perform decoding by using a processing unit applied in the encoding apparatus. Thus, the processing unit of decoding may be, for example, a coding unit, and the coding unit may be divided according to a quad tree structure, a binary tree structure and/or a ternary tree structure from a coding tree unit or a largest coding unit. One or more transform units may be derived from a coding unit. In addition, the reconstructed image signal decoded and output through the decoding apparatus 300 may be reproduced through the reproducing apparatus.

The decoding apparatus 300 may receive a signal output from the encoding apparatus of FIG. 2 in the form of a bitstream, and the received signal may be decoded through the entropy decoding unit 310 . For example, the entropy decoding unit 310 may parse the bitstream to derive information (eg, video/image information) required for image restoration (or picture restoration). The video/image information may further include information about 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). Also, the video/image information may further include general constraint information. The decoding apparatus may decode the picture further based on the information on the parameter set and/or the general restriction information. Signaled/received information and/or syntax elements described later in this document may be decoded through the decoding procedure and obtained from the bitstream. For example, the entropy decoding unit 310 decodes information in a bitstream based on a coding method such as exponential Golomb encoding, CAVLC or CABAC, and a value of a syntax element required for image reconstruction and a quantized value of a transform coefficient related to a residual can be printed out. In more detail, the CABAC entropy decoding method receives a bin corresponding to each syntax element in a bitstream, and decodes the syntax element information to be decoded and the decoding information of the surrounding and decoding target blocks or the symbol/bin information decoded in the previous step. A context model is determined using the context model, and the probability of occurrence of a bin is predicted according to the determined context model, and a symbol corresponding to the value of each syntax element can be generated by performing arithmetic decoding of the bin. have. In this case, the CABAC entropy decoding method may update the context model by using the decoded symbol/bin information for the context model of the next symbol/bin after determining the context model. Prediction-related information among the information decoded by the entropy decoding unit 310 is provided to the prediction unit (the inter prediction unit 332 and the intra prediction unit 331), and the entropy decoding unit 310 performs entropy decoding. Dual values, that is, quantized transform coefficients and related parameter information may be input to the residual processing unit 320 . The residual processing unit 320 may derive a residual signal (residual block, residual samples, residual sample array). Also, information on filtering among the information decoded by the entropy decoding unit 310 may be provided to the filtering unit 350 . On the other hand, a receiving unit (not shown) that receives a signal output from the encoding device may be further configured as an internal/external element of the decoding device 300 , or the receiving unit may be a component of the entropy decoding unit 310 . On the other hand, the decoding apparatus according to this document may be called a video/image/picture decoding apparatus, and the decoding apparatus is divided into an information decoder (video/image/picture information decoder) and a sample decoder (video/image/picture sample decoder). may be The information decoder may include the entropy decoding unit 310 , and the sample decoder includes the inverse quantization unit 321 , the inverse transform unit 322 , the adder 340 , the filtering unit 350 , and the memory 360 . ), an inter prediction unit 332 , and an intra prediction unit 331 .

The inverse quantizer 321 may inverse quantize the quantized transform coefficients to output transform coefficients. The inverse quantizer 321 may rearrange the quantized transform coefficients in a two-dimensional block form. In this case, the rearrangement may be performed based on the coefficient scan order performed by the encoding device. The inverse quantizer 321 may perform inverse quantization on the quantized transform coefficients using a quantization parameter (eg, quantization step size information) and obtain transform coefficients.

The inverse transform unit 322 inverse transforms the transform coefficients to obtain a residual signal (residual block, residual sample array).

The prediction unit 330 may perform prediction on the current block and generate a predicted block including prediction samples for the current block. The prediction unit 330 may determine whether intra prediction or inter prediction is applied to the current block based on the prediction information output from the entropy decoding unit 310, and determine a specific intra/inter prediction mode. can

The prediction unit 330 may generate a prediction signal based on various prediction methods to be described later. For example, the prediction unit 330 may apply intra prediction or inter prediction for prediction of one block, and may simultaneously apply intra prediction and inter prediction. This can be called combined inter and intra prediction (CIIP). Also, the prediction unit 330 may be based on an intra block copy (IBC) prediction mode or based on a palette mode for prediction of a block. The IBC prediction mode or the palette mode may be used for video/video coding of content such as games, for example, screen content coding (SCC). IBC basically performs prediction within the current picture, but may be performed similarly to inter prediction in that a reference block is derived within the current picture. That is, IBC may use at least one of the inter prediction techniques described in this document. The palette mode may be viewed as an example of intra coding or intra prediction. When the palette mode is applied, information about the palette table and the palette index may be included in the video/image information and signaled.

The intra prediction unit 331 may predict the current block with reference to samples in the current picture. The referenced samples may be located in the neighborhood of the current block or may be located apart from each other according to the prediction mode. In intra prediction, prediction modes may include a plurality of non-directional modes and a plurality of directional modes. The intra prediction unit 331 may determine the prediction mode applied to the current block by using the prediction mode applied to the neighboring block.

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

The adder 340 restores the obtained residual signal by adding it to the prediction signal (predicted block, prediction sample array) output from the prediction unit (including the inter prediction unit 332 and/or the intra prediction unit 331 ). A signal (reconstructed picture, reconstructed block, reconstructed sample array) may be generated. When there is no residual for the block to be processed, such as when the skip mode is applied, the predicted block may be used as a reconstructed block.

The adder 340 may be referred to as a restoration unit or a restoration block generator. The generated reconstructed signal may be used for intra prediction of the next processing object block in the current picture, may be output through filtering as described below, or may be used for inter prediction of the next picture.

Meanwhile, luma mapping with chroma scaling (LMCS) may be applied in the picture decoding process.

The filtering unit 350 may improve subjective/objective image quality by applying filtering to the reconstructed signal. For example, the filtering unit 350 may generate a modified reconstructed picture by applying various filtering methods to the reconstructed picture, and store the modified reconstructed picture in the memory 360 , specifically, the DPB of the memory 360 . can be sent to The various filtering methods may include, for example, deblocking filtering, a sample adaptive offset, an adaptive loop filter, a bilateral filter, and the like.

The (modified) reconstructed picture stored in the DPB of the memory 360 may be used as a reference picture in the inter prediction unit 332 . The memory 360 may store motion information of a block from which motion information in the current picture is derived (or decoded) and/or motion information of blocks in an already reconstructed picture. The stored motion information may be transmitted 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 may store reconstructed samples of blocks reconstructed in the current picture, and may transmit the reconstructed samples to the intra prediction unit 331 .

In this document, the embodiments described in the filtering unit 260 , the inter prediction unit 221 , and the intra prediction unit 222 of the encoding apparatus 200 are the filtering unit 350 and the inter prediction unit of the decoding apparatus 300 , respectively. The same or corresponding application may be applied to the unit 332 and the intra prediction unit 331 .

As described above, prediction is performed to increase compression efficiency in video coding. Through this, it is possible to generate a predicted block including prediction samples for a current block that is a coding target block. Here, the predicted block includes prediction samples in a spatial domain (or pixel domain). The predicted block is derived equally from the encoding device and the decoding device, and the encoding device decodes information (residual information) about the residual between the original block and the predicted block, not the original sample value of the original block itself. By signaling to the device, image coding efficiency can be increased. The decoding apparatus may derive a residual block including residual samples based on the residual information, and generate a reconstructed block including reconstructed samples by summing the residual block and the predicted block, and reconstruct the reconstructed blocks. It is possible to generate a restored picture including

The residual information may be generated through transformation and quantization procedures. For example, the encoding apparatus derives a residual block between the original block and the predicted block, and performs a transform procedure on residual samples (residual sample array) included in the residual block to derive transform coefficients And, by performing a quantization procedure on the transform coefficients to derive quantized transform coefficients, the associated residual information may be signaled to the decoding apparatus (via a bitstream). Here, the residual information may include information such as value information of the quantized transform coefficients, location information, a transform technique, a transform kernel, and a quantization parameter. The decoding apparatus may perform an inverse quantization/inverse transformation procedure based on the residual information and derive residual samples (or residual blocks). The decoding apparatus may generate a reconstructed picture based on the predicted block and the residual block. The encoding apparatus may also inverse quantize/inverse transform the quantized transform coefficients for reference for inter prediction of a later picture to derive a residual block, and generate a reconstructed picture based thereon.

In this document, at least one of quantization/inverse quantization and/or transform/inverse transform may be omitted. When the quantization/inverse quantization is omitted, the quantized transform coefficient may be referred to as a transform coefficient. When the transform/inverse transform is omitted, the transform coefficient may be called a coefficient or a residual coefficient, or may still be called a transform coefficient for uniformity of expression.

Also, in this document, a quantized transform coefficient and a transform coefficient may be referred to as a transform coefficient and a scaled transform coefficient, respectively. In this case, the residual information may include information on transform coefficient(s), and the information on the transform coefficient(s) may be signaled through residual coding syntax. Transform coefficients may be derived based on the residual information (or information about the transform coefficient(s)), and scaled transform coefficients may be derived through inverse transform (scaling) on the transform coefficients. Residual samples may be derived based on an inverse transform (transform) of the scaled transform coefficients. This may be applied/expressed in other parts of this document as well.

4 exemplarily shows a hierarchical structure for a coded video/image.

Referring to FIG. 4 , the coded video/image is a video coding layer (VCL) that handles decoding processing of the video/image and itself, a subsystem that transmits and stores coded information, and the VCL and subsystem It exists between them and is divided into a network abstraction layer (NAL) that is responsible for network adaptation functions.

In VCL, VCL data including compressed video data (slice data) is generated, or picture parameter set (PPS), sequence parameter set (SPS), video parameter set (Video Parameter Set: A supplemental enhancement information (SEI) message additionally necessary for a parameter set including information such as VPS) or an image decoding process may be generated.

In the NAL, a NAL unit may be generated by adding header information (NAL unit header) to a raw byte sequence payload (RBSP) generated in the VCL. In this case, the RBSP refers to slice data, parameter sets, SEI messages, etc. generated in the VCL. The NAL unit header may include NAL unit type information specified according to RBSP data included in the corresponding NAL unit.

As shown in FIG. 4 , the NAL unit may be divided into a VCL NAL unit and a Non-VCL NAL unit according to the RBSP generated in the VCL. A VCL NAL unit may mean a NAL unit including information (slice data) about an image, and the Non-VCL NAL unit is a NAL unit containing information (parameter set or SEI message) necessary for decoding an image. can mean

The above-described VCL NAL unit and Non-VCL NAL unit may be transmitted through a network by attaching header information according to a data standard of a subsystem. For example, the NAL unit may be transformed into a data form of a predetermined standard such as H.266/VVC file format, Real-time Transport Protocol (RTP), Transport Stream (TS), and transmitted through various networks.

As described above, in the NAL unit, the NAL unit type may be specified according to the RBSP data structure included in the corresponding NAL unit, and information on the NAL unit type may be stored and signaled in the NAL unit header.

For example, the NAL unit may be largely classified into a VCL NAL unit type and a Non-VCL NAL unit type according to whether or not the NAL unit includes image information (slice data). The VCL NAL unit type may be classified according to properties and types of pictures included in the VCL NAL unit, and the Non-VCL NAL unit type may be classified according to the type of a parameter set.

The following is an example of the NAL unit type specified according to the type of parameter set included in the Non-VCL NAL unit type.

- APS (Adaptation Parameter Set) NAL unit: Type for NAL unit including APS

- DPS (Decoding Parameter Set) NAL unit: a type for a NAL unit including a DPS

- VPS (Video Parameter Set) NAL unit: Type of NAL unit including VPS

- SPS (Sequence Parameter Set) NAL unit: Type for NAL unit including SPS

- PPS (Picture Parameter Set) NAL unit: Type of NAL unit including PPS

- PH (Picture header) NAL unit: Type of NAL unit including PH

The above-described NAL unit types have syntax information for the NAL unit type, and the syntax information may be stored and signaled in a NAL unit header. For example, the syntax information may be nal_unit_type, and NAL unit types may be specified by a nal_unit_type value.

Meanwhile, as described above, one picture may include a plurality of slices, and one slice may include a slice header and slice data. In this case, one picture header may be further added to a plurality of slices (a slice header and a slice data set) in one picture. The picture header (picture header syntax) may include information/parameters commonly applicable to the picture. For example, a picture may consist of slices of different types, such as intra-coded slices (ie, I-slice) and/or inter-coded slices (ie, P-slice and B-slice). . In this case, the picture header may include information/parameters applied to the intra-coded slice and the inter-coded slice. Alternatively, one picture may consist of one type of slices.

The slice header (slice header syntax) may include information/parameters commonly applicable to the slice. The APS (APS syntax) or PPS (PPS syntax) may include information/parameters commonly applicable to one or more slices or pictures. The SPS (SPS syntax) may include information/parameters commonly applicable to one or more sequences. The VPS (VPS syntax) may include information/parameters commonly applicable to multiple layers. The DPS (DPS syntax) may include information/parameters commonly applicable to the entire video. The DPS may include information/parameters related to concatenation of a coded video sequence (CVS). In this document, high level syntax (HLS) may include at least one of the APS syntax, PPS syntax, SPS syntax, VPS syntax, DPS syntax, picture header syntax, and slice header syntax.

In this document, the video/image information encoded from the encoding device to the decoding device and signaled in the form of a bitstream includes, as well as intra-picture partitioning-related information, intra/inter prediction information, residual information, in-loop filtering information, etc. Information included in the slice header, information included in the picture header, information included in the APS, information included in the PPS, information included in the SPS, information included in the VPS, and/or information included in the DPS can do. In addition, the video/image information may further include information of a NAL unit header.

Meanwhile, the encoding apparatus and the decoding apparatus may encode/decode the picture by dividing the picture into predetermined units. For example, the encoding apparatus and the decoding apparatus may encode/decode the picture by dividing the picture into sub-pictures, slices, and/or tiles.

As described above, one picture may be divided into one or more tile rows and/or one or more tile columns. A tile is a specific tile column in a picture and a rectangular area of CTUs within a specific tile column. CTUs included in one tile may be arranged according to a specific scan order. For example, CTUs included in one tile may be sequentially arranged according to a raster scan order within the tile. A slice may consist of an integer number of complete tiles, or an integer number of consecutive CTU rows contained within a tile of a picture.

In this case, the vertical boundary of each slice in the picture may be the vertical boundary of the tile. A horizontal boundary of each slice within a picture may be a horizontal boundary of a tile or a horizontal boundary of a CTU within a tile. When the horizontal boundary of each slice in the picture is not the horizontal boundary of the tile but the horizontal boundary of the CTU within the tile, the tile in the picture may be divided into a plurality of rectangular slices, and each of the plurality of rectangular slices is an integer number It may consist of consecutive CTU rows.

Slices may exist in raster scan slice mode and rectangular slice mode. For the raster scan slice mode, one slice may include one or more tiles arranged in a raster scan within a picture. For rectangular slice mode, one slice may contain an integer number of complete tiles forming a rectangular area within a picture or may contain an integer number of consecutive CTU rows within one tile forming a rectangular area within a picture. Tiles in a rectangular slice may be scanned according to a raster scan order within an area of the rectangular slice.

One sub-picture may include one or more slices constituting a rectangular region of the picture. A boundary of each subpicture may always be a slice boundary, and a vertical boundary of each subpicture may always be a vertical boundary of a tile.

In addition, at least one of the following conditions must be satisfied for each subpicture and tile.

- All CTUs in a subpicture belong to the same tile.

-All CTUs in a tile belong to the same subpicture.

In this regard, when one picture is divided into multiple subpictures, multiple tiles and multiple slices, information related to a subpicture may be signaled through the SPS, and information related to a tile and a rectangular slice is It may be signaled through the PPS, and information related to a raster scan slice may be signaled through a slice header.

5 shows an embodiment in which a picture is divided into slices and tiles.

Here, a thick line indicates a boundary of a slice, a thin line indicates a boundary of a tile, and a dotted line indicates a boundary of a CTU. Referring to FIG. 5 , a picture is composed of 216 (18 x 12) CTUs, 3 tile columns, and 4 tile rows. Accordingly, the picture is composed of 12 tiles and 3 slices according to the raster scan slice mode. Here, among the three slices, slice 1 according to the raster scan order is composed of two complete tiles according to the raster scan order, and slice 2 is composed of 5 complete tiles according to the raster scan order, 3 A burn slice consists of 5 complete tiles according to the raster scan order. A vertical boundary of each of the three slices is constituted by a vertical boundary of a tile in the picture. A horizontal boundary of each of the three slices is composed of a horizontal boundary of a tile (in-tile CTU) in the picture.

6 illustrates an embodiment in which a picture is divided into slices and tiles.

Similarly, the thick line indicates the boundary of the slice, the thin line indicates the boundary of the tile, and the dotted line indicates the boundary of the CTU. Referring to FIG. 6 , a picture consists of 216 (18 x 12) CTUs, 6 tile columns, and 4 tile rows. Accordingly, the picture consists of 24 tiles and 9 slices according to the rectangular slice mode. Here, each of slices 1, 2, 3, 7, 8, and 9 according to the raster scan order among the 9 slices is composed of two complete tiles, and each of slices 4, 5 and 6 is 4 It consists of complete tiles. A vertical boundary of each of the nine slices is constituted by a vertical boundary of a tile in the picture. A horizontal boundary of each of the nine slices is composed of a horizontal boundary of a tile (in-tile CTU) in the picture.

7 illustrates an embodiment in which a picture is divided into slices and tiles.

Similarly, the thick line indicates the boundary of the slice, the thin line indicates the boundary of the tile, and the dotted line indicates the boundary of the CTU. Referring to FIG. 7 , a picture consists of 216 (18 x 12) CTUs, three tile columns, and two tile rows. Accordingly, the picture is composed of 6 tiles and 7 slices according to the rectangular slice mode. Here, slice 1 according to the raster scan order among the 7 slices is composed of two complete tiles, and slices 2, 3, 4, and 5 are each composed of 3 consecutive CTU rows included in the tile. and each of slices 6 and 7 consists of one complete tile. A vertical boundary of each of the seven slices is constituted by a vertical boundary of a tile in the picture. A horizontal boundary of each of slices 1, 6, and 7 among the 7 slices is configured as a horizontal boundary of a tile (in-tile CTU) in the picture. The upper horizontal boundary of each of slices 2 and 3 among the 7 slices is constituted by a horizontal boundary of a tile (in-tile CTU) in the picture, and a lower horizontal boundary is a horizontal boundary of CTUs in the tile, which is not a horizontal boundary of the tile is composed of The upper horizontal boundary of each of slices 4 and 5 among the 7 slices is not the horizontal boundary of the tile, but the horizontal boundary of CTUs in the tile, and the lower horizontal boundary is the horizontal boundary of the tile (CTU in the tile) in the picture is composed of

8 shows an embodiment in which a picture is divided into slices and tiles.

Similarly, the thick line indicates the boundary of the slice, the thin line indicates the boundary of the tile, and the dotted line indicates the boundary of the CTU. Referring to FIG. 8 , a picture consists of 216 (18 x 12) CTUs, two tile columns, and two tile rows. Accordingly, the picture is composed of 4 tiles and 5 slices according to the rectangular slice mode. Here, among the five slices, each of slices 1, 4, and 5 according to the raster scan order consists of one complete tile, and the second slice consists of two consecutive CTU rows included in the tile, 3 A burn slice consists of 4 consecutive CTU rows included in a tile. A horizontal boundary of each of slices 1, 4, and 5 among the five slices is configured as a horizontal boundary of a tile (in-tile CTU) in the picture. The upper horizontal boundary of the second slice among the five slices is composed of the horizontal boundary of the tile (in-tile CTU) in the picture, and the lower horizontal boundary is not the horizontal boundary of the tile, but the horizontal boundary of the CTUs in the tile. The upper horizontal boundary of the third slice among the five slices is not the horizontal boundary of the tile, but the horizontal boundary of CTUs in the tile, and the lower horizontal boundary is the horizontal boundary of the tile (CTU in the tile) in the picture.

9 shows an embodiment in which a picture is divided into slices (sub pictures) and tiles.

Here, a thick dotted line indicates a boundary of a slice or a subpicture, a solid line indicates a boundary of a tile, and a thin dotted line indicates a boundary of a CTU. In addition, each slice of FIG. 9 represents one subpicture. Referring to FIG. 9 , a picture consists of 240 (20 x 12) CTUs, 6 tile columns, and 3 tile rows. Accordingly, the picture consists of 18 tiles and 24 slices (sub pictures). Here, each of slices 1 to 4, 9 to 12, and 17 to 20 slices (subpictures) according to the raster scan order among the 24 slices (subpictures) consists of one complete tile, and 5 to 8 , 13 to 16 and 21 to 24 slices (sub pictures) are composed of two consecutive CTU rows included in a tile. The horizontal boundary of each of slices 1 to 4, 9 to 12 and 17 to 20 (sub pictures) of the 24 slices (sub pictures) is the horizontal boundary of the tile (in-tile CTU) in the picture. . The upper horizontal boundary of slices 5, 6, 13, 14, 21 and 22 of the 24 slices (sub pictures) (sub pictures) is the horizontal boundary of the tile (in-tile CTU) in the picture, and , the lower horizontal boundary is composed of the horizontal boundary of CTUs in the tile, not the horizontal boundary of the tile. The upper horizontal boundary of slices 7, 8, 15, 16, 23, and 24 of the 24 slices (subpictures) (subpictures) is not the horizontal boundary of the tile, but the horizontal boundary of CTUs in the tile, and , the lower horizontal boundary is composed of a horizontal boundary of a tile (in-tile CTU) in the picture.

In relation to this, in order to signal information related to a rectangular slice, information related to the size of the rectangular slice in units of tiles and the position of the upper left tile of the next rectangular slice is signaled in the prior art. However, since information related to the size of the rectangular slice in units of tiles and the position of the upper left tile of the next rectangular slice is information that can be inferred without signaling/parsing, it is not necessary to separately signal.

Specifically, when a picture is composed of a plurality of rectangular slices, each of the plurality of rectangular slices may have the following characteristics that enable more efficient signaling.

- The first rectangular slice of the plurality of rectangular slices is always in the upper left corner of the picture.

- The picture is divided into the plurality of rectangular slices without gaps and overlaps.

- A left boundary and an upper boundary of each of the plurality of rectangular slices are composed of a boundary of the picture or a boundary of already decoded rectangular slices.

Considering the above characteristics, there is no need to explicitly signal/parse information such as the upper-left tile position for each rectangular slice and the size of each rectangular slice in order to obtain information related to the rectangular slice.

Similarly, in order to signal information related to a subpicture, information related to the size of the subpicture in units of CTU and the position of the upper left CTU of the next subpicture is signaled in the prior art. However, since information related to the size of the subpicture in units of CTU and the position of the upper left CTU of the next subpicture is information that can be inferred without signaling/parsing, there is no need for separate signaling.

Specifically, when a picture is composed of a plurality of sub-pictures, each of the plurality of sub-pictures may have the following characteristics that enable more efficient signaling.

- The first sub picture among the plurality of sub pictures is always in the upper left corner of the picture.

- The picture is divided into the plurality of sub pictures without gaps and overlaps.

- A left boundary and an upper boundary of each of the plurality of sub-pictures are composed of a boundary of the picture or a boundary of previously decoded sub-pictures.

Considering the above characteristics, in order to obtain information related to a subpicture, it is not necessary to explicitly signal/parse information such as the upper left CTU position for each subpicture and the size of each subpicture.

In addition, the existing signaling method is not an optimal method when a picture is divided into a plurality of tiles and each tile is included in one slice corresponding to one NAL unit, or when each slice includes at most one tile. can

In this regard, embodiments of the present document may include one or more of the following features.

1) In order to derive information on the layout (position, shape, size) of the rectangular slice, information on the lower right block (tile, CTU) of each rectangular slice may be signaled. For example, information on the lower right tile of a rectangular slice may be expressed in the form of a slice_bottom_right_tile_idx syntax element. Here, information on the lower right block of the last rectangular slice does not need to be signaled, and may be inferred as information (tile index) about the last tile in the picture. Through this, information on the upper left tile of each rectangular slice and information on the size (width, height) of each rectangular slice may be derived.

2) The upper-left block (ie, topLeftX, topLeftY), width (ie, sliceWidth), and height (ie, sliceHeight) for each slice can be derived as follows.

a) The x-coordinate of the first slice is 0, and the y-coordinate is 0.

b) A slice map of a two-dimensional array may be expressed as tileToSliceMap[m][n], where m may range from 0 to the number of block rows (tile rows) -1, and n is 0 to block columns ( The number of tile columns) may range from -1. The value of tileToSliceMap[m][n] can be initialized to a predetermined number (-1) not to be used.

c) bottomRightX is the x-coordinate of the lower-right block of each slice, bottomRightY is the y-coordinate of the lower-right block of each slice, topLeftX is the same as the x-coordinate of the lower-right block of each slice, and the width of each slice is 0 can be set. On the condition that j is less than 0 or the value of tileToSliceMap[bottomRightY][j] is not equal to -1, we can start a loop until j has the same value as bottomRightX, and decrement j with each pass. If j is not less than 0 and the value of tileToSliceMap[bottomRightY][j] is -1, in each pass the width of the slice is increased by 1, topLeftX is set to j, and the value of tileToSliceMap[bottomRightY][j] can be set as the index of the slice. At the end of the loop, topLeftX and the width of the slice can be derived.

d) topLeftY is the same as the y-coordinate of the lower-right block of each slice, and the height of each slice may be set to 1. On the condition that j is less than 0 or the value of tileToSliceMap[j][bottomRightX] is not equal to -1, we can start a loop until j has a value equal to bottomRightY, and decrement j with each pass. If j is not less than 0 and the value of tileToSliceMap[j][bottomRightX] is -1, the height of the slice is increased by 1 in each pass, topLeftY is set to j, and the value of tileToSliceMap[j][bottomRightX] can be set as the index of the slice. At the end of the loop, topLeftY and the height of the slice can be derived.

3) In order to signal the lower-right block information (slice_bottom_right_tile_idx syntax element) of the slice, a delta value between the lower-right block index and the previous slice may be signaled. That is, the slice_bottom_right_tile_idx syntax element may be replaced with the slice_bottom_right_delta_tile_idx syntax element, and the SliceBottomRightTileIdx[i] list may be derived as follows. For example, SliceBottomRightTileIdx[0] can be equal to slice_bottom_right_delta_tile_idx[0], SliceBottomRightTileIdx[1] can be equal to SliceBottomRightTileIdx[0] + 　slice_bottom_right_delta_tile_idx[1], and SliceBottomRightTile_idx[1] equal to SliceBottomRightTile_idx[1]. It may be the same as +　slice_bottom_right_delta_tile_idx[i].

4) When signaling the slice_bottom_right_delta_tile_idx syntax element, for example, the value of the slice_bottom_right_delta_tile_idx syntax element may always be an absolute value (a value greater than 0). The absolute value of the slice_bottom_right_delta_tile_idx syntax element may be signaled in the form of a slice_bottom_right_abs_delta_tile_idx syntax element. In this case, the sign value of the slice_bottom_right_delta_tile_idx syntax element may be separately signaled using the slice_bottom_right_tile_delta_sign_flag syntax element. As another example, the value of the slice_bottom_right_delta_tile_idx syntax element may be allowed to have both a positive value and a negative value (signaled by the se(v) function).

5) The slice_bottom_right_delta_tile_idx syntax element may be restricted not to have a value of 0 by signaling as a syntax element using the term “minus1”.

6) To improve signaling efficiency, the slice_bottom_right_delta_tile_idx syntax element may be signaled using a fixed length code (u(v) function). In this case, the fixed length code for the slice_bottom_right_delta_tile_idx syntax element is the number of bits allocated for signaling of the slice_bottom_right_delta_tile_idx syntax element, and may be signaled in advance.

7) In order to derive information on the layout (position, shape, size) of the subpicture, information on the lower right block (tile, CTU) of each subpicture may be signaled. For example, information on the lower right CTU of the subpicture may be expressed in the form of a subpic_ctu_bottom_right_idx syntax element. Here, information on the lower right block of the last sub-picture does not need to be signaled, and may be inferred as information (CTU index) on the last CTU in the picture. Through this, information on the upper left CTU of each subpicture and information on the size (width, height) of each subpicture can be derived.

8) The upper-left block (ie, topLeftX, topLeftY), width (ie, subpicWidth), and height (ie, subpicHeight) for each subpicture may be derived as follows.

a) The x-coordinate of the first subpicture is 0, and the y-coordinate is 0.

b) The subpicture map of the two-dimensional array may be expressed as ctuToSubpicMap[m][n], m may have a range from 0 to the number of block rows (CTU rows)-1, n is 0 to block columns The number of (CTU columns) may range from -1. The value of ctuToSubpicMap[m][n] can be initialized to a predetermined number (-1) so that it is not used.

c) bottomRightX is the x-coordinate of the lower-right block of each subpicture, bottomRightY is the y-coordinate of the lower-right block of each subpicture, and topLeftX is the same as the x-coordinate of the lower-right block of each subpicture, and the width of each subpicture can be set to 0. On the condition that j is less than 0 or the value of ctuToSubpicMap[bottomRightY][j] is not equal to -1, we can start a loop until j has the same value as bottomRightX, and decrement j with each pass. If j is not less than 0 and the value of ctuToSubpicMap[bottomRightY][j] is -1, the width of the subpicture is increased by 1 in each pass, topLeftX is set to j, and the value of ctuToSubpicMap[bottomRightY][j] is A value can be set as an index of a subpicture. When the loop ends, topLeftX and the width of the subpicture can be derived.

d) topLeftY is the same as the y-coordinate of the lower-right block of each sub-picture, and the height of each sub-picture may be set to 1. On the condition that j is less than 0 or the value of ctuToSubpicMap[j][bottomRightX] is not equal to -1, we can start a loop until j has the same value as bottomRightY, and decrement j with each pass. If j is not less than 0 and the value of ctuToSubpicMap[j][bottomRightX] is -1, the height of the subpicture is increased by 1 in each pass, topLeftY is set to j, and the value of ctuToSubpicMap[j][bottomRightX] is A value can be set as an index of a subpicture. When the loop ends, topLeftY and the height of the subpicture may be derived.

9) In order to signal the lower right block information (subpic_ctu_bottom_right_idx syntax element) of the sub picture, a delta value between the previous sub picture and the lower right block index may be signaled. That is, the subpic_ctu_bottom_right_idx syntax element may be replaced with the subpic_ctu_delta_bottom_right_idx syntax element, and the SubpicBottomRightCTUIdx[i] list may be derived as follows. For example, SubpicBottomRightCTUIdx[0] could be equal to subpic_ctu_delta_bottom_right_idx[0], SubpicBottomRightCTUIdx[1] could be equal to SubpicBottomRightCTUIdx[0]+　+　subpicBottom_ctu_delta_bottom_right_idx[Ri], SubpicBottom_ctu_delta_bottom_right_idx[Ri] could be equal to SubpicBottom_ctu_delta_bottom_right_idx[1] It may be the same as +　subpic_ctu_delta_bottom_right_idx[i].

10) When signaling the subpic_ctu_delta_bottom_right_idx syntax element, for example, the value of the subpic_ctu_delta_bottom_right_idx syntax element may always be an absolute value (a value greater than 0). The absolute value of the subpic_ctu_delta_bottom_right_idx syntax element may be signaled in the form of a subpic_ctu_abs_delta_bottom_right_idx syntax element. In this case, the sign value of the subpic_ctu_delta_bottom_right_idx syntax element may be separately signaled using the subpic_ctu_delta_bottom_right_sign_flag syntax element. As another example, the value of the subpic_ctu_delta_bottom_right_idx syntax element may be allowed to have both a positive value and a negative value (signaled with a se(v) function).

11) The subpic_ctu_delta_bottom_right_idx syntax element may be restricted not to have a value of 0 by signaling as a syntax element using the term “minus1”.

12) In order to improve signaling efficiency, the subpic_ctu_delta_bottom_right_idx syntax element may be signaled using a fixed length code (u(v) function). In this case, the fixed length code for the subpic_ctu_delta_bottom_right_idx syntax element is the number of bits allocated for signaling of the subpic_ctu_delta_bottom_right_idx syntax element, and may be signaled in advance.

13) A flag for designating whether each slice in a picture referring to the PPS includes one tile or a part of a tile may exist. For example, this flag may be expressed in the form of a max_one_tile_per_slice_flag syntax element. For example, when the max_one_tile_per_slice_flag syntax element has a value of 1, all slices in the picture referring to the PPS may be rectangular slices.

14) When the value of the max_one_tile_per_slice_flag syntax element is 1, the following characteristics may be applied.

a) The number of slices in the picture may be derived as the number of tiles in the picture plus the signaled number of slices. The signaled number of slices may be expressed in the form of a num_slices_signalled syntax element.

b) Signaling of the tile_idx_delta_present_flag syntax element may not exist, and the value of the tile_idx_delta_present_flag syntax element may be derived as 0.

c) Signaling of a slice width per tile may not exist. The slice width per tile may be derived as 1 (tile).

d) Signaling of slice height per tile may not exist. The slice height per tile may be derived as 1 (tile).

According to an embodiment proposed in this document, the image information may include sub-picture related information related to a sub picture existing in the picture. In this case, the sub-picture related information may be signaled as follows.

First, the subpicture related information may include a subpicture presence flag. For example, the subpicture presence flag may be related to whether information related to the subpicture is signaled. That is, the subpicture presence flag may indicate/indicate whether information related to the subpicture is signaled.

For example, the subpicture presence flag may be expressed in the form of a subpics_present_flag syntax element. For example, the subpics_present_flag syntax element may specify whether information related to a subpicture is signaled.

The subpicture related information may include information on the number of subpictures. For example, the information on the number of sub-pictures may be related to the number of sub-pictures in a picture. That is, the information on the number of sub-pictures may indicate/represent the number of sub-pictures in a picture.

For example, the information on the number of subpictures may be expressed in the form of a sps_num_subpics_minus1 syntax element. For example, the value +1 of the sps_num_subpics_minus1 syntax element may specify the number of sub pictures in a picture.

The subpicture related information may include CTU delta length information and CTU delta absolute value information. For example, the CTU delta length information may be related to the number of bits of the CTU delta absolute value information. That is, the CTU delta length information may indicate/represent the number of bits of the CTU delta absolute value information. For example, the value plus 1 of the CTU delta length information may be equal to the number of bits of the CTU delta absolute value information.

For example, the CTU delta length information may be represented in the form of a sps_subpic_ctu_bottom_right_delta_len_minus1 syntax element. For example, the value +1 of the sps_subpic_ctu_bottom_right_delta_len_minus1 syntax element may specify the number of bits of the CTU delta absolute value information.

The CTU delta absolute value information may be related to the lower right CTU index of the subpicture. For example, the CTU delta absolute value information may be related to the absolute value of the difference between the lower right CTU indices of the two subpictures. That is, the CTU delta absolute value information may indicate/represent the absolute value of the difference between the lower right CTU indices of the two subpictures.

For example, the CTU delta absolute value information may be represented in the form of a subpic_ctu_abs_delta_bottom_right_idx syntax element. For example, the subpic_ctu_abs_delta_bottom_right_idx syntax element may specify an absolute value of a difference value between lower-right CTU indices of two sub-pictures.

The subpicture related information may include a CTU delta code flag. For example, the CTU delta code flag may be related to the lower right CTU index of the subpicture. For example, the CTU delta code flag may be related to a sign of a difference value between lower right CTU indices of two subpictures. That is, the CTU delta code flag may indicate/indicate a sign of a difference value between the lower right CTU indexes of two subpictures.

For example, the CTU delta sign flag may be represented in the form of a subpic_ctu_delta_bottom_right_sign_flag syntax element. For example, the subpic_ctu_delta_bottom_right_sign_flag syntax element may specify a sign of a difference value between lower-right CTU indices of two sub-pictures.

At this time, for example, when the value of the CTU delta code flag is 1, the difference value between the lower right CTU indices of the two subpictures may have a positive value, and when the value of the CTU delta code flag is 0 , a difference value between the lower right CTU indices of the two subpictures may have a negative value.

The sub-picture related information may include a picture handling flag. For example, the picture handling flag may be related to whether a subpicture is treated as a picture in a decoding operation excluding the in-loop filtering operation. That is, the picture handling flag may indicate/indicate whether a subpicture is treated as a picture in a decoding operation excluding the in-loop filtering operation.

For example, the picture handling flag may be expressed in the form of a subpic_treated_as_pic_flag syntax element. For example, the subpic_treated_as_pic_flag syntax element may specify whether a subpicture is treated as a picture in a decoding operation excluding the in-loop filtering operation.

The subpicture related information may include a loop filter subpicture availability flag. For example, the loop filter subpicture availability flag may be related to whether an in-loop filtering operation is available at a boundary of a subpicture. That is, the loop filter subpicture availability flag may indicate/indicate whether the in-loop filtering operation is available at the boundary of the subpicture.

For example, the loop filter subpicture enable flag may be expressed in the form of a loop_filter_across_subpic_enabled_flag syntax element. For example, the loop_filter_across_subpic_enabled_flag syntax element may specify whether an in-loop filtering operation is available at the boundary of a subpicture.

For example, according to the embodiment, a sequence parameter set (SPS) may include the syntax shown in Table 1 below. The syntax of Table 1 below may be a part of the SPS.

Here, the semantics of the syntax elements included in the syntax of Table 1 may be expressed, for example, as shown in Table 2 below.

That is, the subpics_present_flag syntax element may indicate whether information related to a subpicture is signaled based on whether its value is 0 or 1. The subpics_present_flag syntax element may be referred to as the subpicture presence flag, and may be signaled through the SPS.

A value of +1 of the sps_num_subpics_minus1 syntax element may indicate the number of sub-pictures in a picture. The sps_num_subpics_minus1 syntax element may be referred to as the subpicture number information and may be signaled through the SPS.

The value +1 of the sps_subpic_ctu_bottom_right_delta_len_minus1 syntax element may indicate the number of bits of the CTU delta absolute value information (subpic_ctu_abs_delta_bottom_right_idx syntax element). The sps_subpic_ctu_bottom_right_delta_len_minus1 syntax element may be referred to as the CTU delta length information and may be signaled through the SPS.

The subpic_ctu_abs_delta_bottom_right_idx syntax element may indicate an absolute value of a difference value between lower-right CTU indices of two sub-pictures. The subpic_ctu_abs_delta_bottom_right_idx syntax element may be referred to as the CTU delta absolute value information and may be signaled through the SPS.

The subpic_ctu_delta_bottom_right_sign_flag syntax element may indicate a sign of a difference value between lower-right CTU indices of pictures based on whether the value is 0 or 1. The subpic_ctu_delta_bottom_right_sign_flag syntax element may be referred to as the CTU delta sign flag and may be signaled through the SPS.

The subpic_treated_as_pic_flag syntax element may indicate whether a subpicture is treated as a picture in a decoding operation excluding the in-loop filtering operation based on whether the value is 0 or 1. The subpic_treated_as_pic_flag syntax element may be called the picture handling flag and may be signaled through the SPS.

The loop_filter_across_subpic_enabled_flag syntax element may indicate whether an in-loop filtering operation is available at the boundary of a subpicture based on whether the value is 0 or 1. The loop_filter_across_subpic_enabled_flag syntax element may be referred to as the loop filter subpicture enable flag, and may be signaled through the SPS.

According to the embodiment, when the value of the subpicture presence flag is 1, the subpicture number information, the CTU delta length information, the CTU delta absolute value information, the CTU delta code flag, the picture handling flag, and the The loop filter subpicture availability flag may be configured/included in the SPS and signaled. On the other hand, when the value of the subpicture presence flag is not 1, the subpicture number information, the CTU delta length information, the CTU delta absolute value information, the CTU delta code flag, the picture handling flag, and the loop filter subpicture The available flag may not exist in the SPS.

In this case, for example, the CTU delta absolute value information and the CTU delta code flag may exist for each subpicture based on the subpicture number information.

In this way, when the value of the subpicture presence flag is 1, at least one sub picture existing in the current picture based on the subpicture number information, the CTU delta length information, the CTU delta absolute value information, and the CTU delta code flag. A picture can be derived.

According to an existing embodiment, when the value of the subpicture presence flag is 1, after signaling the subpicture number information, the upper left CTU x coordinate information (subpic_ctu_top_left_x) for each subpicture based on the subpicture number information syntax element), upper left CTU y coordinate information (subpic_ctu_top_left_y syntax element), width information (subpic_width_minus1 syntax element), and height information (subpic_height_minus1 syntax element) were signaled.

In contrast, according to the embodiment proposed in this document, when the value of the subpicture presence flag is 1, after signaling the subpicture number information, based on the subpicture number information, The CTU delta length information, the CTU delta absolute value information, and the CTU delta code flag may be signaled.

That is, according to the embodiment, in order to signal information related to the layout of each subpicture existing in the picture, upper left CTU x coordinate information, upper left CTU y coordinate information, width information and height information for each sub picture Instead, the CTU delta length information, the CTU delta absolute value information, and the CTU delta code flag may be signaled.

In the case of the above embodiment, compared to the existing embodiment, since a smaller number of bits can be allocated to signal information related to the layout of each subpicture present in the picture, the effect of increasing overall coding efficiency through this can represent

According to another embodiment proposed in this document, the image information may further include rectangular slice related information related to a rectangular slice existing in a picture. In this case, the rectangular slice related information may be signaled as follows.

First, the rectangular slice related information may include a no-picture partition flag. For example, the no-picture partition flag may relate to whether no-picture partitioning is applied to the current picture. That is, the no-picture partition flag may indicate/indicate whether no-picture partitioning is applied to the current picture.

For example, the no-picture partition flag may be expressed in the form of a no_pic_partition_flag syntax element. For example, the no_pic_partition_flag syntax element may specify whether no-picture partitioning is applied to the current picture.

The rectangular slice related information may include CTU size information. For example, the CTU size information may be related to the size of the luma coding tree block for the CTU. That is, the CTU size information may indicate/represent the size of the luma coding tree block for the CTU.

For example, the CTU size information may be expressed in the form of a pps_log2_ctu_size_minus5 syntax element. For example, the value +5 of the pps_log2_ctu_size_minus5 syntax element may specify the size of the luma coding tree block for each CTU.

The rectangular slice related information may include information on the number of tile columns. For example, the tile column number information may be related to the number of explicitly provided tile column widths. That is, the tile column number information may indicate/represent the number of explicitly provided tile column widths.

For example, the tile column number information may be expressed in the form of a num_exp_tile_columns_minus1 syntax element. For example, the value +1 of the num_exp_tile_columns_minus1 syntax element may specify the number of explicitly provided tile column widths.

The rectangular slice related information may include information on the number of tile rows. For example, the tile row number information may be related to the number of explicitly provided tile row heights. That is, the tile row number information may indicate/represent the number of explicitly provided tile row heights.

For example, the tile row number information may be expressed in the form of a num_exp_tile_rows_minus1 syntax element. For example, the value +1 of the num_exp_tile_rows_minus1 syntax element may specify the number of explicitly provided tile row heights.

The rectangular slice related information may include tile column width information. For example, the tile column width information may be related to the tile column width in units of coding tree blocks. That is, the tile column width information may indicate/represent the tile column width in units of coding tree blocks.

For example, the tile column width information may be expressed in the form of a tile_column_width_minus1 syntax element. For example, the value +1 of the tile_column_width_minus1 syntax element may specify the tile column width in units of coding tree blocks.

The rectangular slice related information may include tile row height information. For example, the tile row height information may be related to the tile row height in units of coding tree blocks. That is, the tile row height information may indicate/represent the tile row height in units of coding tree blocks.

For example, the tile row height information may be expressed in the form of a tile_row_height_minus1 syntax element. For example, the value +1 of the tile_row_height_minus1 syntax element may specify the tile row height in units of coding tree blocks.

The rectangular slice related information may include a rectangular slice flag. For example, the rectangular slice flag may relate to whether tiles in a slice constitute a rectangular region of a picture. In addition, the rectangular slice flag may be related to whether or not to signal layout information of the rectangular slice. That is, the rectangular slice flag may indicate/indicate whether tiles in a slice constitute a rectangular region of a picture. Also, the rectangular slice flag may indicate/indicate whether or not to signal layout information of a rectangular slice.

For example, the rectangular slice flag may be expressed in the form of a rect_slice_flag syntax element. For example, the rect_slice_flag syntax element may specify whether tiles in a slice constitute a rectangular region of a picture and whether layout information of a rectangular slice is signaled.

The rectangular slice related information may include a single slice flag. For example, the single slice flag may relate to whether a subpicture consists of only one slice. That is, the single slice flag may indicate/indicate whether a subpicture consists of only one slice.

For example, the single slice flag may be expressed in the form of a single_slice_per_subpic_flag syntax element. For example, the single_slice_per_subpic_flag syntax element may specify whether a subpicture consists of only one slice.

The rectangular slice related information may include information on the number of slices in a picture. For example, the slice number information in the picture may be related to the number of rectangular slices present in the picture. That is, the slice number information in the picture may indicate/represent the number of rectangular slices present in the picture.

For example, information on the number of slices in the picture is num_slices_in_pic_minus1 It can be expressed in the form of a syntax element. For example, the num_slices_in_pic_minus1 The value +1 of the syntax element may specify the number of rectangular slices present in the picture.

The rectangular slice related information may include tile delta length information and tile delta absolute value information. For example, the tile delta length information may be related to the number of bits of the tile delta absolute value information. That is, the tile delta length information may indicate/represent the number of bits of the tile delta absolute value information. For example, the value plus 1 of the tile delta length information may be equal to the number of bits of the tile delta absolute value information.

For example, the tile delta length information may be expressed in the form of a slice_bottom_right_delta_tile_idx_len_minus1 syntax element. For example, the value +1 of the slice_bottom_right_delta_tile_idx_len_minus1 syntax element may specify the number of bits of the tile delta absolute value information.

The tile delta absolute value information may be related to a lower right tile index of a slice. For example, the tile delta absolute value information may be related to an absolute value of a difference value between lower right tile indices of two slices. That is, the tile delta absolute value information may indicate/represent an absolute value of a difference value between the lower right tile indices of two slices.

For example, the tile delta absolute value information is slice_bottom_right_abs_delta_tile_idx It can be expressed in the form of a syntax element. For example, the slice_bottom_right_abs_delta_tile_idx The syntax element may specify the absolute value of the difference value between the lower right tile indices of the two slices.

The rectangular slice related information may include a tile delta code flag. For example, the tile delta code flag may be related to a lower right tile index of a slice. For example, the tile delta code flag may be related to a sign of a difference value between lower right tile indices of two slices. That is, the tile delta code flag may indicate/indicate a sign of a difference value between the lower right tile indices of two slices.

For example, the tile delta sign flag may be expressed in the form of a slice_bottom_right_tile_delta_sign_flag syntax element. For example, the slice_bottom_right_tile_delta_sign_flag syntax element may specify a sign of a difference value between lower right tile indices of two slices.

In this case, for example, when the value of the tile delta code flag is 1, the difference between the lower right tile indices of the two slices may have a positive value, and when the value of the tile delta code flag is 0, A difference value between the lower right tile indices of the two slices may have a negative value.

The rectangular slice related information may include information on the number of slices in a tile. For example, the information on the number of slices in a tile may be related to the number of slices existing in a tile when a slice includes some CTU rows belonging to one tile. That is, when the slice includes some CTU rows belonging to one tile, the information on the number of slices in the tile may indicate/represent the number of slices present in the tile.

For example, information on the number of slices in the tile is num_slices_in_tile_minus1 It can be expressed in the form of a syntax element. For example, the num_slices_in_tile_minus1 The value +1 of the syntax element may specify the number of slices present in a tile when the slice includes some CTU rows belonging to one tile.

The rectangular slice related information may include CTU unit slice height information. For example, the slice height information per CTU may be related to the height of a rectangular slice in units of CTU rows when the slice includes some CTU rows belonging to one tile. That is, the slice height information per CTU may indicate/represent the height of a rectangular slice in units of CTU rows when the slice includes some CTU rows belonging to one tile.

For example, the CTU unit slice height information is slice_height_in_ctu_minus1 It can be expressed in the form of a syntax element. For example, the slice_height_in_ctu_minus1 The value +1 of the syntax element may specify the height of the rectangular slice in units of CTU rows when the slice includes some CTU rows belonging to one tile.

The rectangular slice related information may include a loop filter tile availability flag. For example, the loop filter tile availability flag may be related to whether an in-loop filtering operation is available at a boundary of a tile. That is, the loop filter tile availability flag may indicate/indicate whether the in-loop filtering operation is available at the boundary of the tile.

For example, the loop filter tile enable flag may be expressed in the form of a loop_filter_across_tiles_enabled_flag syntax element. For example, the loop_filter_across_tiles_enabled_flag syntax element may specify whether an in-loop filtering operation is available at a boundary of a corresponding tile.

The rectangular slice related information may include a loop filter slice availability flag. For example, the loop filter slice availability flag may be related to whether an in-loop filtering operation is available at the boundary of a slice. That is, the loop filter slice availability flag may indicate/indicate whether the in-loop filtering operation is available at the boundary of the slice.

For example, the loop filter slice enable flag may be expressed in the form of a loop_filter_across_slices_enabled_flag syntax element. For example, the loop_filter_across_slices_enabled_flag syntax element may specify whether an in-loop filtering operation is available at a boundary of a corresponding slice.

For example, according to the embodiment, a picture parameter set (PPS) may include the syntax shown in Table 3 below. The syntax of Table 3 below may be a part of the PPS.

Here, the semantics of the syntax elements included in the syntax of Table 3 may be expressed, for example, as shown in Table 4 below.

That is, the no_pic_partition_flag syntax element may indicate whether no-picture partitioning is applied to the current picture based on whether the value is 0 or 1. The no_pic_partition_flag syntax element may be referred to as the no-picture partition flag and may be signaled through the PPS.

The value +5 of the pps_log2_ctu_size_minus5 syntax element may indicate the size of the luma coding tree block for the CTU. The pps_log2_ctu_size_minus5 syntax element may be referred to as the CTU size information and may be signaled through the PPS.

The value +1 of the num_exp_tile_columns_minus1 syntax element may indicate the number of explicitly provided tile column widths. The num_exp_tile_columns_minus1 syntax element may be referred to as the tile column number information and may be signaled through the PPS.

The value +1 of the num_exp_tile_rows_minus1 syntax element may indicate the number of explicitly provided tile row heights. The num_exp_tile_rows_minus1 syntax element may be referred to as the tile row number information and may be signaled through the PPS.

A value +1 of the tile_column_width_minus1 syntax element may indicate a tile column width in units of coding tree blocks. The tile_column_width_minus1 syntax element may be referred to as the tile column width information and may be signaled through the PPS.

A value +1 of the tile_row_height_minus1 syntax element may indicate a tile row height in units of coding tree blocks. The tile_row_height_minus1 syntax element may be referred to as the tile row height information and may be signaled through the PPS.

The rect_slice_flag syntax element may indicate whether tiles in a slice constitute a rectangular region of a picture and whether layout information of a rectangular slice is signaled. The rect_slice_flag syntax element may be referred to as the rectangular slice flag and may be signaled through the PPS.

The single_slice_per_subpic_flag syntax element may indicate whether a subpicture consists of only one slice. The single_slice_per_subpic_flag syntax element may be referred to as the single slice flag and may be signaled through the PPS.

The num_slices_in_pic_minus1 The value +1 of the syntax element may indicate the number of rectangular slices present in the picture. The num_slices_in_pic_minus1 The syntax element may be referred to as information on the number of slices in the picture, and may be signaled through the PPS.

The value +1 of the slice_bottom_right_delta_tile_idx_len_minus1 syntax element may indicate the number of bits of the tile delta absolute value information. The slice_bottom_right_delta_tile_idx_len_minus1 syntax element may be referred to as the tile delta length information and may be signaled through the PPS.

The slice_bottom_right_abs_delta_tile_idx The value of the syntax element may indicate an absolute value of a difference value between the lower right tile indices of the two slices. The slice_bottom_right_abs_delta_tile_idx The syntax element may be referred to as the tile delta absolute value information and may be signaled through the PPS.

The slice_bottom_right_tile_delta_sign_flag syntax element may indicate a sign of a difference value between lower right tile indices of two slices. The slice_bottom_right_tile_delta_sign_flag syntax element may be referred to as the tile delta sign flag and may be signaled through the PPS.

The num_slices_in_tile_minus1 The value +1 of the syntax element may indicate the number of slices present in a tile when the slice includes some CTU rows belonging to one tile. The num_slices_in_tile_minus1 The syntax element may be referred to as information on the number of slices in the tile and may be signaled through the PPS.

The slice_height_in_ctu_minus1 The value +1 of the syntax element may indicate the height of the rectangular slice in units of CTU rows when the slice includes some CTU rows belonging to one tile. The slice_height_in_ctu_minus1 The syntax element may be referred to as the CTU unit slice height information, and may be signaled through the PPS.

The loop_filter_across_tiles_enabled_flag syntax element may indicate whether an in-loop filtering operation is available at a boundary of a tile. The loop_filter_across_tiles_enabled_flag syntax element may be referred to as the loop filter tile enable flag, and may be signaled through the PPS.

The loop_filter_across_slices_enabled_flag syntax element may indicate whether an in-loop filtering operation is available at the boundary of a slice. The loop_filter_across_slices_enabled_flag syntax element may be referred to as the loop filter slice enable flag, and may be signaled through the PPS.

According to the embodiment, when the value of the no-picture partition flag is not 1, the CTU size information, the tile column number information, the tile row number information, the tile column width information, the tile row height information, The rectangular slice flag, the single slice flag, the number of slices in the picture information, the tile delta length information, the tile delta absolute value information, the tile delta code flag, the slice number information in the tile, the slice height information per CTU, The loop filter tile availability flag and the loop filter slice availability flag may be configured/included in the PPS and signaled. On the other hand, when the value of the no-picture partition flag is 1, the CTU size information, the tile column number information, the tile row number information, the tile column width information, the tile row height information, the rectangular slice flag, and the Single slice flag, the number of slices in the picture information, the tile delta length information, the tile delta absolute value information, the tile delta code flag, the slice number information in the tile, the slice height information per CTU, the loop filter tile availability flag and the loop filter slice availability flag may not exist in the PPS.

In this case, for example, the tile column width information may exist for each tile column based on the tile column number information. For example, the tile row height information may exist for each tile row based on the tile row number information.

For example, when the value of the rectangular slice flag is 1, the single slice flag may be configured/included in the PPS and signaled. When the value of the rectangular slice flag is not 1, the single slice flag may not exist in the PPS.

For example, when the value of the single slice flag is not 1, the slice number information in the picture, the tile delta length information, the tile delta absolute value information, the tile delta code flag, the slice number information in the tile, and the CTU unit Slice height information may be configured/included in the PPS and signaled. When the value of the single slice flag is 1, information on the number of slices in the picture, the tile delta length information, the absolute tile delta value information, the tile delta code flag, information on the number of slices in the tile, and the slice height information per CTU may not exist in the PPS.

In this case, for example, the tile delta absolute value information, the tile delta code flag, the slice number information in the tile, and the slice height information per CTU may be present for each slice in the picture based on the slice number information in the picture. have.

For example, when the slice width in units of tiles is derived as 1 and the slice height in units of tiles is derived as 1, the slice number information in the tile and the slice height information in the CTU unit may be configured/included in the PPS and signaled. . When the slice width in tile units is not derived as 1 or the slice height in tile units is not derived as 1, the slice number information in the tile and the slice height information in the CTU unit may not exist in the PPS.

Here, the slice width in units of the tile and the slice height in units of the tile may be predetermined to have a value of at least 1. For example, a slice width of 1 in units of tiles may mean that 1 or less tile columns exist in a slice. That is, when the slice width in units of the tile is 1, it may mean that one or more slice widths exist in the tile. Similarly, a slice height of 1 in units of tiles may mean that 1 or less tile rows exist in a slice. That is, when the slice height in units of the tile is 1, it may mean that one or more slice heights exist in the tile.

In this case, for example, the CTU unit slice height information may exist for each slice in the tile based on information on the number of slices in the tile.

In this way, when the value of the single slice flag is not 1, information on the number of slices in the picture, information on the tile delta length, information on the absolute tile delta value, the tile delta code flag, information on the number of slices in the tile, and the CTU unit At least one rectangular slice existing in the current picture may be derived based on the slice height information.

According to an existing embodiment, when the value of the single slice flag is not 1, after signaling the number of slices in the picture, slice width information (slice_width_in_tiles_minus1) for each slice based on the information on the number of slices in the picture. syntax element) and tile-unit slice height information (slice_height_in_tiles_minus1 syntax element) are signaled. In this case, when the value of the slice width information per tile is 0 and the value of the slice height information per tile is 0, information on the number of slices in the tile and slice height information per CTU are signaled.

In addition, when the value of the single slice flag is not 1, a tile index delta presence flag (tile_idx_delta_present_flag syntax element) is signaled, and if the value of the tile index delta presence flag is 1, tile index delta information (tile_idx_delta syntax element) signaled.

In contrast, according to the other embodiment proposed in this document, when the value of the single slice flag is not 1, after signaling the number of slices in the picture, each slice based on the information on the number of slices in the picture The tile delta length information, the tile delta absolute value information, and the tile delta code flag may be signaled.

That is, according to the other embodiment, in order to signal information related to the layout of each rectangular slice existing in a picture, the tile delta length information and the tile instead of the slice width information per tile and the slice height information per tile Delta absolute value information and the tile delta code flag may be signaled.

In addition, according to another embodiment, the slice width in units of tiles and the slice height in units of tiles may be derived through the equations shown in Table 4 without checking the slice width information per tile and the slice height information per tile. can

In the case of the other embodiment, as compared with the existing embodiment, a smaller number of bits can be allocated to signal information related to the layout of each rectangular slice present in the picture, thereby increasing overall coding efficiency. effect can be shown.

According to another embodiment proposed in this document, the rectangular slice related information may be signaled as follows.

First, the rectangular slice related information may include at most one tile flag. For example, the at most one tile flag may relate to whether a slice is a rectangular slice and is composed of one tile or CTUs that are part of a tile. That is, the at most one tile flag may indicate/indicate whether a slice is a rectangular slice and is composed of one tile or CTUs that are part of a tile.

For example, the at most one tile flag may be expressed in the form of a max_one_tile_per_slice_flag syntax element. For example, the max_one_tile_per_slice_flag syntax element may specify whether a slice is a rectangular slice and is composed of one tile or CTUs that are part of a tile.

The rectangular slice related information may include information on the number of slice signals. For example, the slice signal number information may be related to information for deriving the number of rectangular slices in a picture. That is, the slice signal number information may indicate/represent information for deriving the number of rectangular slices in a picture.

For example, the slice signal number information may be expressed in the form of a num_slices_signalled syntax element. For example, the num_slices_signalled syntax element may specify information for deriving the number of rectangular slices in a picture.

The rectangular slice related information may include a tile index delta presence flag. For example, the tile index delta presence flag may be related to whether tile index delta information is signaled. That is, the tile index delta presence flag may indicate/indicate whether the tile index delta information is signaled.

For example, the tile index delta presence flag may be expressed in the form of a tile_idx_delta_present_flag syntax element. For example, the tile_idx_delta_present_flag syntax element may specify whether to signal the tile index delta information.

The rectangular slice related information may include tile-unit slice width information. For example, the slice width information per tile may be related to the slice width in units of tile columns. That is, the slice width information per tile may indicate/represent the slice width in units of tile columns.

For example, the tile-unit slice width information may be expressed in the form of a slice_width_in_tiles_minus1 syntax element. For example, the value +1 of the slice_width_in_tiles_minus1 syntax element may specify the slice width in units of tile columns.

The rectangular slice-related information may include tile-unit slice height information. For example, the slice height information per tile may be related to the slice height in units of tile rows. That is, the slice height information per tile may indicate/represent the slice height in units of tile rows.

For example, the tile-unit slice height information may be expressed in the form of a slice_height_in_tiles_minus1 syntax element. For example, the value +1 of the slice_height_in_tiles_minus1 syntax element may specify the slice height in units of tile rows.

The rectangular slice related information may include tile index delta information. For example, the tile index delta information may be related to a difference value between tile indices including the first CTU of two slices. That is, the tile index delta information may indicate/represent a difference value between tile indices including the first CTU of two slices.

For example, the tile index delta information may be expressed in the form of a tile_idx_delta syntax element. For example, the tile_idx_delta syntax element may specify a difference value between tile indices including the first CTU of two slices.

For example, according to the embodiment, the PPS may include the syntax of Table 5 below. The syntax of Table 5 below may be a part of the PPS.

Here, the semantics of the syntax elements included in the syntax of Table 5 may be expressed, for example, as shown in Table 6 below.

That is, the max_one_tile_per_slice_flag syntax element may indicate whether a slice is a rectangular slice based on whether the value is 0 or 1 and is composed of one tile or CTUs that are part of a tile. The max_one_tile_per_slice_flag syntax element may be referred to as the at most one tile flag and may be signaled through the PPS.

The num_slices_signalled syntax element may indicate information for deriving the number of rectangular slices in a picture. The num_slices_signalled syntax element may be referred to as the slice signal number information and may be signaled through the PPS.

The tile_idx_delta_present_flag syntax element may indicate whether the tile index delta information is signaled based on whether the value is 0 or 1. The tile_idx_delta_present_flag syntax element may be referred to as the tile index delta presence flag, and may be signaled through the PPS.

A value +1 of the slice_width_in_tiles_minus1 syntax element may indicate a slice width in units of tile columns. The slice_width_in_tiles_minus1 syntax element may be referred to as the tile-unit slice width information, and may be signaled through the PPS.

A value +1 of the slice_height_in_tiles_minus1 syntax element may indicate a slice height in units of tile rows. The slice_height_in_tiles_minus1 syntax element may be referred to as the tile unit slice height information, and may be signaled through the PPS.

The tile_idx_delta syntax element may indicate a difference value between tile indices including the first CTU of two slices. The tile_idx_delta syntax element may be referred to as the tile index delta information and may be signaled through the PPS.

According to the embodiment, when the value of the no-picture partition flag is not 1, the CTU size information, the tile column number information, the tile row number information, the tile column width information, the tile row height information, The maximum one tile flag, the rectangular slice flag, the single slice flag, the slice signal number information, the tile index delta presence flag, the tile-unit slice width information, the tile-unit slice height information, the number of slices in the tile information, The CTU unit slice height information, the tile index delta information, the loop filter tile available flag, and the loop filter slice available flag may be configured/included in the PPS and signaled. On the other hand, when the value of the no-picture partition flag is 1, the CTU size information, the tile column number information, the tile row number information, the tile column width information, the tile row height information, the maximum one tile flag, The rectangular slice flag, the single slice flag, the slice signal number information, the tile index delta presence flag, the tile-unit slice width information, the tile-unit slice height information, the number of slices in the tile information, the CTU-unit slice height information , the tile index delta information, the loop filter tile availability flag, and the loop filter slice availability flag may not exist in the PPS.

In this case, for example, the tile column width information may exist for each tile column based on the tile column number information. For example, the tile row height information may exist for each tile row based on the tile row number information.

For example, when the value of the at most one tile flag is 1, the rectangular slice flag may be configured/included in the PPS and signaled. When the value of the at most one tile flag is not 1, the rectangular slice flag may not exist in the PPS. For example, when the rectangular slice flag does not exist, the value of the rectangular slice flag may be derived as 1.

For example, when the value of the rectangular slice flag is 1, the single slice flag may be configured/included in the PPS and signaled. When the value of the rectangular slice flag is not 1, the single slice flag may not exist in the PPS.

For example, when the value of the single slice flag is not 1, the slice signal number information, the tile index delta presence flag, the tile unit slice width information, the tile unit slice height information, the slice number information in the tile, and the CTU The unit slice height information and the tile index delta information may be configured/included in the PPS and signaled. On the other hand, when the value of the single slice flag is 1, the slice signal number information, the tile index delta presence flag, the tile unit slice width information, the tile unit slice height information, the slice number information in the tile, and the CTU unit The slice height information and the tile index delta information may not exist in the PPS.

In this case, for example, when the value of the at most one tile flag is not 1, the tile index delta presence flag may be configured/included in the PPS and signaled. When the value of the at most one tile flag is 1, the tile index delta presence flag may not exist in the PPS.

For example, when the value of the tile index delta presence flag is 1, the tile index delta information may be configured/included in the PPS and signaled. When the value of the tile index delta presence flag is not 1, the tile index delta information may not exist in the PPS.

Also, for example, if the slice signal number information is configured/included in the PPS and signaled, the number of slices in the picture may be derived based on the value of the slice signal number information as shown in Table 6 above.

In this case, the tile unit slice width information, the tile unit slice height information, the number of slices in the tile information, the CTU unit slice height information, and the tile index delta information are in the picture based on the derived number of slices in the picture. It may exist for each slice.

In this case, for example, when the value of the maximum one tile flag is not 1 and the number of tile columns is not derived as 1, the tile-unit slice width information may be configured/included in the PPS and signaled. When the value of the maximum one tile flag is 1 or the number of tile columns is derived as 1, the slice width information per tile may not exist in the PPS. When the slice width information per tile does not exist in the PPS, the value of the slice width information per tile may be derived as 0.

Similarly, when the value of the maximum one tile flag is not 1 and the number of tile rows is not derived as 1, the tile-unit slice height information may be configured/included in the PPS and signaled. When the value of the maximum one tile flag is 1 or the number of tile rows is derived as 1, the slice height information per tile may not exist in the PPS. When the slice height information per tile does not exist in the PPS, the value of the slice height information per tile may be derived as 0.

Also, for example, the number of slices in the tile and the slice height information per CTU are configured in the PPS when the value of the slice width information per tile is 0 and the value of the slice height information per tile is 0. may be included and signaled. When the value of the tile-unit slice width information is not 0 or the value of the tile-unit slice height information is not 0, the slice number information in the tile and the slice height information in the CTU unit may not exist in the PPS.

In this case, for example, the CTU unit slice height information may exist for each slice based on the slice number information in the tile.

According to the conventional embodiment described above, when the value of the single slice flag is not 1, after signaling the number of slices in the picture, the tile unit slice for each slice based on the information on the number of slices in the picture Width information and slice height information per tile were signaled. In this case, when the value of the slice width information per tile is 0 and the value of the slice height information per tile is 0, information on the number of slices in the tile and slice height information per CTU are signaled.

In addition, when the value of the single slice flag is not 1, the tile index delta presence flag is signaled. When the value of the tile index delta presence flag is 1, the tile index delta information is signaled.

In contrast, according to the other embodiment proposed in this document, when the value of the single slice flag is not 1, the value of the at most one tile flag is 1 based on the number of slices present in the picture. If not and the number of tile columns is not 1, the tile unit slice width information may be signaled. In addition, when the value of the single slice flag is not 1, based on the number of slices present in the picture, when the value of the at most one tile flag is not 1 and the number of tile rows is not 1, the tile unit slice Height information may be signaled.

In addition, when the value of the single slice flag is not 1, based on the number of slices present in the picture, when the value of the at most one tile flag is not 1, the tile index delta presence flag and the tile index delta information can be signaled.

That is, according to the other embodiment, the tile unit slice width information, the tile unit slice height information, the tile index delta presence flag, and the tile index delta information can be signaled under a specific condition based on the at most one tile flag. have.

Through this, in the case of the other embodiment, compared to the existing embodiment, a smaller number of bits can be allocated to signal information related to the layout of each rectangular slice present in the picture, so that the overall coding It can have the effect of increasing the efficiency.

The following drawings were created to explain a specific example of the present specification. Since the names of specific devices described in the drawings or the names of specific signals/messages/fields are presented by way of example, the technical features of the present specification are not limited to the specific names used in the following drawings.

10 and 11 schematically show an example of a video/image encoding method and related components according to embodiment(s) of this document. The method disclosed in FIG. 10 may be performed by the encoding apparatus disclosed in FIG. 2 . Specifically, for example, S1000 and S1010 of FIG. 10 may be performed by the image dividing unit 210 of the encoding apparatus, and S1020 of FIG. 10 may be performed by the entropy encoding unit 240 of the encoding apparatus. have. The method disclosed in FIG. 10 may include the embodiments described above in this document.

Referring to FIG. 10 , the encoding apparatus derives at least one sub-picture for the current picture ( S1000 ). The encoding apparatus may divide the input image (or picture, frame) into predetermined units. For example, the encoding apparatus may divide the input image into sub-pictures, slices, and/or tiles. For example, the encoding apparatus may divide the input image into rectangular slices and/or raster scan slices. In this case, as an example, when the current picture is divided into at least one subpicture, the encoding apparatus may derive at least one subpicture constituting the current picture. Also, as an example, when the current picture is divided into at least one rectangular slice, the encoding apparatus may derive at least one rectangular slice constituting the current picture.

The encoding apparatus generates subpicture related information based on the at least one subpicture (S1010). For example, the subpicture-related information includes at least one of a subpicture presence flag, subpicture number information, CTU delta length information, CTU delta absolute value information, CTU delta sign information, picture handling flag, and loop filter subpicture availability flag. can do. For example, the subpicture-related information may include at least one of subpics_present_flag, sps_num_subpics_minus1, sps_subpic_ctu_bottom_right_delta_len_minus1, subpic_ctu_delta_bottom_right_idx, subpic_ctu_delta_bottom_right_sign_filter_as_subpic_treated_enabled elements of at least one of the following elements.

In this case, for example, the encoding apparatus may additionally generate rectangular slice related information based on the at least one rectangular slice. For example, rectangular slice related information includes no-picture partition flag, CTU size information, tile column number information, tile row number information, tile column width information, tile row height information, rectangular slice flag, single slice flag, slice within a picture. It may include at least one of number information, tile delta length information, tile delta absolute value information, tile delta code flag, number of slices in tile information, CTU unit slice height information, loop filter tile available flag, and loop filter slice available flag. . For example, a rectangular slice related information no_pic_partition_flag, pps_log2_ctu_size_minus5, num_exp_tile_columns_minus1, num_exp_tile_rows_minus1, tile_column_width_minus1, tile_row_height_minus1, rect_slice_flag, single_slice_per_subpic_flag, num_slices_in_pic_minus1, slice_bottom_right_delta_tile_idx_len_minus1, slice_bottom_right_abs_delta_tile_idx, slice_bottom_right_tile_delta_sign_flag, num_slices_in_tile_minus1, slice_height_in_ctu_minus1, loop_filter_across_tiles_enabled_flag, loop_filter_across_slices_enabled_flag It may include at least one of the syntax elements.

The encoding device encodes the video/image information (S1020). The video/image information may include the sub-picture related information. The video/image information may further include information related to the rectangular slice. Also, the video/image information may include various information according to an embodiment of the present document. For example, the video/image information may include information disclosed in at least one of Tables 1, 3, and/or 5 described above.

The encoded video/image information may be output in the form of a bitstream. The bitstream may be transmitted to the decoding device through a network or a storage medium.

Specifically, the sub-picture related information may include various information according to an embodiment of the present document.

For example, the subpicture related information may include CTU delta length information and CTU delta absolute value information. For example, the CTU delta length information may be related to the number of bits of the CTU delta absolute value information. That is, the CTU delta length information may indicate/represent the number of bits of the CTU delta absolute value information. For example, the value plus 1 of the CTU delta length information may be equal to the number of bits of the CTU delta absolute value information.

For example, the CTU delta length information may be represented in the form of a sps_subpic_ctu_bottom_right_delta_len_minus1 syntax element. For example, the value +1 of the sps_subpic_ctu_bottom_right_delta_len_minus1 syntax element may specify the number of bits of the CTU delta absolute value information.

The CTU delta absolute value information may be related to the lower right CTU index of the subpicture. For example, the CTU delta absolute value information may be related to the absolute value of the difference between the lower right CTU indices of the two subpictures. That is, the CTU delta absolute value information may indicate/represent the absolute value of the difference between the lower right CTU indices of the two subpictures.

For example, the CTU delta absolute value information may be represented in the form of a subpic_ctu_abs_delta_bottom_right_idx syntax element. For example, the subpic_ctu_abs_delta_bottom_right_idx syntax element may specify an absolute value of a difference value between lower-right CTU indices of two sub-pictures.

The subpicture related information may include a CTU delta code flag. For example, the CTU delta code flag may be related to the lower right CTU index of the subpicture. For example, the CTU delta code flag may be related to a sign of a difference value between lower right CTU indices of two subpictures. That is, the CTU delta code flag may indicate/indicate a sign of a difference value between the lower right CTU indexes of two subpictures.

For example, the CTU delta sign flag may be represented in the form of a subpic_ctu_delta_bottom_right_sign_flag syntax element. For example, the subpic_ctu_delta_bottom_right_sign_flag syntax element may specify a sign of a difference value between lower-right CTU indices of two sub-pictures.

At this time, for example, when the value of the CTU delta code flag is 1, the difference value between the lower right CTU indices of the two subpictures may have a positive value, and when the value of the CTU delta code flag is 0 , a difference value between the lower right CTU indices of the two subpictures may have a negative value.

The at least one subpicture in the current picture may be derived based on the CTU delta length information, the CTU delta absolute value information, and the CTU delta code flag.

Specifically, the rectangular slice related information may include various information according to an embodiment of the present document.

The rectangular slice related information may include tile delta length information and tile delta absolute value information. For example, the tile delta length information may be related to the number of bits of the tile delta absolute value information. That is, the tile delta length information may indicate/represent the number of bits of the tile delta absolute value information. For example, the value plus 1 of the tile delta length information may be equal to the number of bits of the tile delta absolute value information.

For example, the tile delta length information may be expressed in the form of a slice_bottom_right_delta_tile_idx_len_minus1 syntax element. For example, the value +1 of the slice_bottom_right_delta_tile_idx_len_minus1 syntax element may specify the number of bits of the tile delta absolute value information.

The tile delta absolute value information may be related to a lower right tile index of a slice. For example, the tile delta absolute value information may be related to an absolute value of a difference value between lower right tile indices of two slices. That is, the tile delta absolute value information may indicate/represent an absolute value of a difference value between the lower right tile indices of two slices.

For example, the tile delta absolute value information is slice_bottom_right_abs_delta_tile_idx It can be expressed in the form of a syntax element. For example, the slice_bottom_right_abs_delta_tile_idx The syntax element may specify the absolute value of the difference value between the lower right tile indices of the two slices.

The rectangular slice related information may include a tile delta code flag. For example, the tile delta code flag may be related to a lower right tile index of a slice. For example, the tile delta code flag may be related to a sign of a difference value between lower right tile indices of two slices. That is, the tile delta code flag may indicate/indicate a sign of a difference value between the lower right tile indices of two slices.

For example, the tile delta sign flag may be expressed in the form of a slice_bottom_right_tile_delta_sign_flag syntax element. For example, the slice_bottom_right_tile_delta_sign_flag syntax element may specify a sign of a difference value between lower right tile indices of two slices.

In this case, for example, when the value of the tile delta code flag is 1, the difference between the lower right tile indices of the two slices may have a positive value, and when the value of the tile delta code flag is 0, A difference value between the lower right tile indices of the two slices may have a negative value.

The at least one rectangular slice in the current picture may be derived based on the tile delta length information, the tile delta absolute value information, and the tile delta code flag.

12 and 13 schematically show an example of a video/image decoding method and related components according to an embodiment of the present document. The method disclosed in FIG. 12 may be performed by the decoding apparatus illustrated in FIG. 3 . Specifically, for example, S1200 and S1210 of FIG. 12 may be performed by the entropy decoding unit 310 of the decoding apparatus, and S1220 of the decoding apparatus is a residual processing unit 320, a prediction unit 330 and/or Alternatively, it may be performed by at least one of the adder 340 . The method disclosed in FIG. 12 may include the embodiments described above in this document.

Referring to FIG. 12 , the decoding apparatus receives/obtains video/image information ( S1200 ). The decoding apparatus may receive/obtain the video/image information through a bitstream. The video/image information may include sub-picture related information. The video/image information may further include rectangular slice related information. Also, the video/image information may include various information according to an embodiment of the present document. For example, the video/image information may include information disclosed in at least one of Tables 1, 3, and/or 5 described above.

The decoding apparatus derives at least one sub-picture in the current picture based on the video/image information (S1210). For example, the decoding apparatus may derive at least one subpicture in the current picture based on subpicture related information included in the video/image information. Also, for example, the decoding apparatus may derive at least one rectangular slice in the current picture based on the rectangular slice related information included in the video/image information.

The decoding apparatus performs decoding on the current picture based on the at least one subpicture (S1220). Based on the at least one subpicture, the decoding apparatus may decode the current picture in units of subpictures. Also, the decoding apparatus may perform decoding on the current picture based on the at least one rectangular slice. Based on the at least one rectangular slice, the decoding apparatus may decode the current picture in units of rectangular slices. In this case, the above-described intra and inter prediction methods and residual processing methods may be applied.

Here, the sub-picture related information may include various information according to an embodiment of the present document.

The subpicture related information may include CTU delta length information and CTU delta absolute value information. For example, the CTU delta length information may be related to the number of bits of the CTU delta absolute value information. That is, the CTU delta length information may indicate/represent the number of bits of the CTU delta absolute value information. For example, the value plus 1 of the CTU delta length information may be equal to the number of bits of the CTU delta absolute value information.

For example, the CTU delta length information may be represented in the form of a sps_subpic_ctu_bottom_right_delta_len_minus1 syntax element. For example, the value +1 of the sps_subpic_ctu_bottom_right_delta_len_minus1 syntax element may specify the number of bits of the CTU delta absolute value information.

The CTU delta absolute value information may be related to the lower right CTU index of the subpicture. For example, the CTU delta absolute value information may be related to the absolute value of the difference between the lower right CTU indices of the two subpictures. That is, the CTU delta absolute value information may indicate/represent the absolute value of the difference between the lower right CTU indices of the two subpictures.

For example, the CTU delta absolute value information may be represented in the form of a subpic_ctu_abs_delta_bottom_right_idx syntax element. For example, the subpic_ctu_abs_delta_bottom_right_idx syntax element may specify an absolute value of a difference value between lower-right CTU indices of two sub-pictures.

The subpicture related information may include a CTU delta code flag. For example, the CTU delta code flag may be related to the lower right CTU index of the subpicture. For example, the CTU delta code flag may be related to a sign of a difference value between lower right CTU indices of two subpictures. That is, the CTU delta code flag may indicate/indicate a sign of a difference value between the lower right CTU indexes of two subpictures.

For example, the CTU delta sign flag may be represented in the form of a subpic_ctu_delta_bottom_right_sign_flag syntax element. For example, the subpic_ctu_delta_bottom_right_sign_flag syntax element may specify a sign of a difference value between lower-right CTU indices of two sub-pictures.

At this time, for example, when the value of the CTU delta code flag is 1, the difference value between the lower right CTU indices of the two subpictures may have a positive value, and when the value of the CTU delta code flag is 0 , a difference value between the lower right CTU indices of the two subpictures may have a negative value.

Meanwhile, the rectangular slice related information may include various information according to an embodiment of the present document.

The rectangular slice related information may include a rectangular slice flag. For example, the rectangular slice flag may relate to whether tiles in a slice constitute a rectangular region of a picture. In addition, the rectangular slice flag may be related to whether or not to signal layout information of the rectangular slice. That is, the rectangular slice flag may indicate/indicate whether tiles in a slice constitute a rectangular region of a picture. Also, the rectangular slice flag may indicate/indicate whether or not to signal layout information of a rectangular slice.

For example, the rectangular slice flag may be expressed in the form of a rect_slice_flag syntax element. For example, the rect_slice_flag syntax element may specify whether tiles in a slice constitute a rectangular region of a picture and whether layout information of a rectangular slice is signaled.

The rectangular slice related information may include a single slice flag. For example, the single slice flag may relate to whether a subpicture consists of only one slice. That is, the single slice flag may indicate/indicate whether a subpicture consists of only one slice.

For example, the single slice flag may be expressed in the form of a single_slice_per_subpic_flag syntax element. For example, the single_slice_per_subpic_flag syntax element may specify whether a subpicture consists of only one slice.

The rectangular slice related information may include tile delta length information and tile delta absolute value information. For example, the tile delta length information may be related to the number of bits of the tile delta absolute value information. That is, the tile delta length information may indicate/represent the number of bits of the tile delta absolute value information. For example, the value plus 1 of the tile delta length information may be equal to the number of bits of the tile delta absolute value information.

For example, the tile delta length information may be expressed in the form of a slice_bottom_right_delta_tile_idx_len_minus1 syntax element. For example, the value +1 of the slice_bottom_right_delta_tile_idx_len_minus1 syntax element may specify the number of bits of the tile delta absolute value information.

The tile delta absolute value information may be related to a lower right tile index of a slice. For example, the tile delta absolute value information may be related to an absolute value of a difference value between lower right tile indices of two slices. That is, the tile delta absolute value information may indicate/represent an absolute value of a difference value between the lower right tile indices of two slices.

For example, the tile delta absolute value information is slice_bottom_right_abs_delta_tile_idx It can be expressed in the form of a syntax element. For example, the slice_bottom_right_abs_delta_tile_idx The syntax element may specify the absolute value of the difference value between the lower right tile indices of the two slices.

The rectangular slice related information may include a tile delta code flag. For example, the tile delta code flag may be related to a lower right tile index of a slice. For example, the tile delta code flag may be related to a sign of a difference value between lower right tile indices of two slices. That is, the tile delta code flag may indicate/indicate a sign of a difference value between the lower right tile indices of two slices.

For example, the tile delta sign flag may be expressed in the form of a slice_bottom_right_tile_delta_sign_flag syntax element. For example, the slice_bottom_right_tile_delta_sign_flag syntax element may specify a sign of a difference value between lower right tile indices of two slices.

In this case, for example, when the value of the tile delta code flag is 1, the difference between the lower right tile indices of the two slices may have a positive value, and when the value of the tile delta code flag is 0, A difference value between the lower right tile indices of the two slices may have a negative value.

The rectangular slice related information may include information on the number of slices in a tile. For example, the information on the number of slices in a tile may be related to the number of slices existing in a tile when a slice includes some CTU rows belonging to one tile. That is, when the slice includes some CTU rows belonging to one tile, the information on the number of slices in the tile may indicate/represent the number of slices present in the tile.

For example, information on the number of slices in the tile is num_slices_in_tile_minus1 It can be expressed in the form of a syntax element. For example, the num_slices_in_tile_minus1 The value +1 of the syntax element may specify the number of slices present in a tile when the slice includes some CTU rows belonging to one tile.

The rectangular slice related information may include CTU unit slice height information. For example, the slice height information per CTU may be related to the height of a rectangular slice in units of CTU rows when the slice includes some CTU rows belonging to one tile. That is, the slice height information per CTU may indicate/represent the height of a rectangular slice in units of CTU rows when the slice includes some CTU rows belonging to one tile.

For example, the CTU unit slice height information is slice_height_in_ctu_minus1 It can be expressed in the form of a syntax element. For example, the slice_height_in_ctu_minus1 The value +1 of the syntax element may specify the height of the rectangular slice in units of CTU rows when the slice includes some CTU rows belonging to one tile.

When the value of the rectangular slice flag is 1, the single slice flag may be configured/included in the PPS and signaled. When the value of the single slice flag is not 1, information on the number of slices in the picture, the tile delta length information, the tile delta absolute value information, the tile delta code flag, information on the number of slices in the tile, and the slice height per CTU Information may be signaled by being configured/included in the PPS.

In this case, for example, the tile delta absolute value information, the tile delta code flag, the slice number information in the tile, and the slice height information per CTU may be present for each slice in the picture based on the slice number information in the picture. have.

For example, when the slice width in units of tiles is derived as 1 and the slice height in units of tiles is derived as 1, the slice number information in the tile and the slice height information in the CTU unit may be configured/included in the PPS and signaled. .

The rectangular slice related information may include at most one tile flag. For example, the at most one tile flag may relate to whether a slice is a rectangular slice and is composed of one tile or CTUs that are part of a tile. That is, the at most one tile flag may indicate/indicate whether a slice is a rectangular slice and is composed of one tile or CTUs that are part of a tile.

For example, the at most one tile flag may be expressed in the form of a max_one_tile_per_slice_flag syntax element. For example, the max_one_tile_per_slice_flag syntax element may specify whether a slice is a rectangular slice and is composed of one tile or CTUs that are part of a tile.

The rectangular slice related information may include information on the number of slice signals. For example, the slice signal number information may be related to information for deriving the number of rectangular slices in a picture. That is, the slice signal number information may indicate/represent information for deriving the number of rectangular slices in a picture.

For example, the slice signal number information may be expressed in the form of a num_slices_signalled syntax element. For example, the num_slices_signalled syntax element may specify information for deriving the number of rectangular slices in a picture.

The rectangular slice related information may include a tile index delta presence flag. For example, the tile index delta presence flag may be related to whether tile index delta information is signaled. That is, the tile index delta presence flag may indicate/indicate whether the tile index delta information is signaled.

For example, the tile index delta presence flag may be expressed in the form of a tile_idx_delta_present_flag syntax element. For example, the tile_idx_delta_present_flag syntax element may specify whether to signal the tile index delta information.

The rectangular slice related information may include tile-unit slice width information. For example, the slice width information per tile may be related to the slice width in units of tile columns. That is, the slice width information per tile may indicate/represent the slice width in units of tile columns.

For example, the tile-unit slice width information may be expressed in the form of a slice_width_in_tiles_minus1 syntax element. For example, the value +1 of the slice_width_in_tiles_minus1 syntax element may specify the slice width in units of tile columns.

The rectangular slice-related information may include tile-unit slice height information. For example, the slice height information per tile may be related to the slice height in units of tile rows. That is, the slice height information per tile may indicate/represent the slice height in units of tile rows.

For example, the tile-unit slice height information may be expressed in the form of a slice_height_in_tiles_minus1 syntax element. For example, the value +1 of the slice_height_in_tiles_minus1 syntax element may specify the slice height in units of tile rows.

The rectangular slice related information may include tile index delta information. For example, the tile index delta information may be related to a difference value between tile indices including the first CTU of two slices. That is, the tile index delta information may indicate/represent a difference value between tile indices including the first CTU of two slices.

For example, the tile index delta information may be expressed in the form of a tile_idx_delta syntax element. For example, the tile_idx_delta syntax element may specify a difference value between tile indices including the first CTU of two slices.

When the value of the at most one tile flag is 1, the rectangular slice flag may be configured/included in the PPS and signaled.

When the value of the at most one tile flag is not 1, the tile index delta presence flag may be configured/included in the PPS and signaled.

When the value of the maximum one tile flag is not 1 and the number of tile columns is not derived as 1, the slice width information per tile may be configured/included in the PPS and signaled.

When the value of the maximum one tile flag is not 1 and the number of tile rows is not derived from 1, the slice height information per tile may be configured/included in the PPS and signaled.

When the value of the maximum one tile flag is 1 or the number of tile columns is derived as 1, the slice width information per tile does not exist in the PPS, and the value of the slice width information per tile may be derived as 0. .

When the value of the maximum one tile flag is 1 or the number of tile rows is 1, the slice height information per tile does not exist in the PPS, and the value of the slice height information per tile may be derived as 0.

When the value of the rectangular slice flag is 1, a single slice flag related to whether a subpicture consists of only one slice may be configured/included in the PPS and signaled.

When the value of the single slice flag is not 1, slice signal number information for deriving the number of rectangular slices in a picture may be configured/included in the PPS and signaled.

In the above embodiment, the methods are described on the basis of a flowchart as a series of steps or blocks, but the embodiment is not limited to the order of the steps, and some steps may occur in a different order or at the same time as other steps as described above. can In addition, those skilled in the art will understand that the steps shown in the flowchart are not exclusive, other steps may be included, or one or more steps of the flowchart may be deleted without affecting the scope of the embodiments herein.

The method according to the above-described embodiments of the present document may be implemented in software form, and the encoding device and/or decoding device according to this document is, for example, an image of a TV, a computer, a smart phone, a set-top box, a display device, etc. It may be included in the device performing the processing.

When the embodiments in this document are implemented in software, the above-described method may be implemented as a module (process, function, etc.) performing the above-described function. A module may be stored in a memory and executed by a processor. The memory may be internal or external to the processor, and may be coupled to the processor by various well-known means. The processor may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and/or data processing devices. Memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and/or other storage devices. That is, the embodiments described in this document may be implemented and performed on a processor, a microprocessor, a controller, or a chip. For example, the functional units shown in each figure may be implemented and performed on a computer, a processor, a microprocessor, a controller, or a chip. In this case, information on instructions or an algorithm for implementation may be stored in a digital storage medium.

In addition, the decoding device and the encoding device to which the embodiment(s) of this document are applied is a multimedia broadcasting transmission/reception device, a mobile communication terminal, a home cinema video device, a digital cinema video device, a surveillance camera, a video conversation device, such as a video communication device. Real-time communication device, mobile streaming device, storage medium, camcorder, video on demand (VoD) service providing device, OTT video (over the top video) device, internet streaming service providing device, three-dimensional (3D) video device, virtual reality (VR) ) devices, AR (argumente reality) devices, video telephony video devices, transportation means (eg, vehicle (including autonomous vehicle) terminals, airplane terminals, ship terminals, etc.) and medical video devices, etc. It can be used to process signals. For example, the OTT video (Over the top video) device may include a game console, a Blu-ray player, an Internet-connected TV, a home theater system, a smart phone, a tablet PC, a digital video recorder (DVR), and the like.

In addition, the processing method to which the embodiment(s) of this document is applied may be produced in the form of a program executed by a computer, and may be stored in a computer-readable recording medium. Multimedia data having a data structure according to the embodiment(s) of this document may also be stored in a computer-readable recording medium. The computer-readable recording medium includes all kinds of storage devices and distributed storage devices in which computer-readable data is stored. The computer-readable recording medium includes, for example, Blu-ray Disc (BD), Universal Serial Bus (USB), ROM, PROM, EPROM, EEPROM, RAM, CD-ROM, magnetic tape, floppy disk and optical It may include a data storage device. In addition, the computer-readable recording medium includes a medium implemented in the form of a carrier wave (eg, transmission through the Internet). In addition, the bitstream generated by the encoding method may be stored in a computer-readable recording medium or transmitted through a wired/wireless communication network.

In addition, the embodiment(s) of this document may be implemented as a computer program product by program code, and the program code may be executed in a computer by the embodiment(s) of this document. The program code may be stored on a carrier readable by a computer.

14 shows an example of a content streaming system to which embodiments disclosed in this document can be applied.

Referring to FIG. 14 , a content streaming system to which embodiments of this document 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.

The encoding server compresses content input from multimedia input devices such as a smart phone, a camera, a camcorder, etc. into digital data to generate a bitstream and transmits it to the streaming server. As another example, when multimedia input devices such as a smartphone, a camera, a camcorder, etc. directly generate a bitstream, the encoding server may be omitted.

The bitstream may be generated by an encoding method or a bitstream generating method to which embodiments of this document are applied, and the streaming server may temporarily store the bitstream in the process of transmitting or receiving the bitstream.

The streaming server transmits multimedia data to the user device based on a user's request through the web server, and the web server serves as a medium informing the user of any service. When a user requests a desired service from the web server, the web server transmits it to a streaming server, and the streaming server transmits multimedia data to the user. In this case, the content streaming system may include a separate control server. In this case, the control server serves to control commands/responses between devices in the content streaming system.

The streaming server may receive content from a media repository and/or an encoding server. For example, when content is received from the encoding server, the content may be received in real time. In this case, in order to provide a smooth streaming service, the streaming server may store the bitstream for a predetermined time.

Examples of the user device include a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate PC, Tablet PC (tablet PC), ultrabook (ultrabook), wearable device (e.g., watch-type terminal (smartwatch), glass-type terminal (smart glass), HMD (head mounted display)), digital TV, desktop There may be a computer, digital signage, and the like.

Each server in the content streaming system may be operated as a distributed server, and in this case, data received from each server may be distributed and processed.

The claims described herein may be combined in various ways. For example, the technical features of the method claims of the present specification may be combined and implemented as an apparatus, and the technical features of the apparatus claims of the present specification may be combined and implemented as a method. In addition, the technical features of the method claim of the present specification and the technical features of the apparatus claim may be combined to be implemented as an apparatus, and the technical features of the method claim of the present specification and the technical features of the apparatus claim may be combined and implemented as a method.

Claims (15)

1. In the image decoding method performed by the decoding device,

   obtaining image information through a bitstream, wherein the image information includes sub-picture-related information related to a sub-picture existing in the picture;

   deriving at least one sub picture in the current picture based on the sub picture related information; and

   Comprising performing decoding on the current picture based on the at least one sub picture,

   The subpicture-related information includes CTU delta absolute value information for the lower right coding tree unit (CTU) index of the subpicture, and the CTU delta absolute value information is a difference value between the lower right CTU indices of two consecutive subpictures. is related to the absolute value of

   Based on the CTU delta absolute value information, the upper left CTU position of the subpicture, the width of the subpicture and the height of the subpicture are derived,

   The at least one subpicture in the current picture is derived based on the upper-left CTU position of the subpicture, the width of the subpicture, and the height of the subpicture.
2. According to claim 1,

   The image decoding method, characterized in that the upper-left CTU of the first sub-picture in the current picture is located at the coordinates of (0, 0) of the current picture.
3. According to claim 1,

   The subpicture related information includes CTU delta length information, and the CTU delta length information relates to the number of bits of the CTU delta absolute value information,

   The value of the CTU delta length information plus 1 is the same as the number of bits of the CTU delta absolute value information, the video decoding method.
4. According to claim 1,

   The subpicture related information includes a CTU delta code flag for the lower right CTU index of the subpicture, and the CTU delta code flag is related to the sign of the difference value between the lower right CTU indices of two consecutive subpictures,

   The at least one subpicture is derived based on the CTU delta code flag,

   Based on the case where the value of the CTU delta code flag is 1, the difference value between the lower right CTU indices of the two subpictures has a positive value,

   Based on the case where the value of the CTU delta code flag is 0, the difference value between the lower right CTU indices of the two subpictures is characterized in that it has a negative value.
5. According to claim 1,

   The image information further includes rectangular slice related information related to a rectangular slice existing in the picture,

   The video decoding method is

   The method further comprises deriving at least one rectangular slice in the current picture based on the rectangular slice related information,

   The decoding of the current picture comprises performing decoding on the current picture based on the at least one rectangular slice.
6. 6. The method of claim 5,

   The rectangular slice-related information includes tile delta absolute value information for a lower right tile index of a slice, and the tile delta absolute value information relates to an absolute value of a difference value between lower right tile indices of two consecutive slices;

   The at least one rectangular slice is derived based on the tile delta absolute value information,

   The rectangular slice related information includes a rectangular slice flag related to whether tiles in a slice constitute a rectangular region of a picture and whether or not to signal layout information of a rectangular slice,

   Based on the case where the value of the rectangular slice flag is 1, a single slice flag related to whether a subpicture consists of only one slice is included in a picture parameter set (PPS),

   Based on a case in which the value of the single slice flag is not 1, the tile delta absolute value information is included in the PPS.
7. 6. The method of claim 5,

   The rectangular slice related information includes at most one tile flag related to whether the slice is a rectangular slice and is composed of one tile or CTUs that are part of a tile,

   Based on a case in which the value of the at most one tile flag is 1, a rectangular slice flag related to whether tiles in a slice constitute a rectangular area of a picture and whether or not to signal layout information of a rectangular slice is a picture parameter set (Picture parameter set). , PPS),

   Based on a case in which the value of the at most one tile flag is not 1, a tile index delta presence flag related to whether tile index delta information is signaled is included in the PPS,

   Based on a case in which the value of the at most one tile flag is not 1 and the number of tile columns is not derived as 1, tile-unit slice width information related to the tile-column-unit slice width is included in the PPS,

   Based on a case in which the value of the at most one tile flag is not 1 and the number of tile rows is not derived as 1, slice height information per tile related to the slice height in units of tile rows is included in the PPS, characterized in that , video decoding method.
8. 7. The method of claim 6,

   The rectangular slice related information includes tile delta length information, and the tile delta length information relates to the number of bits of the tile delta absolute value information,

   The value plus 1 of the tile delta length information is equal to the number of bits of the tile delta absolute value information,

   Based on a case in which the value of the single slice flag is not 1, the tile delta length information is included in the PPS.
9. 7. The method of claim 6,

   The rectangular slice-related information includes a tile delta code flag for a slice lower right tile index, and the tile delta code flag relates to a sign of a difference value between the lower right tile indices of two consecutive slices,

   The at least one rectangular slice is derived based on the tile delta sign flag,

   Based on a case in which the value of the single slice flag is not 1, the tile delta code flag is included in the PPS.
10. 10. The method of claim 9,

    Based on the case where the value of the tile delta code flag is 1, the difference value between the lower right tile indices of two consecutive slices has a positive value,

    Based on a case in which the value of the tile delta code flag is 0, a difference value between the lower right tile indices of two consecutive slices has a negative value.
11. 7. The method of claim 6,

    Based on the case where the value of the single slice flag is not 1, CTU unit slice height information is included in the PPS,

    Based on a case in which the slice width in units of tile is derived as 1 and the slice height in units of tile is derived as 1, the slice height information in units of CTU is characterized in that it is included in the PPS, video decoding method
12. 8. The method of claim 7,

    Based on a case in which the value of the at most one tile flag is 1 or the number of tile columns is derived as 1, the tile-unit slice width information does not exist in the PPS, and the value of the tile-unit slice width information is derived as 0 becomes,

    Based on a case in which the value of the maximum one tile flag is 1 or the number of tile rows is derived as 1, the tile-unit slice height information is not present in the PPS, and the value of the tile-unit slice height information is 0. An image decoding method, characterized in that derived.
13. 8. The method of claim 7,

    Based on the case where the value of the rectangular slice flag is 1, a single slice flag related to whether a subpicture consists of only one slice is included in the PPS,

    Based on a case in which the value of the single slice flag is not 1, slice signal number information for deriving the number of rectangular slices in a picture is included in the PPS.
14. In the video encoding method performed by the encoding device,

    deriving at least one sub-picture for the current picture;

    generating subpicture related information based on the at least one subpicture; and

    Encoding video information including the sub-picture related information,

    The subpicture-related information includes CTU delta absolute value information for the lower right coding tree unit (CTU) index of the subpicture, and the CTU delta absolute value information is a difference value between the lower right CTU indices of two consecutive subpictures. An image encoding method, characterized in that it relates to the absolute value of .
15. A computer readable digital storage medium storing encoded information causing a decoding apparatus to perform an image decoding method, the image decoding method comprising:

    obtaining image information through the encoded information, wherein the image information includes sub-picture-related information related to a sub-picture existing in a picture;

    deriving at least one sub picture in the current picture based on the sub picture related information; and

    Comprising performing decoding on the current picture based on the at least one sub picture,

    The subpicture-related information includes CTU delta absolute value information for the lower right coding tree unit (CTU) index of the subpicture, and the CTU delta absolute value information is a difference value between the lower right CTU indices of two consecutive subpictures. is related to the absolute value of

    Based on the CTU delta absolute value information, the upper left CTU position of the subpicture, the width of the subpicture and the height of the subpicture are derived,

    Based on the upper-left CTU position of the subpicture, the width of the subpicture and the height of the subpicture, the at least one subpicture in the current picture is derived.

Images