KR20250001975A - Image decoding method and apparatus using inter picture prediction - Google Patents

Abstract

A method and device for decoding an image using inter-screen prediction are disclosed. The method for decoding an image using inter-screen prediction includes the steps of receiving a bitstream, obtaining a part of information indicating a motion vector of a current block to be decoded from the received bitstream, using the obtained information to determine remaining information excluding the part, thereby obtaining a motion vector of the current block, and generating a prediction block of the current block through inter-screen prediction using the motion vector of the current block. Therefore, the efficiency of image encoding and decoding can be improved.

Description

{IMAGE DECODING METHOD AND APPARATUS USING INTER PICTURE PREDICTION}

The present invention relates to a method and device for video decoding using inter-screen prediction, and more particularly, to a technology for reducing the number of data or bits exchanged between an encoding device and a decoding device by determining the remaining information using only a part of information indicating the size, sign, and optimal motion vector of the difference value of a motion vector when encoding and decoding a motion vector required for inter-screen prediction of a current block.

The ISO/ISE MPEG (Moving Picture Experts Group) and the ITU-T VCEG (Video Coding Experts Group) organized the Joint Collaborative Team on Video Coding (JCV-VC) and established the ISO/IEC MPEG-H HEVC (High Efficiency Video Coding)/ITU-T H.265 video compression standard in January 2013. In addition, in order to respond to the trend toward popularizing high-definition video due to the rapid development of information and communication technology, ISO/ISE MPEG and ITU-T VCEG organized the Joint Video Exploration Team (JVET) at the 22nd JCT-VC Geneva meeting and are actively working to establish next-generation video compression technology standards for UHD (Ultra High Definition) video compression that is clearer than HD (High Definition) video.

Meanwhile, according to existing video compression standard technology, the amount of data to be encoded is reduced by generating a prediction block for the current block to be encoded and encoding the differential value between the prediction block and the current block. Such prediction technology includes an intra-screen prediction method that generates a prediction block for the current block by utilizing the similarity with spatially adjacent blocks within the same screen, and an inter-screen prediction method that generates a prediction block for the current block by utilizing the similarity with blocks of temporally adjacent screens.

At this time, inter-screen prediction uses motion vectors as information indicating blocks with similarity within screens temporally adjacent to the current block. At this time, since the bit value may be very large if the motion vector is encoded as it is, the encoding device configures candidate motion vectors using the motion vectors of neighboring blocks adjacent to the current block, and encodes the difference value between the optimal motion vector selected from among the candidate motion vectors and the motion vector of the current block and transmits it to the decoding device.

However, even when encoding the difference between the optimal motion vector and the motion vector of the current block, the effect of reducing bit consumption is minimal if the optimal motion vector is significantly different from the motion vector of the current block. Therefore, a method is needed to reduce the amount of information transmitted between the encoding device and the decoding device in order to improve the efficiency of image encoding and decoding.

The purpose of the present invention to solve the above problems is to provide a video decoding method using inter-screen prediction.

Another object of the present invention to solve the above problems is to provide an image decoding device using inter-screen prediction.

One aspect of the present invention to achieve the above object provides a method for decoding an image using inter-screen prediction.

Here, a method for decoding a video using inter-screen prediction may include a step of receiving a bitstream, a step of obtaining a part of information indicating a motion vector of a current block to be decoded from the received bitstream, a step of obtaining a motion vector of the current block by determining the remaining information excluding the part using the obtained information, and a step of generating a prediction block of the current block through inter-screen prediction using the motion vector of the current block.

Here, the information indicating the motion vector of the current block may include at least one of the size of the difference between the optimal motion vector selected from among two or more candidate motion vectors and the motion vector of the current block, the sign of the difference, and information indicating the optimal motion vector.

Here, the step of obtaining the motion vector of the current block may include the step of determining whether the size of the difference value corresponds to a preset condition, and if the size corresponds to the preset condition, the step of determining the sign of the difference value based on the optimal motion vector obtained from the information indicating the optimal motion vector.

Here, the preset condition may be set based on the interval between adjacent vectors among the two or more candidate motion vectors.

Here, the step of determining whether the size of the difference value corresponds to a preset condition may include the step of deriving a value having the largest interval between the adjacent vectors and a value having the smallest interval between the adjacent vectors, and the step of comparing the largest value and the smallest value with the size of the difference value.

Here, the preset condition can be set based on an interval that divides the interval between adjacent vectors in half.

Here, the step of obtaining the motion vector of the current block may include the step of obtaining the differential value using the magnitude of the differential value and the sign of the differential value, the step of determining an estimated motion vector of the current block by adding a first candidate motion vector among the two or more candidate motion vectors to the obtained differential value, the step of determining whether the estimated motion vector has a coordinate value that is closest to the first candidate motion vector among the two or more candidate motion vectors, and the step of determining the optimal motion vector based on the determination result.

Here, the step of determining the estimated motion vector and the step of judging can be repeatedly performed by substituting the remaining candidate motion vectors excluding the first candidate motion vector into the first candidate motion vector.

In this step of determining the optimal motion vector, if there is only one candidate motion vector having the closest coordinate value as a result of the iterative execution, the candidate motion vector can be determined as the optimal motion vector.

Here, the step of obtaining the motion vector of the current block may include the step of determining whether the size of the difference value corresponds to a preset condition, and if the preset condition corresponds, the step of excluding at least one motion vector among the two or more candidate motion vectors from the candidate motion vectors and determining the optimal motion vector among the remaining candidate motion vectors.

Another aspect of the present invention to achieve the above object provides a video decoding device using inter-screen prediction.

Here, a video decoding device using inter-screen prediction may include at least one processor and a memory storing instructions that instruct the at least one processor to perform at least one step.

Here, at least one of the steps may include: receiving a bitstream; obtaining a portion of information indicating a motion vector of a current block to be decoded from the received bitstream; determining the remaining information excluding the portion by using the obtained information to obtain the motion vector of the current block; and generating a prediction block of the current block through inter-screen prediction using the motion vector of the current block.

Here, the information indicating the motion vector of the current block may include at least one of the size of the difference between the optimal motion vector selected from among two or more candidate motion vectors and the motion vector of the current block, the sign of the difference, and information indicating the optimal motion vector.

Here, the step of obtaining the motion vector of the current block may include the step of determining whether the size of the difference value corresponds to a preset condition, and if the size corresponds to the preset condition, the step of determining the sign of the difference value based on the optimal motion vector obtained from the information indicating the optimal motion vector.

Here, the preset condition may be set based on the interval between adjacent vectors among the two or more candidate motion vectors.

Here, the step of determining whether the size of the difference value corresponds to a preset condition may include the step of deriving a value having the largest interval between the adjacent vectors and a value having the smallest interval between the adjacent vectors, and the step of comparing the largest value and the smallest value with the size of the difference value.

Here, the preset condition can be set based on an interval that divides the interval between adjacent vectors in half.

Here, the step of obtaining the motion vector of the current block may include the step of obtaining the differential value using the magnitude of the differential value and the sign of the differential value, the step of determining an estimated motion vector of the current block by adding a first candidate motion vector among the two or more candidate motion vectors to the obtained differential value, the step of determining whether the estimated motion vector has a coordinate value that is closest to the first candidate motion vector among the two or more candidate motion vectors, and the step of determining the optimal motion vector based on the determination result.

Here, the step of determining the estimated motion vector and the step of judging can be repeatedly performed by substituting the remaining candidate motion vectors excluding the first candidate motion vector into the first candidate motion vector.

In this step of determining the optimal motion vector, if there is only one candidate motion vector having the closest coordinate value as a result of the iterative execution, the candidate motion vector can be determined as the optimal motion vector.

Here, the step of obtaining the motion vector of the current block may include the step of determining whether the size of the difference value corresponds to a preset condition, and if the preset condition corresponds, the step of excluding at least one motion vector among the two or more candidate motion vectors from the candidate motion vectors and determining the optimal motion vector among the remaining candidate motion vectors.

When using the image decoding method and device using inter-screen prediction according to the present invention as described above, the number of bits consumed in the encoding and decoding process can be reduced.

Therefore, there is an advantage that the image compression ratio can be improved.

FIG. 1 is a conceptual diagram of an image encoding and decoding system according to an embodiment of the present invention.
FIG. 2 is a block diagram of an image encoding device according to one embodiment of the present invention.
FIG. 3 is a configuration diagram of an image decoding device according to one embodiment of the present invention.
FIG. 4 is an exemplary diagram illustrating a method for determining a candidate motion vector for setting a motion vector of a current block in inter-screen prediction according to one embodiment of the present invention.
Figure 5 is an example diagram showing an area where the motion vector of the current block can exist when there are two candidate motion vectors.
Figure 6 is a first example diagram showing an area where the motion vector of the current block can exist when there are three candidate motion vectors.
Figure 7 is a second example diagram showing an area where the motion vector of the current block can exist when there are three candidate motion vectors.
FIG. 8 is a flowchart of a video decoding method using inter-screen prediction according to one embodiment of the present invention.
FIG. 9 is a configuration diagram of an image decoding device using inter-screen prediction according to one embodiment of the present invention.

The present invention can have various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention. In describing each drawing, similar reference numerals are used for similar components.

The terms first, second, A, B, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are only used to distinguish one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and/or includes any combination of a plurality of related described items or any item among a plurality of related described items.

When it is said that a component is "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components in between. On the other hand, when it is said that a component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

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

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms defined in commonly used dictionaries, such as those defined in common dictionaries, should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly defined in this application.

Typically, an image can be composed of a series of still images, and these still images can be divided into GOP (Group of Pictures) units, and each still image can be referred to as a picture. At this time, the picture can represent one of a frame or a field in a progressive signal or an interlace signal, and when encoding/decoding is performed in frame units, the image can be represented as a 'frame', and when performed in field units, the image can be represented as a 'field'. The present invention assumes and explains a progressive signal, but it can also be applied to an interlace signal. As upper concepts, there can be units such as GOP and sequence, and furthermore, each picture can be divided into predetermined areas such as slices, tiles, and blocks. Further, one GOP can include units such as I picture, P picture, and B picture. An I picture may refer to a picture that is encoded/decoded on its own without using a reference picture, and a P picture and a B picture may refer to a picture that is encoded/decoded by performing processes such as motion estimation and motion compensation using a reference picture. In general, for a P picture, an I picture and a P picture can be used as reference pictures, and for a B picture, an I picture and a P picture can be used as reference pictures, but this definition above may also change depending on the encoding/decoding settings.

Here, a picture referred to for encoding/decoding is called a reference picture, and a block or pixel referred to is called a reference block or reference pixel. In addition, the referenced data may be not only a pixel value in the spatial domain, but also a coefficient value in the frequency domain, and various encoding/decoding information generated and determined during the encoding/decoding process. For example, the referenced data may include prediction-related information or motion-related information within the screen in the prediction unit, transformation-related information in the transformation unit/inverse transformation unit, quantization-related information in the quantization unit/inverse quantization unit, encoding/decoding-related information (context information) in the encoding unit/decoding unit, and filter-related information in the in-loop filter unit.

The minimum unit that constitutes an image can be a pixel, and the number of bits used to express one pixel is called bit depth. Generally, the bit depth can be 8 bits, and a higher bit depth can be supported depending on the encoding setting. The bit depth can support at least one bit depth depending on the color space. In addition, it can be composed of at least one color space depending on the color format of the image. Depending on the color format, it can be composed of one or more pictures having a certain size or one or more pictures having different sizes. For example, in the case of YCbCr 4:2:0, it can be composed of one luminance component (Y in this example) and two chrominance components (Cb/Cr in this example), and in this case, the composition ratio of the chrominance component and the luminance component can have a horizontal and vertical ratio of 1:2. As another example, in the case of 4:4:4, it can have the same composition ratio for the horizontal and vertical. When a picture is composed of one or more color spaces as in the above example, division into each color space can be performed.

In the present invention, the description will be made based on some color spaces (Y in this example) of some color formats (YCbCr in this example), and the same or similar application (settings dependent on a specific color space) can be made to other color spaces (Cb, Cr in this example) according to the color format. However, it may also be possible to have partial differences (settings independent on a specific color space) for each color space. That is, the settings dependent on each color space can mean having settings proportional to or dependent on the composition ratio of each component (for example, determined according to 4:2:0, 4:2:2, 4:4:4, etc.), and the independent settings for each color space can mean having settings only for the corresponding color space regardless of or independently of the composition ratio of each component. In the present invention, some components can have independent settings or dependent settings depending on the encoder/decoder.

The configuration information or syntax elements required in the video encoding process can be determined at the unit level of video, sequence, picture, slice, tile, block, etc., and can be included in the bitstream and transmitted to the decoder as units such as VPS (Video Parameter Set), SPS (Sequence Parameter Set), PPS (Picture Parameter Set), Slice Header, Tile Header, and Block Header, and the decoder can parse the configuration information transmitted from the encoder at the same level to use it in the video decoding process. In addition, related information can be transmitted as a bitstream in the form of SEI (Supplement Enhancement Information) or metadata and can be parsed and used. Each parameter set has a unique ID value, and a lower parameter set can have an ID value of an upper parameter set to be referenced. For example, a lower parameter set can reference information of an upper parameter set having a matching ID value among one or more upper parameter sets. Among the various examples of units mentioned above, if one unit contains one or more other units, the corresponding unit can be called a parent unit, and the contained units can be called child units.

In the case of setting information occurring in the above unit, it may include content about independent settings for each unit, or content about settings that are dependent on previous, subsequent, or upper units. Here, the dependent setting may be understood as indicating the setting information of the unit with flag information that follows the settings of the previous, subsequent, or upper units (for example, a 1-bit flag, 1 if followed, 0 if not followed). The setting information in the present invention will be explained focusing on examples of independent settings, but examples of addition or replacement with content about a dependent relationship on setting information of previous, subsequent units or upper units of the current unit may also be included.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings.

FIG. 1 is a conceptual diagram of an image encoding and decoding system according to an embodiment of the present invention.

Referring to FIG. 1, the image encoding device (105) and the decoding device (100) may be user terminals such as a personal computer (PC), a notebook computer, a personal digital assistant (PDA), a portable multimedia player (PMP), a PlayStation Portable (PSP), a wireless communication terminal, a smart phone, a TV, etc., or server terminals such as an application server and a service server, and may include various devices including a communication device such as a communication modem for performing communication with various devices or wired/wireless communication networks, a memory (120, 125) for storing various programs and data for inter- or intra-prediction for encoding or decoding images, a processor (110, 115) for executing programs and performing calculations and controls, etc. In addition, the image encoded into a bitstream by the image encoding device (105) may be transmitted to the image decoding device (100) through a wired or wireless communication network such as the Internet, a local area network, a wireless LAN, a WiBro network, a mobile communication network, etc. in real time or non-real time, or through various communication interfaces such as a cable, a universal serial bus (USB), etc., and may be decoded in the image decoding device (100) to be restored into an image and played back. In addition, the image encoded into a bitstream by the image encoding device (105) may be transmitted from the image encoding device (105) to the image decoding device (100) through a computer-readable recording medium.

FIG. 2 is a block diagram of an image encoding device according to one embodiment of the present invention.

The video encoding device (20) according to the present embodiment may include, as shown in FIG. 2, a prediction unit (200), a subtraction unit (205), a transformation unit (210), a quantization unit (215), an inverse quantization unit (220), an inverse transformation unit (225), an addition unit (230), a filter unit (235), a decoding picture buffer (240), and an entropy encoding unit (245).

The prediction unit (200) may include an intra-screen prediction unit that performs intra-screen prediction and an inter-screen prediction unit that performs inter-screen prediction. Intra-screen prediction may generate a prediction block by performing spatial prediction using pixels of adjacent blocks of a current block, and inter-screen prediction may generate a prediction block by finding an area that best matches the current block from a reference image and performing motion compensation. It may be determined whether to use intra-screen prediction or inter-screen prediction for the corresponding unit (encoding unit or prediction unit), and specific information (e.g., intra-screen prediction mode, motion vector, reference image, etc.) according to each prediction method may be determined. At this time, the processing unit where prediction is performed and the processing unit where the prediction method and specific contents are determined may be determined according to the encoding/decoding settings. For example, the prediction method, the prediction mode, etc. may be determined by the prediction unit, and the prediction may be performed by the transformation unit.

The subtraction unit (205) generates a residual block by subtracting the prediction block from the current block. That is, the subtraction unit (205) calculates the difference between the pixel value of each pixel of the current block to be encoded and the predicted pixel value of each pixel of the prediction block generated through the prediction unit, and generates a residual block, which is a residual signal in the form of a block.

The transformation unit (210) transforms the residual block into a frequency domain and transforms each pixel value of the residual block into a frequency coefficient. Here, the transformation unit (210) can transform the residual signal into a frequency domain by using various transformation techniques that transform a spatial axis image signal into a frequency domain, such as a Hadamard transform, a DCT-based transform, a DST-based transform, and a KLT-based transform. The residual signal transformed into the frequency domain becomes a frequency coefficient. The transformation can be performed by a one-dimensional transformation matrix. Each transformation matrix can be adaptively used in horizontal and vertical units. For example, in the case of intra-screen prediction, if the prediction mode is horizontal, a DCT-based transformation matrix may be used in the vertical direction, and a DST-based transformation matrix may be used in the horizontal direction. If it is vertical, a DCT-based transformation matrix may be used in the horizontal direction, and a DST-based transformation matrix may be used in the vertical direction.

The quantization unit (215) quantizes the residual block having frequency coefficients converted into the frequency domain by the transformation unit (210). Here, the quantization unit (215) can quantize the converted residual block using dead zone uniform threshold quantization, quantization weighted matrix, or a quantization technique that is an improved version thereof. One or more quantization techniques can be candidates and can be determined by information about the encoding mode, prediction mode, etc.

The entropy encoding unit (245) scans the generated quantized frequency coefficient series according to various scan methods to generate a quantized coefficient series, and encodes the same using an entropy encoding technique, etc. to output the same. The scan pattern can be set to one of various patterns such as zigzag, diagonal, and raster.

The inverse quantization unit (220) inversely quantizes the residual block quantized by the quantization unit (215). That is, the quantization unit (220) inversely quantizes the quantized frequency coefficient series to generate a residual block having frequency coefficients.

The inverse transform unit (225) inversely transforms the residual block inversely quantized by the inverse quantization unit (220). That is, the inverse transform unit (225) inversely transforms the frequency coefficients of the inverse quantized residual block to generate a residual block having pixel values, i.e., a restored residual block. Here, the inverse transform unit (225) can perform inverse transformation by inversely using the transformation method used in the transformation unit (210).

The addition unit (230) adds the prediction block predicted by the prediction unit (200) and the residual block restored by the inverse transformation unit (225) to restore the current block. The restored current block is stored as a reference picture (or reference block) in the decoding picture buffer (240) and can be used as a reference picture when encoding the next block of the current block or other blocks or other pictures in the future.

The filter unit (235) may include one or more post-processing filter processes such as a deblocking filter, a Sample Adaptive Offset (SAO), and an Adaptive Loop Filter (ALF). The deblocking filter may remove block distortion occurring at the boundary between blocks in a restored picture. The ALF may perform filtering based on a value obtained by comparing a restored image with an original image after the block is filtered through the deblocking filter. The SAO may restore an offset difference from the original image on a pixel basis for a residual block to which the deblocking filter is applied, and may be applied in the form of a band offset, an edge offset, etc. Such a post-processing filter may be applied to a restored picture or block.

The decoded picture buffer (240) can store a block or picture restored through the filter unit (235). The restored block or picture stored in the decoded picture buffer (240) can be provided to a prediction unit (200) that performs intra-screen prediction or inter-screen prediction.

Although not shown in the drawing, further divisions may be included, and the divisions may be used to divide the encoding units into various sizes. At this time, the encoding unit may be composed of a plurality of encoding blocks (for example, one luminance encoding block, two chrominance encoding blocks, etc.) depending on the color format. For convenience of explanation, one color component unit is assumed and explained. The encoding block may have a variable size such as M×M (for example, M is 4, 8, 16, 32, 64, 128, etc.). Alternatively, depending on the division method (for example, tree-based division, quad-tree division, binary tree division, etc.), the encoding block may have a variable size such as M×N (for example, M and N are 4, 8, 16, 32, 64, 128, etc.). At this time, the encoding block may be a unit that serves as the basis for intra-screen prediction, inter-screen prediction, transformation, quantization, entropy encoding, etc. Although the present invention is described under the assumption that multiple sub-blocks having the same size and shape are obtained depending on the partitioning method, it may also be applied to cases having asymmetrical sub-blocks (for example, in the case of a binary tree, 4M × 4N is partitioned into 3M × 4N and M × 4N or 4M × 3N and 4M × N, etc.). In this case, the asymmetrical sub-blocks may be supported by information for which support is additionally determined according to the encoding/decoding settings in the partitioning method for obtaining symmetrical sub-blocks.

The division of an encoding block (M × N) can have a recursive tree-based structure. At this time, whether or not to divide can be indicated by a division flag (e.g., a quad tree division flag, a binary division flag). For example, if the division flag of an encoding block with a division depth (Depth) of k is 0, encoding of the encoding block is performed in an encoding block with a division depth of k, and if the division flag of an encoding block with a division depth of k is 1, encoding of the encoding block is performed in four sub-coding blocks (quad tree division) or two sub-coding blocks (binary tree division) with a division depth of k+1 depending on the division method. At this time, the size of the block can be (M >> 1) × (N >> 1) for four encoding blocks, and (M >> 1) × N or M × (N >> 1) for two encoding blocks. The above sub-coding block can be set as an encoding block (k+1) again and split into sub-coding blocks (k+2) through the above process. At this time, in the case of quad tree splitting, one splitting flag (e.g., a splitting or not flag) can be supported, and in the case of binary tree splitting, at least one (at most two) flags (e.g., in addition to the splitting or not flag, a splitting direction flag <horizontal or vertical. May be omitted in some cases depending on the preceding upper or previous splitting result>) can be supported.

Block splitting can start from the maximum coding block and proceed to the minimum coding block. Alternatively, it can start from the minimum splitting depth and proceed to the maximum splitting depth. That is, splitting can be performed recursively until the size of the block reaches the minimum coding block size or the splitting depth reaches the maximum splitting depth. At this time, the size of the maximum coding block, the size of the minimum coding block, and the maximum splitting depth can be adaptively set according to the encoding/decoding settings (e.g., image <slice, tile> type <I/P/B>, encoding mode <Intra/Inter>, chrominance component <Y/Cb/Cr>, etc.). For example, when the maximum coding block is 128×128, quad tree splitting can be performed in the range of 8×8 to 128×128, and binary tree splitting can be performed in the range of 4×4 to 32×32 and when the maximum splitting depth is 3. Alternatively, quad tree partitioning can be performed in the range of 8×8 to 128×128, and binary tree partitioning can be performed in the range of 4×4 to 128×128 and with a maximum partition depth of 3. In the former case, it can be a setting in I picture type (e.g., slice), and in the latter case, it can be a setting in P or B picture type. As described in the above example, partitioning settings such as the size of the maximum coding block, the size of the minimum coding block, the maximum partitioning depth, etc. can be common or supported individually depending on the partitioning method.

When multiple partitioning methods are supported, partitioning is performed within the block support range of each partitioning method, and when the block support ranges of each partitioning method overlap, there may be a priority of the partitioning methods. For example, quad tree partitioning may precede binary tree partitioning. In addition, when multiple partitioning methods are supported, whether to perform a subsequent partitioning may be determined based on the result of the preceding partitioning. For example, when the result of the preceding partitioning indicates that the partitioning is performed, the subsequent partitioning may not be performed, and the sub-coding block partitioned according to the preceding partitioning may be set as an encoding block again to perform the partitioning.

Alternatively, if the result of the preceding split indicates that splitting is not performed, splitting can be performed according to the result of the succeeding split. At this time, if the result of the succeeding split indicates that splitting is performed, the split sub-coding block can be set to an encoding block again to perform splitting, and if the result of the succeeding split indicates that splitting is not performed, no further splitting is performed. At this time, when the result of the succeeding split indicates that splitting is performed and the split sub-coding block is set to an encoding block again in a case where multiple splitting methods are supported, only the succeeding splitting can be supported and the preceding splitting is not performed. That is, if multiple splitting methods are supported and the result of the preceding split indicates that splitting is not performed, the preceding splitting is no longer performed.

For example, if an M x N coding block can be split into quad-tree split and binary tree split, a quad-tree split flag can be checked first, and if the split flag is 1, splitting is performed into four sub-coding blocks of the size of (M >> 1) x (N >> 1), and the sub-coding blocks are set as coding blocks again to perform splitting (quad-tree splitting or binary tree splitting). If the split flag is 0, a binary tree split flag can be checked, and if the flag is 1, splitting is performed into two sub-coding blocks of the size of (M >> 1) x N or M x (N >> 1), and the sub-coding blocks are set as coding blocks again to perform splitting (binary tree splitting). If the split flag is 0, the splitting process is terminated and encoding is performed.

Although the above example illustrates a case where multiple partitioning methods are performed, it is not limited thereto, and various combinations of partitioning methods may be supported. For example, partitioning methods such as quad tree/binary tree/quad tree + binary tree may be used. In this case, the basic partitioning method may be set to quad tree method, and the additional partitioning method may be set to binary tree method, and information on whether or not the additional partitioning method is supported may be explicitly included in units such as sequences, pictures, slices, and tiles.

In the above example, information related to segmentation, such as the size information of the encoding block, the supported range of the encoding block, and the maximum segmentation depth, may be included in units such as sequences, pictures, slices, and tiles, or may be implicitly determined. In summary, the range of allowable blocks may be determined by the maximum size of the encoding block, the supported range of blocks, and the maximum segmentation depth.

Through the above process, the obtained encoding block by performing the division can be set to the maximum size of intra-screen prediction or inter-screen prediction. That is, the encoding block after the block division can be the starting size of the division of the prediction block for intra-screen prediction or inter-screen prediction. For example, if the encoding block is 2M×2N, the prediction block can have a size of 2M×2N, M×N, which is equal to or smaller than that. Or, it can have a size of 2M×2N, 2M×N, M×2N, M×N. Or, it can have a size of 2M×2N, which is the same size as the encoding block. At this time, the fact that the encoding block and the prediction block have the same size can mean that prediction is performed with a size obtained through the division of the encoding block without performing the division of the prediction block. That is, it means that the division information for the prediction block is not generated. Such a setting can also be applied to the transformation block, and the transformation can be performed in units of the divided encoding blocks. That is, a square or rectangular block obtained according to the above division result may be a block used for intra-screen prediction, inter-screen prediction, and may be a block used for transformation and quantization of residual components.

FIG. 3 is a configuration diagram of an image decoding device according to one embodiment of the present invention.

Referring to FIG. 3, the image decoding device (30) may be configured to include an encoded picture buffer (300), an entropy decoding unit (305), a prediction unit (310), an inverse quantization unit (315), an inverse transformation unit (320), an adder/subtracter (325), a filter (330), and a decoded picture buffer (335).

Additionally, the prediction unit (310) may be configured to include an intra-screen prediction module and an inter-screen prediction module.

First, when an image bitstream transmitted from an image encoding device (20) is received, it can be stored in an encoded picture buffer (300).

The entropy decoding unit (305) can decode the bitstream to generate quantized coefficients, motion vectors, and other syntax. The generated data can be transmitted to the prediction unit (310).

The prediction unit (310) can generate a prediction block based on data transmitted from the entropy decoding unit (305). At this time, a reference picture list using a default configuration technique can be configured based on a reference image stored in the decoded picture buffer (335).

The inverse quantization unit (315) can inverse quantize the quantized transform coefficients decoded by the entropy decoding unit (305) provided as a bitstream.

The inverse transform unit (320) can generate a residual block by applying inverse DCT, inverse integer transform, or similar inverse transform techniques to the transform coefficients.

At this time, the inverse quantization unit (315) and the inverse transformation unit (320) perform the process performed in the transformation unit (210) and the quantization unit (215) of the image encoding device (20) described above in reverse, and can be implemented in various ways. For example, the same process and inverse transformation shared with the transformation unit (210) and the quantization unit (215) may be used, or the transformation and quantization process may be performed in reverse using information about the transformation and quantization process (e.g., transformation size, transformation shape, quantization type, etc.) from the image encoding device (20).

The residual block that has undergone the inverse quantization and inverse transformation process can be added to the prediction block derived by the prediction unit (310) to generate a restored image block. This addition can be performed by an adder/subtractor (325).

The filter (330) may apply a deblocking filter to the restored image block to remove blocking phenomenon as needed, and may additionally use other loop filters before and after the decoding process to improve video quality.

The restored and filtered image blocks can be stored in the decoded picture buffer (335).

FIG. 4 is an exemplary diagram illustrating a method for determining a candidate motion vector for setting a motion vector of a current block in inter-screen prediction according to one embodiment of the present invention.

In order to generate a prediction block of the current block, if a block similar to the current block is found in a block in a frame temporally different from the frame to which the current block belongs, a motion vector can be used as information indicating the block. At this time, if the coordinate value of the motion vector to be encoded is large, the bit loss rate can be very large. Therefore, the encoding device can select an optimal motion vector from among candidate motion vectors expected to have a high similarity to the motion vector to be encoded, and then transmit information indicating the optimal motion vector, a difference value between the motion vector to be encoded and the optimal motion vector, and a sign of the difference value to the decoding device. At this time, the optimal motion vector can be a motion vector having a minimum distance from the motion vector for the current block among the candidate motion vectors so that the difference value can be minimized.

Here, the problem is how to determine the candidate motion vector. Referring to Fig. 4, the motion vector of the neighboring block adjacent to the current block can be determined as the candidate motion vector. That is, the motion vectors of the neighboring blocks (A, B, C, D, E) adjacent to the current block (CURRENT BLOCK) are likely to be similar to the motion vector of the current block, so they can be determined as candidate motion vectors representing the motion vector of the current block.

In addition, the motion vector of a block (Co-located BLOCK) that is temporally adjacent to the frame (or picture) to which the current block belongs and is in the same position as the current block in a frame (or picture) whose encoding has been completed, as well as a neighboring block adjacent to the current block, can be determined as a candidate motion vector.

In addition, candidate motion vectors may be selected from two or more blocks among neighboring blocks or blocks that are temporally adjacent and located at the same position as the current block in frames whose encoding has been completed. At this time, the number of candidate motion vectors and the selection conditions of the candidate motion vectors may be preset in the encoding device and the decoding device.

Below, we will examine a case where the information indicating the optimal motion vector or the code for the differential value among the information indicating the optimal motion vector, the difference between the motion vector of the current block and the optimal motion vector, and the code for the differential value can be known by a decoding device, and based on this, we will explain a method of not encoding the information indicating the optimal motion vector or the code for the differential value.

Figure 5 is an example diagram showing an area where the motion vector of the current block can exist when there are two candidate motion vectors.

Referring to FIG. 5, it can be explained that when there are two candidate motion vectors, a case can be described where the decoding device can know the code for the information or differential value indicating the optimal motion vector. In addition, a and b can mean the x or y coordinate values for the candidate motion vectors, but are simply referred to as candidate motion vectors hereinafter.

First, when selecting an optimal motion vector from two candidate motion vectors a and b and encoding the difference (mvd, moving vector difference) between the optimal motion vector and the motion vector (k) of the current block, it is assumed that the difference (mvd) between the optimal motion vector and the motion vector (k) of the current block has a relationship as shown in the following mathematical expression 1.

In the relationship of the above mathematical expression 1, if the candidate motion vector a is the optimal motion vector, the motion vector (k) of the current block is based on the candidate motion vector a. (half of the distance between adjacent candidate motion vectors a and b) can be located at a greater distance than that. That is, the motion vector (k) of the current block can be located in the first area (51a) and the second area (52a) in FIG. 5. At this time, if the motion vector (k) of the current block is located in the second area (52a), it becomes closer to the candidate motion vector b than to the candidate motion vector a. If the motion vector (k) of the current block is closer to the candidate motion vector b than to the candidate motion vector a, the precondition that the optimal motion vector is a is violated, and therefore the motion vector (k) of the current block cannot be located in the second area (52a) and can be located in the first area (51a).

In addition, if the candidate motion vector b is the optimal motion vector in the relationship of the above mathematical expression 1, the motion vector (k) of the current block is based on the candidate motion vector b. can be located at a further distance. That is, the motion vector (k) of the current block can be located in the third area (51b) and the fourth area (52b) in Fig. 5. At this time, if the motion vector (k) of the current block is located in the third area (51b), it becomes closer to the candidate motion vector a than to the candidate motion vector b. If the motion vector (k) of the current block is closer to the candidate motion vector a than to the candidate motion vector b, the precondition that the optimal motion vector is b is violated, and therefore the motion vector (k) of the current block cannot be located in the third area (51b) and can be located in the fourth area (52b).

In summary, if mathematical expression 1 is satisfied, it can be known that the motion vector (k) of the current block is located in the first area (51a) or the fourth area (52b). Using this fact, information indicating the optimal motion vector can be omitted, or the sign for the difference between the optimal motion vector and the motion vector of the current block can be omitted.

Specifically, the method of omitting the sign of the difference between the optimal motion vector and the motion vector of the current block is as follows.

First, if we look at the case where a is the optimal motion vector, the motion vector (k) of the current block is located in the first region (51a). Therefore, if the optimal motion vector is a, the motion vector (k) of the current block is located to the left of a (a position with a smaller value than a), so we can see that the difference (k-a) between the motion vector (k) of the current block and the optimal motion vector (a in the precondition) is always negative.

Next, if we look at the case where b is the optimal motion vector, the motion vector (k) of the current block is located in the fourth region (52b). Therefore, if the optimal motion vector is b, the motion vector (k) of the current block is located to the right of b (a position with a larger value than b), so we can see that the difference (k-b) between the motion vector (k) of the current block and the optimal motion vector (b in the precondition) is always positive.

In summary, if the encoding device satisfies the mathematical expression 1, the process of transmitting the sign of the difference between the optimal motion vector and the motion vector of the current block to the decoding device can be omitted, and the size of the difference and the information indicating the optimal motion vector can be transmitted to the decoding device. The decoding device determines whether the mathematical expression 1 is satisfied, and if the optimal motion vector is a as a result of referring to the information indicating the optimal motion vector, the decoding device can determine that the sign of the difference is negative by determining that the motion vector (k) of the current block is located in the first area (51a). In addition, the decoding device determines whether the mathematical expression 1 is satisfied, and if the optimal motion vector is b as a result of referring to the information indicating the optimal motion vector, the decoding device can determine that the sign of the difference is positive by determining that the motion vector (k) of the current block is located in the fourth area (52b).

Meanwhile, the method of omitting information indicating the optimal motion vector is as follows.

If the encoding device omits the information indicating the optimal motion vector and transmits the size and sign of the difference between the optimal motion vector and the motion vector of the current block to the decoding device, the decoding device can confirm the difference through the size and sign of the difference, and add a candidate motion vector a that can be the optimal motion vector to the confirmed difference. At this time, if the derived value (which can be an estimated value of the motion vector coordinate value for the current block and therefore can be referred to as an estimated motion vector) is closer to a among a and b, it can be determined that the optimal motion vector is a. This is because if a is the optimal motion vector, the value derived by adding the candidate motion vector a to the difference value (k-a) becomes the motion vector (k) of the current block, and the encoding device would have selected the candidate motion vector a as the optimal motion vector because it is closest to the motion vector (k) of the current block.

In the same way, the decoding device can check the difference value through the size and sign of the difference value, and add a candidate motion vector b that can be the optimal motion vector to the checked difference value. At this time, if the derived value has a value closer to b among a and b, it can be determined that the optimal motion vector is b.

Meanwhile, as a result of performing the above processes for all candidate motion vectors, multiple motion vectors that can be the optimal motion vectors may be derived. In this case, since the decoding device cannot select a single optimal motion vector, the encoding device cannot omit information indicating the optimal motion vector. In other words, there may be cases where one optimal motion vector is not selected among the candidate motion vectors, and in such cases, the above method is not applied.

Here, the method of omitting information indicating the optimal motion vector was explained above based on the case where there are two candidate motion vectors, but since it would be easy for a person skilled in the art to understand that the same method can be applied even when there are multiple candidate motion vectors, a further detailed explanation is omitted.

Fig. 6 is a first example diagram showing an area where the motion vector of the current block can exist when there are three candidate motion vectors. Fig. 7 is a second example diagram showing an area where the motion vector of the current block can exist when there are three candidate motion vectors.

Referring to FIGS. 6 and 7, when there are three candidate motion vectors, a, b, and c (indicated based on the x or y coordinate in the drawings), the intervals between the candidate motion vectors (intervals between adjacent candidate motion vectors based on the x or y coordinate) can be between a and b, or between b and c.

At this time, the large interval between the candidate motion vectors can be defined as DL, and the small interval can be defined as DS. As shown in FIGS. 6 and 7, if the interval between candidate motion vectors a and b is a large interval, and the interval between candidate motion vectors b and c is a small interval, DL and DS are as shown in the following mathematical expressions 2 and 3.

In the relationship of the above mathematical expressions 2 and 3, it is assumed that the relationship between the difference between the motion vector of the current block and the optimal motion vector satisfies the following mathematical expression 4.

Under the conditions of the above mathematical expression 4, the area where the motion vector of the current block is located is illustrated in Fig. 6.

Referring to Fig. 6, if the candidate motion vector a is the optimal motion vector, the motion vector (k) of the current block is located within a distance greater than DS and less than or equal to DL with respect to a, and thus can be located in the first area (61a) and the second area (62a). That is, in this case, the difference value (k-a) can be either positive or negative.

In addition, if the candidate motion vector b is the optimal motion vector, the motion vector (k) of the current block is located within a distance greater than DS and less than or equal to DL with respect to b, and therefore can be located in the third region (61b). At this time, if the motion vector (k) of the current block is greater than b and has a value greater than DS with respect to b in the case where the candidate motion vector b is the optimal motion vector, the motion vector (k) of the current block may be closer to the candidate motion vector c than to the candidate motion vector b, and thus the precondition that the candidate motion vector b is the optimal motion vector may be violated. Accordingly, if the candidate motion vector b is the optimal motion vector, the motion vector (k) of the current block cannot be greater than b, and therefore, it can be seen that the difference value (k-b) is a negative number.

In addition, if the candidate motion vector c is the optimal motion vector, the motion vector (k) of the current block is located within a distance greater than DS and less than or equal to DL with respect to c, and thus can be located in the fourth region (62c). At this time, if the motion vector (k) of the current block is smaller than c and has a value smaller than DS with respect to c in the case where the candidate motion vector c is the optimal motion vector, the motion vector (k) of the current block may be closer to the candidate motion vector b than to the candidate motion vector c, and thus the precondition that the candidate motion vector c is the optimal motion vector may be violated. Therefore, if the candidate motion vector c is the optimal motion vector, the motion vector (k) of the current block cannot be smaller than c, and therefore, it can be seen that the difference value (k-c) is a positive number.

To summarize the description of FIG. 6, when the optimal motion vector is a, the motion vector (k) of the current block is located in the first area (61a) and the second area (62a), and the difference value (k-a) between the optimal motion vector (a) and the motion vector (k) of the current block in the first area (61a) is negative, and in the second area (62a) it is positive, so the difference value (k-a) can have both positive and negative numbers. Accordingly, when the optimal motion vector is a, the decoding device cannot know the sign of the difference value, so the encoding device can transmit the sign and size of the difference value (k-a) and information indicating the optimal motion vector to the decoding device.

However, if the optimal motion vector is b, the motion vector (k) of the current block is located in the third area (61b), so the decoding device can know that the sign of the differential value (k-b) is negative. In addition, if the optimal motion vector is c, the motion vector (k) of the current block is located in the fourth area (62c), so the decoding device can know that the sign of the differential value (k-c) is positive. Therefore, if the optimal motion vector is b or c, the encoding device can omit transmitting the sign of the differential value to the decoding device.

Meanwhile, let us assume that the relationship between the difference between the motion vector of the current block and the optimal motion vector in the relationship of the mathematical expressions 2 and 3 satisfies the following mathematical expression 5.

Under the conditions of the above mathematical expression 5, the area where the motion vector (k) of the current block is located is illustrated in Fig. 7.

Referring to FIG. 7, if the candidate motion vector a is the optimal motion vector, the motion vector (k) of the current block is located within a distance greater than DL from a, and thus can be located in the first region (71a). At this time, if the motion vector (k) of the current block is larger than a and located at a distance greater than DL from a in the case where the candidate motion vector a is the optimal motion vector, the motion vector (k) of the current block may be closer to the candidate motion vector b than to the candidate motion vector a, and thus the precondition that the candidate motion vector a is the optimal motion vector may be violated. Accordingly, if the candidate motion vector a is the optimal motion vector, the motion vector (k) of the current block cannot be larger than a, and therefore the difference value (k-a) may be negative.

In addition, if the candidate motion vector b is the optimal motion vector, the motion vector (k) of the current block must be located at a distance greater than DL from b. In this case, if the candidate motion vector b is the optimal motion vector and the motion vector (k) of the current block is located at a distance greater than DL from b, the motion vector (k) of the current block may be closer to the candidate motion vector a or c than to the candidate motion vector b, which may violate the precondition that the candidate motion vector b is the optimal motion vector. Accordingly, if the candidate motion vector is b, there is no area where the motion vector (k) of the current block exists, so the candidate motion vector cannot be b.

In addition, if the candidate motion vector c is the optimal motion vector, the motion vector (k) of the current block is located within a distance greater than DL from c, and thus can be located in the second region (72c). At this time, if the candidate motion vector c is the optimal motion vector and the motion vector (k) of the current block is smaller than c and is located at a distance greater than DL from c, the motion vector (k) of the current block may be closer to the candidate motion vector b than to the candidate motion vector c, and thus the precondition that the candidate motion vector c is the optimal motion vector may be violated. Accordingly, if the candidate motion vector c is the optimal motion vector, the motion vector (k) of the current block cannot be smaller than c, and therefore the difference value (k-c) can always be a positive number.

If we summarize the explanation of Fig. 7 based on the prerequisite of mathematical expression 5, when the optimal motion vector is a, the motion vector (k) of the current block is located in the first area (71a), and the differential value (k-a) between the optimal motion vector (a) and the motion vector (k) of the current block in the first area (71a) is negative. Therefore, when the optimal motion vector is a, the encoding device can omit transmitting the sign of the differential value to the decoding device.

In addition, when the optimal motion vector is b, the motion vector (k) of the current block does not exist in an area. Therefore, since the optimal motion vector cannot be b when satisfying Equation 5, the encoding device can exclude b from the candidate motion vector and define a or c as the candidate motion vector, generate information indicating the optimal motion vector among a and c, and transmit the information to the decoding device, and the decoding device can interpret a or c as the optimal motion vector through the information indicating the optimal motion vector by determining whether Equation 5 is satisfied. In this case, since one candidate motion vector is excluded, a bit value (1 bit) smaller than the bit value (2 bits) indicating one of the three can be used, which can increase the efficiency of encoding and decoding.

In addition, when the optimal motion vector is c, the motion vector (k) of the current block is located in the second area (72c), and the decoding device can know that the difference value (k-c) between the optimal motion vector (c) and the motion vector (k) of the current block in the second area (72c) is positive. Therefore, when the optimal motion vector is c, the encoding device can omit transmitting the sign of the difference value to the decoding device.

FIG. 8 is a flowchart of a video decoding method using inter-screen prediction according to one embodiment of the present invention.

Referring to FIG. 8, a method for decoding an image using inter-screen prediction may include a step of receiving a bitstream (S100), a step of obtaining a portion of information indicating a motion vector of a current block to be decoded from the received bitstream (S110), a step of obtaining a motion vector of the current block by determining the remaining information excluding the portion using the obtained information (S120), and a step of generating a prediction block of the current block through inter-screen prediction using the motion vector of the current block (S130).

Here, the information indicating the motion vector of the current block may include at least one of the size of the difference between the optimal motion vector selected from among two or more candidate motion vectors and the motion vector of the current block, the sign of the difference, and information indicating the optimal motion vector.

Here, the step (S120) of obtaining the motion vector of the current block may include a step of determining whether the size of the difference value corresponds to a preset condition, and if so, a step of determining the sign of the difference value based on the optimal motion vector obtained from information indicating the optimal motion vector.

Here, the preset condition may be set based on the interval between adjacent vectors among the two or more candidate motion vectors.

Here, the step of determining whether the size of the difference value corresponds to a preset condition may include the step of deriving a value having the largest interval between the adjacent vectors and a value having the smallest interval between the adjacent vectors, and the step of comparing the largest value and the smallest value with the size of the difference value.

Here, the preset condition can be set based on an interval that divides the interval between adjacent vectors in half.

Here, the step (S120) of obtaining the motion vector of the current block may include the step of obtaining the differential value using the magnitude of the differential value and the sign of the differential value, the step of determining an estimated motion vector of the current block by adding a first candidate motion vector among the two or more candidate motion vectors to the obtained differential value, the step of determining whether the estimated motion vector has a coordinate value that is closest to the first candidate motion vector among the two or more candidate motion vectors, and the step of determining the optimal motion vector based on the determination result.

Here, the step of determining the estimated motion vector and the step of judging can be repeatedly performed by substituting the remaining candidate motion vectors excluding the first candidate motion vector into the first candidate motion vector.

In this step of determining the optimal motion vector, if there is only one candidate motion vector having the closest coordinate value as a result of the iterative execution, the candidate motion vector can be determined as the optimal motion vector.

Here, the step (S120) of obtaining the motion vector of the current block may include the step of determining whether the size of the difference value corresponds to a preset condition, and if the preset condition corresponds, the step of excluding at least one motion vector among the two or more candidate motion vectors from the candidate motion vectors and determining the optimal motion vector among the remaining candidate motion vectors.

FIG. 9 is a configuration diagram of an image decoding device using inter-screen prediction according to one embodiment of the present invention.

Referring to FIG. 9, a video decoding device (200) using inter-screen prediction may include at least one processor (processor, 210) and a memory (memory, 220) that stores instructions that instruct the at least one processor (210) to perform at least one step.

Here, the image decoding device (200) may further include a communication module (230) that receives a bitstream from the image encoding device via a wired or wireless network.

Here, the image decoding device (200) may further include a local storage (240) that stores reference pictures, decoded blocks, etc. required for the image decoding process.

Here, at least one of the steps may include: receiving a bitstream; obtaining a portion of information indicating a motion vector of a current block to be decoded from the received bitstream; determining the remaining information excluding the portion by using the obtained information to obtain the motion vector of the current block; and generating a prediction block of the current block through inter-screen prediction using the motion vector of the current block.

Here, the information indicating the motion vector of the current block may include at least one of the size of the difference between the optimal motion vector selected from two or more candidate motion vectors and the motion vector of the current block, the sign of the difference, and information indicating the optimal motion vector.

Here, the step of obtaining the motion vector of the current block may include the step of determining whether the size of the difference value corresponds to a preset condition, and if the size corresponds to the preset condition, the step of determining the sign of the difference value based on the optimal motion vector obtained from the information indicating the optimal motion vector.

Here, the preset condition may be set based on the interval between adjacent vectors among the two or more candidate motion vectors.

Here, the step of determining whether the size of the difference value corresponds to a preset condition may include the step of deriving a value having the largest interval between the adjacent vectors and a value having the smallest interval between the adjacent vectors, and the step of comparing the largest value and the smallest value with the size of the difference value.

Here, the preset condition can be set based on an interval that divides the interval between adjacent vectors in half.

Here, the step of obtaining the motion vector of the current block may include the step of obtaining the differential value using the magnitude of the differential value and the sign of the differential value, the step of determining an estimated motion vector of the current block by adding a first candidate motion vector among the two or more candidate motion vectors to the obtained differential value, the step of determining whether the estimated motion vector has a coordinate value that is closest to the first candidate motion vector among the two or more candidate motion vectors, and the step of determining the optimal motion vector based on the determination result.

Here, the step of determining the estimated motion vector and the step of judging can be repeatedly performed by substituting the remaining candidate motion vectors excluding the first candidate motion vector into the first candidate motion vector.

In this step of determining the optimal motion vector, if there is only one candidate motion vector having the closest coordinate value as a result of the iterative execution, the candidate motion vector can be determined as the optimal motion vector.

Here, the step of obtaining the motion vector of the current block may include the step of determining whether the size of the difference value corresponds to a preset condition, and if the preset condition corresponds, the step of excluding at least one motion vector among the two or more candidate motion vectors from the candidate motion vectors and determining the optimal motion vector among the remaining candidate motion vectors.

Here, examples of the image decoding device (200) may include a desktop computer, a laptop computer, a notebook, a smart phone, a tablet PC, a mobile phone, a smart watch, a smart glass, an e-book reader, a portable multimedia player (PMP), a portable game console, a navigation device, a digital camera, a digital multimedia broadcasting (DMB) player, a digital audio recorder, a digital audio player, a digital video recorder, a digital video player, a PDA (Personal Digital Assistant), etc.

The methods according to the present invention may be implemented in the form of program commands that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program commands, data files, data structures, etc., alone or in combination. The program commands recorded on the computer-readable medium may be those specially designed and configured for the present invention or may be known and available to those skilled in the art of computer software.

Examples of computer-readable media may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions may include not only machine language codes generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, and the like. The above-described hardware devices may be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

In addition, the above-described method or device may be implemented by combining all or part of its configuration or function, or may be implemented separately.

Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims (8)

A video decoding method using inter-screen prediction.
Step of receiving a bitstream;
A step of determining a current block by dividing a coding block based on the division information included in the above bitstream;
A step of obtaining an estimated motion vector of the current block based on a plurality of candidate motion vectors and motion vector indication information, wherein the motion vector indication information indicates one of the plurality of candidate motion vectors;
A step of obtaining the motion vector differential of the current block based on the size information of the motion vector differential and the sign information of the motion vector differential;
A step of obtaining a motion vector of the current block by using the estimated motion vector and the motion vector difference; and
A step of generating a prediction block of the current block through inter-screen prediction using the motion vector of the current block,
Whether or not the above code information is signaled is determined based on whether the size of the motion vector difference value is greater than a pre-defined threshold size.
If the size of the above motion vector difference is greater than a pre-defined threshold size, the sign information is signaled,
If the size of the above motion vector difference is less than or equal to a pre-defined threshold size, the sign information is not signaled.
Based on the residual block of the current block obtained based on the scan pattern from the predicted block and the bitstream, the current block is decoded,
An image decoding method, characterized in that the scan pattern is a zigzag scan pattern, a diagonal scan pattern, or a raster scan pattern. In the first paragraph,
A method for decoding an image, wherein the above-described splitting information includes at least one of a quad tree splitting flag indicating whether to split based on a quad tree splitting, a binary tree splitting flag indicating whether to split based on a binary tree splitting, or a splitting direction flag indicating whether to split in a vertical direction or a horizontal direction. In the second paragraph,
A method for decoding an image, wherein the coding block is divided based on a division type including at least one of the quad tree division or the binary tree division. In the third paragraph,
An image decoding method in which only the quad tree division is used to divide the coding block when the coding block has a size of 128x128. In the third paragraph,
A method for decoding an image, wherein the above binary tree partitioning is allowed only if block partitioning based on the above quad tree partitioning is no longer performed. In the second paragraph,
The above split direction flag is optionally signaled depending on the split type of the upper block to which the above coding block belongs.
A method for decoding an image, wherein the upper block represents a block having a smaller split depth than the coding block. A video encoding method using inter-screen prediction.
A step of encoding division information for dividing a first coding block into a plurality of second coding blocks;
A step for encoding a motion vector for inter-screen prediction of the current block;
Here, the current block is one of the second coding blocks,
The step of encoding the motion vector of the current block is:
A step of encoding motion vector indication information indicating an estimated motion vector of the current block among a plurality of candidate motion vectors, and
A step of encoding size information for determining the size of the motion vector differential value of the current block and sign information for determining the sign of the motion vector differential value; and
Comprising a step of generating a bitstream including the above segmentation information, the motion vector indication information, the size information and the sign information,
Whether or not the above-mentioned sign information is encoded is determined based on whether the size of the motion vector difference value is greater than a pre-defined threshold size.
If the size of the above motion vector difference is greater than a pre-defined threshold size, the sign information is encoded,
If the size of the above motion vector difference is less than or equal to a pre-defined threshold size, the sign information is not encoded.
Based on the original block of the current block and the predicted block of the current block, the residual block of the current block is encoded based on the scan pattern,
The prediction block of the current block is obtained through inter-screen prediction of the current block,
An image encoding method, characterized in that the scan pattern is a zigzag scan pattern, a diagonal scan pattern, or a raster scan pattern. A computer-readable recording medium storing a bitstream generated by a video encoding method using inter-screen prediction,
The above image encoding method is,
A step of encoding division information for dividing a first coding block into a plurality of second coding blocks;
A step for encoding a motion vector for inter-screen prediction of the current block;
Here, the current block is one of the second coding blocks,
The step of encoding the motion vector of the current block is:
A step of encoding motion vector indication information indicating an estimated motion vector of the current block among a plurality of candidate motion vectors, and
A step of encoding size information for determining the size of the motion vector differential value of the current block and sign information for determining the sign of the motion vector differential value; and
A step of generating the bitstream including the above segmentation information, the motion vector indication information, the size information and the sign information,
Whether or not the above-mentioned sign information is encoded is determined based on whether the size of the motion vector difference value is greater than a pre-defined threshold size.
If the size of the above motion vector difference is greater than a pre-defined threshold size, the sign information is encoded,
If the size of the above motion vector difference is less than or equal to a pre-defined threshold size, the sign information is not encoded.
Based on the original block of the current block and the predicted block of the current block, the residual block of the current block is encoded based on the scan pattern,
The prediction block of the current block is obtained through inter-screen prediction of the current block,
A computer-readable recording medium, characterized in that the scan pattern is a zigzag scan pattern, a diagonal scan pattern, or a raster scan pattern.