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WO2018169099A1 - Procédé de traitement d'image basée sur un mode d'inter-prédiction et dispositif associé - Google Patents

Procédé de traitement d'image basée sur un mode d'inter-prédiction et dispositif associé Download PDF

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Publication number
WO2018169099A1
WO2018169099A1 PCT/KR2017/002693 KR2017002693W WO2018169099A1 WO 2018169099 A1 WO2018169099 A1 WO 2018169099A1 KR 2017002693 W KR2017002693 W KR 2017002693W WO 2018169099 A1 WO2018169099 A1 WO 2018169099A1
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gradient
pixel
value
complexity
current
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PCT/KR2017/002693
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English (en)
Korean (ko)
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이재호
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엘지전자(주)
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
    • H04N19/51—Motion estimation or motion compensation
    • H04N19/513—Processing of motion vectors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
    • H04N19/51—Motion estimation or motion compensation
    • H04N19/57—Motion estimation characterised by a search window with variable size or shape
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
    • H04N19/51—Motion estimation or motion compensation
    • H04N19/573—Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction

Definitions

  • the present invention relates to a still image or moving image processing method, and more particularly, to a method for encoding / decoding a still image or moving image based on an inter prediction mode and an apparatus supporting the same.
  • Compression coding refers to a series of signal processing techniques for transmitting digitized information through a communication line or for storing in a form suitable for a storage medium.
  • Media such as an image, an image, an audio, and the like may be a target of compression encoding.
  • a technique of performing compression encoding on an image is called video image compression.
  • Next-generation video content will be characterized by high spatial resolution, high frame rate and high dimensionality of scene representation. Processing such content would result in a tremendous increase in terms of memory storage, memory access rate, and processing power.
  • the existing Bi-directional Optical Flow (BIO) method is performed when the gradient component in the horizontal direction and the vertical direction exceeds the threshold in pixels.
  • BIO Bi-directional Optical Flow
  • an object of the present invention is to propose a method of selectively using a bidirectional prediction value generated through bidirectional prediction and a prediction value generated by applying a BIO method.
  • a bidirectional prediction value (Bi ⁇ ) of a current pixel in the current block is performed by performing bidirectional inter prediction based on a motion vector of a current block.
  • generating a directional predictor The region of the specific size by using a gradient representing a change amount of a pixel value in a horizontal direction or a vertical direction with respect to each pixel in the region of a specific size of the first reference picture and the second reference picture of the current block Calculating a gradient complexity indicative of the degree of complexity in the motion; When the gradient complexity is less than a certain threshold, a first window area centered on a pixel that is collocated with the current pixel in the first and second reference blocks of the current block; Deriving a motion vector in units of pixels of the current pixel using a gradient within the gradient; And generating a predictor of the current pixel by adjusting the bidirectional predictive value based on the motion vector of the pixel unit.
  • a bidirectional prediction value Bi of a current pixel in the current block is performed by performing bidirectional inter prediction based on a motion vector of a current block.
  • a bidirectional predictor generating unit generating a directional predictor; The region of the specific size by using a gradient representing a change amount of a pixel value in a horizontal direction or a vertical direction with respect to each pixel in the region of a specific size of the first reference picture and the second reference picture of the current block
  • Gradient complexity calculation unit for calculating a gradient complexity (gradient complexity) representing the complexity of the motion (motion); When the gradient complexity is less than a certain threshold, a first window area centered on a pixel that is collocated with the current pixel in the first and second reference blocks of the current block;
  • a pixel-by-pixel motion vector derivation unit that derives a motion vector of a pixel unit of the current pixel by using a gradient within the pixel;
  • the bidirectional prediction value may be determined as the prediction value of the current pixel.
  • the specific size region may be the first window region.
  • the gradient complexity may be calculated using the gradient value of each pixel in the first window area.
  • the gradient complexity may be calculated using the sum of squares of the horizontal components of the gradient and the sum of the vertical components of the gradient in the first window area.
  • the gradient complexity may be calculated using a difference value between a gradient value of a pixel having the same coordinates as the current pixel and a gradient value of each pixel in the first window area.
  • the gradient complexity may be calculated using a sign of a difference value between a gradient value of a pixel having the same coordinate as the current pixel and a gradient value of each pixel in the first window area.
  • the specific size region may be a second window region including the first reference block and the second reference block.
  • the specific size area is an area of size (W + 4) ⁇ (H + 4) including the first reference block and the second reference block when the size of the current block is W ⁇ H. Can be.
  • the gradient complexity may be calculated using the gradient value of each pixel in the second window area.
  • the gradient complexity may be calculated using the sum of squares of the horizontal components and the sum of the vertical components of the gradient in the second window area.
  • the gradient complexity may be calculated using a difference value of a gradient value of each pixel in the second window area and a gradient value of a pixel adjacent to each pixel.
  • the gradient complexity may be calculated using a difference value between a gradient value of each pixel in the second window area and an average value of the gradient in the second window area.
  • encoding efficiency may be improved by selectively using a bidirectional prediction value generated through bidirectional prediction and a prediction value in units of pixels based on an optical flow.
  • FIG. 1 is a schematic block diagram of an encoder in which encoding of a still image or video signal is performed according to an embodiment to which the present invention is applied.
  • FIG. 2 is a schematic block diagram of a decoder in which encoding of a still image or video signal is performed according to an embodiment to which the present invention is applied.
  • FIG. 3 is a diagram for describing a partition structure of a coding unit that may be applied to the present invention.
  • FIG. 4 is a diagram for explaining a prediction unit applicable to the present invention.
  • FIG. 5 is a diagram illustrating a direction of inter prediction as an embodiment to which the present invention may be applied.
  • FIG 6 illustrates integer and fractional sample positions for quarter sample interpolation, as an embodiment to which the present invention may be applied.
  • FIG. 7 illustrates a position of a spatial candidate as an embodiment to which the present invention may be applied.
  • FIG. 8 is a diagram illustrating an inter prediction method as an embodiment to which the present invention is applied.
  • FIG. 9 is a diagram illustrating a motion compensation process as an embodiment to which the present invention may be applied.
  • FIG. 10 illustrates, as an embodiment to which the present invention may be applied, a bidirectional prediction method of a picture having a steady motion.
  • FIG. 11 is a diagram illustrating a motion compensation method through bidirectional prediction according to an embodiment of the present invention.
  • FIG. 12 is a diagram illustrating a method of determining a gradient map according to an embodiment of the present invention.
  • FIG. 13 is a diagram illustrating a method of determining an optical flow motion vector according to an embodiment of the present invention.
  • FIG. 14 is a diagram for describing a motion compensation method in units of pixels as an embodiment to which the present invention can be applied.
  • 15 is a diagram illustrating a method of determining an optical flow motion vector according to an embodiment of the present invention.
  • 16 is a diagram illustrating a motion compensation method through bidirectional prediction according to an embodiment of the present invention.
  • 17 is a diagram illustrating an inter prediction based image processing method according to an embodiment of the present invention.
  • FIG. 18 is a diagram illustrating an inter predictor according to an embodiment of the present invention.
  • the 'processing unit' refers to a unit in which a process of encoding / decoding such as prediction, transformation, and / or quantization is performed.
  • the processing unit may be referred to as a 'processing block' or 'block'.
  • the processing unit may be interpreted to include a unit for the luma component and a unit for the chroma component.
  • the processing unit may correspond to a Coding Tree Unit (CTU), a Coding Unit (CU), a Prediction Unit (PU), or a Transform Unit (TU).
  • CTU Coding Tree Unit
  • CU Coding Unit
  • PU Prediction Unit
  • TU Transform Unit
  • the processing unit may be interpreted as a unit for a luma component or a unit for a chroma component.
  • the processing unit may be a coding tree block (CTB), a coding block (CB), a prediction block (PU), or a transform block (TB) for a luma component. May correspond to. Or, it may correspond to a coding tree block (CTB), a coding block (CB), a prediction block (PU), or a transform block (TB) for a chroma component.
  • CTB coding tree block
  • CB coding block
  • PU prediction block
  • TB transform block
  • the present invention is not limited thereto, and the processing unit may be interpreted to include a unit for a luma component and a unit for a chroma component.
  • processing unit is not necessarily limited to square blocks, but may also be configured in a polygonal form having three or more vertices.
  • FIG. 1 is a schematic block diagram of an encoder in which encoding of a still image or video signal is performed according to an embodiment to which the present invention is applied.
  • the encoder 100 may include an image divider 110, a subtractor 115, a transform unit 120, a quantizer 130, an inverse quantizer 140, an inverse transform unit 150, and a filtering unit. 160, a decoded picture buffer (DPB) 170, a predictor 180, and an entropy encoder 190.
  • the predictor 180 may include an inter predictor 181 and an intra predictor 182.
  • the image divider 110 divides an input video signal (or a picture or a frame) input to the encoder 100 into one or more processing units.
  • the subtractor 115 subtracts the difference from the prediction signal (or prediction block) output from the prediction unit 180 (that is, the inter prediction unit 181 or the intra prediction unit 182) in the input image signal. Generate a residual signal (or difference block). The generated difference signal (or difference block) is transmitted to the converter 120.
  • the transform unit 120 may convert a differential signal (or a differential block) into a transform scheme (eg, a discrete cosine transform (DCT), a discrete sine transform (DST), a graph-based transform (GBT), and a karhunen-loeve transform (KLT)). Etc.) to generate transform coefficients.
  • a transform scheme eg, a discrete cosine transform (DCT), a discrete sine transform (DST), a graph-based transform (GBT), and a karhunen-loeve transform (KLT)
  • the quantization unit 130 quantizes the transform coefficients and transmits the transform coefficients to the entropy encoding unit 190, and the entropy encoding unit 190 entropy codes the quantized signals and outputs them as bit streams.
  • the quantized signal output from the quantization unit 130 may be used to generate a prediction signal.
  • the quantized signal may recover the differential signal by applying inverse quantization and inverse transformation through an inverse quantization unit 140 and an inverse transformation unit 150 in a loop.
  • a reconstructed signal may be generated by adding the reconstructed difference signal to a prediction signal output from the inter predictor 181 or the intra predictor 182.
  • the filtering unit 160 applies filtering to the reconstruction signal and outputs it to the reproduction apparatus or transmits the decoded picture buffer to the decoding picture buffer 170.
  • the filtered signal transmitted to the decoded picture buffer 170 may be used as the reference picture in the inter prediction unit 181. As such, by using the filtered picture as a reference picture in the inter prediction mode, not only image quality but also encoding efficiency may be improved.
  • the decoded picture buffer 170 may store the filtered picture for use as a reference picture in the inter prediction unit 181.
  • the inter prediction unit 181 performs temporal prediction and / or spatial prediction to remove temporal redundancy and / or spatial redundancy with reference to a reconstructed picture.
  • the reference picture used to perform the prediction is a transformed signal that has been quantized and dequantized in units of blocks at the time of encoding / decoding, a blocking artifact or a ringing artifact may exist. have.
  • the inter prediction unit 181 may interpolate the signals between pixels in sub-pixel units by applying a lowpass filter to solve performance degradation due to discontinuity or quantization of such signals.
  • the sub-pixel refers to a virtual pixel generated by applying an interpolation filter
  • the integer pixel refers to an actual pixel existing in the reconstructed picture.
  • the interpolation method linear interpolation, bi-linear interpolation, wiener filter, or the like may be applied.
  • the interpolation filter may be applied to a reconstructed picture to improve the precision of prediction.
  • the inter prediction unit 181 generates an interpolation pixel by applying an interpolation filter to integer pixels, and uses an interpolated block composed of interpolated pixels as a prediction block. You can make predictions.
  • the intra predictor 182 predicts the current block by referring to samples in the vicinity of the block to which the current encoding is to be performed.
  • the intra prediction unit 182 may perform the following process to perform intra prediction. First, reference samples necessary for generating a prediction signal may be prepared. The prediction signal may be generated using the prepared reference sample. Then, the prediction mode is encoded. In this case, the reference sample may be prepared through reference sample padding and / or reference sample filtering. Since the reference sample has been predicted and reconstructed, there may be a quantization error. Accordingly, the reference sample filtering process may be performed for each prediction mode used for intra prediction to reduce such an error.
  • the prediction signal (or prediction block) generated by the inter prediction unit 181 or the intra prediction unit 182 is used to generate a reconstruction signal (or reconstruction block) or a differential signal (or differential block). It can be used to generate.
  • FIG. 2 is a schematic block diagram of a decoder in which encoding of a still image or video signal is performed according to an embodiment to which the present invention is applied.
  • the decoder 200 includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an adder 235, a filtering unit 240, and a decoded picture buffer (DPB).
  • Buffer Unit (250) the prediction unit 260 may be configured.
  • the predictor 260 may include an inter predictor 261 and an intra predictor 262.
  • the reconstructed video signal output through the decoder 200 may be reproduced through the reproducing apparatus.
  • the decoder 200 receives a signal (ie, a bit stream) output from the encoder 100 of FIG. 1, and the received signal is entropy decoded through the entropy decoding unit 210.
  • the inverse quantization unit 220 obtains a transform coefficient from the entropy decoded signal using the quantization step size information.
  • the inverse transform unit 230 applies an inverse transform scheme to inverse transform the transform coefficients to obtain a residual signal (or a differential block).
  • the adder 235 outputs the obtained difference signal (or difference block) from the prediction unit 260 (that is, the prediction signal (or prediction block) output from the inter prediction unit 261 or the intra prediction unit 262. ) Generates a reconstructed signal (or a reconstruction block).
  • the filtering unit 240 applies filtering to the reconstructed signal (or the reconstructed block) and outputs the filtering to the reproduction device or transmits the decoded picture buffer unit 250 to the reproduction device.
  • the filtered signal transmitted to the decoded picture buffer unit 250 may be used as a reference picture in the inter predictor 261.
  • the embodiments described by the filtering unit 160, the inter prediction unit 181, and the intra prediction unit 182 of the encoder 100 are respectively the filtering unit 240, the inter prediction unit 261, and the decoder of the decoder. The same may be applied to the intra predictor 262.
  • a still image or video compression technique uses a block-based image compression method.
  • the block-based image compression method is a method of processing an image by dividing the image into specific block units, and may reduce memory usage and calculation amount.
  • FIG. 3 is a diagram for describing a partition structure of a coding unit that may be applied to the present invention.
  • the encoder splits one image (or picture) into units of a coding tree unit (CTU) in a rectangular shape.
  • CTU coding tree unit
  • one CTU is sequentially encoded according to a raster scan order.
  • the size of the CTU may be set to any one of 64 ⁇ 64, 32 ⁇ 32, and 16 ⁇ 16.
  • the encoder may select and use the size of the CTU according to the resolution of the input video or the characteristics of the input video.
  • the CTU includes a coding tree block (CTB) for luma components and a CTB for two chroma components corresponding thereto.
  • CTB coding tree block
  • One CTU may be divided into a quad-tree structure. That is, one CTU has a square shape and is divided into four units having a half horizontal size and a half vertical size to generate a coding unit (CU). have. This partitioning of the quad-tree structure can be performed recursively. That is, a CU is hierarchically divided into quad-tree structures from one CTU.
  • CU coding unit
  • the CU refers to a basic unit of coding in which an input image is processed, for example, intra / inter prediction is performed.
  • the CU includes a coding block (CB) for a luma component and a CB for two chroma components corresponding thereto.
  • CB coding block
  • the size of a CU may be set to any one of 64 ⁇ 64, 32 ⁇ 32, 16 ⁇ 16, and 8 ⁇ 8.
  • the root node of the quad-tree is associated with the CTU.
  • the quad-tree is split until it reaches a leaf node, which corresponds to a CU.
  • the CTU may not be divided according to the characteristics of the input image.
  • the CTU corresponds to a CU.
  • a node that is no longer divided ie, a leaf node
  • CU a node that is no longer divided
  • CU a node that is no longer divided
  • CU a node corresponding to nodes a, b, and j are divided once in the CTU and have a depth of one.
  • a node (ie, a leaf node) that is no longer divided in a lower node having a depth of 2 corresponds to a CU.
  • CU (c), CU (h) and CU (i) corresponding to nodes c, h and i are divided twice in the CTU and have a depth of two.
  • a node that is no longer partitioned (ie, a leaf node) in a lower node having a depth of 3 corresponds to a CU.
  • CU (d), CU (e), CU (f), and CU (g) corresponding to nodes d, e, f, and g are divided three times in the CTU, Has depth.
  • the maximum size or the minimum size of the CU may be determined according to characteristics (eg, resolution) of the video image or in consideration of encoding efficiency. Information about this or information capable of deriving the information may be included in the bitstream.
  • a CU having a maximum size may be referred to as a largest coding unit (LCU), and a CU having a minimum size may be referred to as a smallest coding unit (SCU).
  • LCU largest coding unit
  • SCU smallest coding unit
  • a CU having a tree structure may be hierarchically divided with predetermined maximum depth information (or maximum level information).
  • Each partitioned CU may have depth information. Since the depth information indicates the number and / or degree of division of the CU, the depth information may include information about the size of the CU.
  • the size of the SCU can be obtained by using the size and maximum depth information of the LCU. Or conversely, using the size of the SCU and the maximum depth information of the tree, the size of the LCU can be obtained.
  • information indicating whether the corresponding CU is split may be transmitted to the decoder.
  • This split mode is included in all CUs except the SCU. For example, if the flag indicating whether to split or not is '1', the CU is divided into 4 CUs again. If the flag indicating whether to split or not is '0', the CU is not divided further. Processing may be performed.
  • a CU is a basic unit of coding in which intra prediction or inter prediction is performed.
  • HEVC divides a CU into prediction units (PUs) in order to code an input image more effectively.
  • the PU is a basic unit for generating a prediction block, and may generate different prediction blocks in PU units within one CU. However, PUs belonging to one CU are not mixed with intra prediction and inter prediction, and PUs belonging to one CU are coded by the same prediction method (ie, intra prediction or inter prediction).
  • the PU is not divided into quad-tree structures, but is divided once in a predetermined form in one CU. This will be described with reference to the drawings below.
  • FIG. 4 is a diagram for explaining a prediction unit applicable to the present invention.
  • the PU is divided differently according to whether an intra prediction mode or an inter prediction mode is used as a coding mode of a CU to which the PU belongs.
  • FIG. 4A illustrates a PU when an intra prediction mode is used
  • FIG. 4B illustrates a PU when an inter prediction mode is used.
  • N ⁇ N type PU when divided into N ⁇ N type PU, one CU is divided into four PUs, and different prediction blocks are generated for each PU unit.
  • the division of the PU may be performed only when the size of the CB for the luminance component of the CU is the minimum size (that is, the CU is the SCU).
  • one CU has 8 PU types (ie, 2N ⁇ 2N). , N ⁇ N, 2N ⁇ N, N ⁇ 2N, nL ⁇ 2N, nR ⁇ 2N, 2N ⁇ nU, 2N ⁇ nD).
  • PU partitioning in the form of N ⁇ N may be performed only when the size of the CB for the luminance component of the CU is the minimum size (that is, the CU is the SCU).
  • AMP Asymmetric Motion Partition
  • 'n' means a 1/4 value of 2N.
  • AMP cannot be used when the CU to which the PU belongs is a CU of the minimum size.
  • an optimal partitioning structure of a coding unit (CU), a prediction unit (PU), and a transformation unit (TU) is subjected to the following process to perform a minimum rate-distortion. It can be determined based on the value. For example, looking at the optimal CU partitioning process in 64 ⁇ 64 CTU, rate-distortion cost can be calculated while partitioning from a 64 ⁇ 64 CU to an 8 ⁇ 8 CU.
  • the specific process is as follows.
  • the partition structure of the optimal PU and TU that generates the minimum rate-distortion value is determined by performing inter / intra prediction, transform / quantization, inverse quantization / inverse transform, and entropy encoding for a 64 ⁇ 64 CU.
  • the 32 ⁇ 32 CU is subdivided into four 16 ⁇ 16 CUs, and a partition structure of an optimal PU and TU that generates a minimum rate-distortion value for each 16 ⁇ 16 CU is determined.
  • 16 ⁇ 16 blocks by comparing the sum of the rate-distortion values of the 16 ⁇ 16 CUs calculated in 3) above with the rate-distortion values of the four 8 ⁇ 8 CUs calculated in 4) above. Determine the partition structure of the optimal CU within. This process is similarly performed for the remaining three 16 ⁇ 16 CUs.
  • a prediction mode is selected in units of PUs, and prediction and reconstruction are performed in units of actual TUs for the selected prediction mode.
  • the TU means a basic unit in which actual prediction and reconstruction are performed.
  • the TU includes a transform block (TB) for a luma component and a TB for two chroma components corresponding thereto.
  • TB transform block
  • the TUs are hierarchically divided into quad-tree structures from one CU to be coded.
  • the TU divided from the CU can be further divided into smaller lower TUs.
  • the size of the TU may be set to any one of 32 ⁇ 32, 16 ⁇ 16, 8 ⁇ 8, and 4 ⁇ 4.
  • a root node of the quad-tree is associated with a CU.
  • the quad-tree is split until it reaches a leaf node, which corresponds to a TU.
  • the CU may not be divided according to the characteristics of the input image.
  • the CU corresponds to a TU.
  • a node ie, a leaf node
  • TU (a), TU (b), and TU (j) corresponding to nodes a, b, and j are divided once in a CU and have a depth of 1.
  • FIG. 3B TU (a), TU (b), and TU (j) corresponding to nodes a, b, and j are divided once in a CU and have a depth of 1.
  • a node (ie, a leaf node) that is no longer divided in a lower node having a depth of 2 corresponds to a TU.
  • TU (c), TU (h), and TU (i) corresponding to nodes c, h, and i are divided twice in a CU and have a depth of two.
  • a node that is no longer partitioned (ie, a leaf node) in a lower node having a depth of 3 corresponds to a CU.
  • TU (d), TU (e), TU (f), and TU (g) corresponding to nodes d, e, f, and g are divided three times in a CU. Has depth.
  • a TU having a tree structure may be hierarchically divided with predetermined maximum depth information (or maximum level information). Each divided TU may have depth information. Since the depth information indicates the number and / or degree of division of the TU, it may include information about the size of the TU.
  • information indicating whether the corresponding TU is split may be delivered to the decoder.
  • This partitioning information is included in all TUs except the smallest TU. For example, if the value of the flag indicating whether to split is '1', the corresponding TU is divided into four TUs again. If the value of the flag indicating whether to split is '0', the corresponding TU is no longer divided.
  • the decoded portion of the current picture or other pictures in which the current processing unit is included may be used to reconstruct the current processing unit in which decoding is performed.
  • Intra picture or I picture which uses only the current picture for reconstruction, i.e. performs only intra picture prediction, predicts a picture (slice) using at most one motion vector and reference index to predict each unit
  • a picture using a predictive picture or P picture (slice), up to two motion vectors, and a reference index (slice) may be referred to as a bi-predictive picture or a B picture (slice).
  • Intra prediction means a prediction method that derives the current processing block from data elements (eg, sample values, etc.) of the same decoded picture (or slice). That is, a method of predicting pixel values of the current processing block by referring to reconstructed regions in the current picture.
  • data elements eg, sample values, etc.
  • Inter Inter prediction (or inter screen prediction)
  • Inter prediction means a prediction method of deriving a current processing block based on data elements (eg, sample values or motion vectors, etc.) of pictures other than the current picture. That is, a method of predicting pixel values of the current processing block by referring to reconstructed regions in other reconstructed pictures other than the current picture.
  • data elements eg, sample values or motion vectors, etc.
  • Inter prediction (or inter picture prediction) is a technique for removing redundancy existing between pictures, and is mostly performed through motion estimation and motion compensation.
  • FIG. 5 is a diagram illustrating a direction of inter prediction as an embodiment to which the present invention may be applied.
  • inter prediction includes uni-directional prediction that uses only one past picture or a future picture as a reference picture on a time axis with respect to one block, and bidirectional prediction that simultaneously refers to past and future pictures. Bi-directional prediction).
  • uni-directional prediction includes forward direction prediction using one reference picture displayed (or output) before the current picture in time and 1 displayed (or output) after the current picture in time. It can be divided into backward direction prediction using two reference pictures.
  • the motion parameter (or information) used to specify which reference region (or reference block) is used to predict the current block in the inter prediction process is an inter prediction mode (where
  • the inter prediction mode may indicate a reference direction (i.e., unidirectional or bidirectional) and a reference list (i.e., L0, L1 or bidirectional), a reference index (or reference picture index or reference list index), Contains motion vector information.
  • the motion vector information may include a motion vector, a motion vector prediction (MVP), or a motion vector difference (MVD).
  • the motion vector difference value means a difference value between the motion vector and the motion vector prediction value.
  • motion parameters for one direction are used. That is, one motion parameter may be needed to specify the reference region (or reference block).
  • Bidirectional prediction uses motion parameters for both directions.
  • up to two reference regions may be used.
  • the two reference regions may exist in the same reference picture or may exist in different pictures, respectively. That is, up to two motion parameters may be used in the bidirectional prediction scheme, and two motion vectors may have the same reference picture index or different reference picture indexes. In this case, all of the reference pictures may be displayed (or output) before or after the current picture in time.
  • the encoder performs motion estimation to find the reference region most similar to the current processing block from the reference pictures in the inter prediction process.
  • the encoder may provide a decoder with a motion parameter for the reference region.
  • the encoder / decoder may obtain a reference region of the current processing block using the motion parameter.
  • the reference region exists in a reference picture having the reference index.
  • the pixel value or interpolated value of the reference region specified by the motion vector may be used as a predictor of the current processing block. That is, using motion information, motion compensation is performed to predict an image of a current processing block from a previously decoded picture.
  • a method of acquiring a motion vector prediction value mvp using motion information of previously coded blocks and transmitting only a difference value mvd thereof may be used. That is, the decoder obtains a motion vector prediction value of the current processing block using motion information of other decoded blocks, and obtains a motion vector value for the current processing block using the difference value transmitted from the encoder. In obtaining the motion vector prediction value, the decoder may obtain various motion vector candidate values by using motion information of other blocks that are already decoded, and obtain one of them as the motion vector prediction value.
  • a set of previously decoded pictures are stored in a decoded picture buffer (DPB) for decoding the remaining pictures.
  • DPB decoded picture buffer
  • a reference picture refers to a picture including a sample that can be used for inter prediction in a decoding process of a next picture in decoding order.
  • a reference picture set refers to a set of reference pictures associated with a picture, and is composed of all pictures previously associated in decoding order.
  • the reference picture set may be used for inter prediction of an associated picture or a picture following an associated picture in decoding order. That is, reference pictures maintained in the decoded picture buffer DPB may be referred to as a reference picture set.
  • the encoder may provide the decoder with reference picture set information in a sequence parameter set (SPS) (ie, a syntax structure composed of syntax elements) or each slice header.
  • SPS sequence parameter set
  • a reference picture list refers to a list of reference pictures used for inter prediction of a P picture (or slice) or a B picture (or slice).
  • the reference picture list may be divided into two reference picture lists, and may be referred to as reference picture list 0 (or L0) and reference picture list 1 (or L1), respectively.
  • a reference picture belonging to reference picture list 0 may be referred to as reference picture 0 (or L0 reference picture)
  • a reference picture belonging to reference picture list 1 may be referred to as reference picture 1 (or L1 reference picture).
  • one reference picture list i.e., reference picture list 0
  • two reference picture lists i.e., reference Picture list 0 and reference picture list 1
  • Such information for distinguishing a reference picture list for each reference picture may be provided to the decoder through reference picture set information.
  • the decoder adds the reference picture to the reference picture list 0 or the reference picture list 1 based on the reference picture set information.
  • a reference picture index (or reference index) is used to identify any one specific reference picture in the reference picture list.
  • a sample of the prediction block for the inter predicted current processing block is obtained from the sample value of the corresponding reference region in the reference picture identified by the reference picture index.
  • the corresponding reference region in the reference picture represents the region of the position indicated by the horizontal component and the vertical component of the motion vector.
  • Fractional sample interpolation is used to generate predictive samples for noninteger sample coordinates, except when the motion vector has an integer value. For example, a motion vector of one quarter of the distance between samples may be supported.
  • fractional sample interpolation of luminance components applies an 8-tap filter in the horizontal and vertical directions, respectively.
  • fractional sample interpolation of the color difference component applies a 4-tap filter in the horizontal direction and the vertical direction, respectively.
  • FIG 6 illustrates integer and fractional sample positions for quarter sample interpolation, as an embodiment to which the present invention may be applied.
  • the shaded block in which the upper-case letter (A_i, j) is written indicates the integer sample position
  • the shaded block in which the lower-case letter (x_i, j) is written is the fractional sample position. Indicates.
  • Fractional samples are generated by applying interpolation filters to integer sample values in the horizontal and vertical directions, respectively.
  • an 8-tap filter may be applied to four integer sample values on the left side and four integer sample values on the right side based on the fractional sample to be generated.
  • a merge mode and advanced motion vector prediction may be used to reduce the amount of motion information.
  • Merge mode refers to a method of deriving a motion parameter (or information) from a neighboring block spatially or temporally.
  • the set of candidates available in merge mode is composed of spatial neighbor candidates, temporal candidates and generated candidates.
  • FIG. 7 illustrates a position of a spatial candidate as an embodiment to which the present invention may be applied.
  • each spatial candidate block is available according to the order of ⁇ A1, B1, B0, A0, B2 ⁇ . In this case, when the candidate block is encoded in the intra prediction mode and there is no motion information, or when the candidate block is located outside the current picture (or slice), the candidate block is not available.
  • the spatial merge candidate can be constructed by excluding unnecessary candidate blocks from candidate blocks of the current processing block. For example, when the candidate block of the current prediction block is the first prediction block in the same coding block, the candidate block having the same motion information may be excluded except for the corresponding candidate block.
  • the temporal merge candidate configuration process is performed in the order of ⁇ T0, T1 ⁇ .
  • the block when the right bottom block T0 of the collocated block of the reference picture is available, the block is configured as a temporal merge candidate.
  • the colocated block refers to a block existing at a position corresponding to the current processing block in the selected reference picture.
  • the block T1 located at the center of the collocated block is configured as a temporal merge candidate.
  • the maximum number of merge candidates may be specified in the slice header. If the number of merge candidates is larger than the maximum number, the number of spatial candidates and temporal candidates smaller than the maximum number is maintained. Otherwise, the number of merge candidates is generated by combining the candidates added so far until the maximum number of candidates becomes the maximum (ie, combined bi-predictive merging candidates). .
  • the encoder constructs a merge candidate list in the above manner and performs motion estimation to merge candidate block information selected from the merge candidate list into a merge index (for example, merge_idx [x0] [y0] '). Signal to the decoder.
  • a merge index for example, merge_idx [x0] [y0] '.
  • the B1 block is selected from the merge candidate list.
  • “index 1” may be signaled to the decoder as a merge index.
  • the decoder constructs a merge candidate list similarly to the encoder, and derives the motion information of the current block from the motion information of the candidate block corresponding to the merge index received from the encoder in the merge candidate list.
  • the decoder generates a prediction block for the current processing block based on the derived motion information (ie, motion compensation).
  • the AMVP mode refers to a method of deriving a motion vector prediction value from neighboring blocks.
  • horizontal and vertical motion vector difference (MVD), reference index, and inter prediction modes are signaled to the decoder.
  • the horizontal and vertical motion vector values are calculated using the derived motion vector prediction value and the motion vector difference (MVD) provided from the encoder.
  • the encoder constructs a motion vector predictor candidate list and performs motion estimation to perform a motion estimation flag (ie, candidate block information) selected from the motion vector predictor candidate list (for example, mvp_lX_flag [x0] [y0). ] ') Is signaled to the decoder.
  • the decoder constructs a motion vector predictor candidate list similarly to the encoder, and derives a motion vector predictor of the current processing block using the motion information of the candidate block indicated by the motion reference flag received from the encoder in the motion vector predictor candidate list.
  • the decoder obtains a motion vector value for the current processing block by using the derived motion vector prediction value and the motion vector difference value transmitted from the encoder.
  • the decoder generates a prediction block for the current processing block based on the derived motion information (ie, motion compensation).
  • the first spatial motion candidate is selected from the set of ⁇ A0, A1 ⁇ located on the left side
  • the second spatial motion candidate is selected from the set of ⁇ B0, B1, B2 ⁇ located above.
  • the candidate configuration is terminated, but if less than two, the temporal motion candidate is added.
  • FIG. 8 is a diagram illustrating an inter prediction method as an embodiment to which the present invention is applied.
  • a decoder decodes a motion parameter for a processing block (eg, a prediction unit) (S801).
  • the decoder may decode the merge index signaled from the encoder.
  • the motion parameter of the current processing block can be derived from the motion parameter of the candidate block indicated by the merge index.
  • the decoder may decode horizontal and vertical motion vector difference (MVD), reference index, and inter prediction mode signaled from the encoder.
  • the motion vector prediction value may be derived from the motion parameter of the candidate block indicated by the motion reference flag, and the motion vector value of the current processing block may be derived using the motion vector prediction value and the received motion vector difference value.
  • the decoder performs motion compensation on the prediction unit by using the decoded motion parameter (or information) (S802).
  • the encoder / decoder performs motion compensation that predicts an image of the current unit from a previously decoded picture by using the decoded motion parameter.
  • FIG. 9 is a diagram illustrating a motion compensation process as an embodiment to which the present invention may be applied.
  • FIG. 9 illustrates a case in which a motion parameter for a current block to be encoded in a current picture is unidirectional prediction, a second picture in LIST0, LIST0, and a motion vector (-a, b). do.
  • the current block is predicted using values of positions (ie, sample values of reference blocks) that are separated from the current block by (-a, b) in the second picture of LIST0.
  • another reference list (eg, LIST1), a reference index, and a motion vector difference value are transmitted so that the decoder derives two reference blocks and predicts the current block value based on the reference block.
  • Optical flow refers to the movement pattern of an object, surface or edge in the field of view.
  • the difference between the images of a certain time and the previous time is sequentially extracted to obtain a pattern of the movement of an object. This makes it possible to obtain more information about the motion than simply the difference between the current frame and the previous frame.
  • Optical flow is a very important contribution to the visual cognitive function of a visual animal, helping to find the target of a moving object and helping to understand the structure of the surrounding environment.
  • the computer vision system may be used to interpret 3D images or to compress images. There are several ways to realize optical flow.
  • the motion of the object may be expressed by Equation 1.
  • I (x, y, t) represents the pixel value of the (x, y) coordinate at time t
  • ⁇ represents the amount of change.
  • ⁇ x represents the amount of change in the x coordinate
  • ⁇ y represents the amount of change in the y coordinate
  • ⁇ t represents the amount of change in time t.
  • Equation 1 Assuming a small movement for a short time, the right term in Equation 1 can be expressed as a first-order equation of Taylor series, and can be developed as in Equation 2.
  • Equation 2 is summarized as in Equation 3.
  • V_x and V_y mean the x-axis component and the y-axis component of the optical flow motion vector (OF motion vector) at I (x, y, t), respectively.
  • ⁇ I / ⁇ x, ⁇ I / ⁇ y, and ⁇ I / ⁇ t represent the derivatives of the x-axis, y-axis, and t-axis directions in I (x, y, t), respectively.
  • Each may be referred to as I_x, I_y, and I_t.
  • the optical flow motion vector is a motion vector derived for motion compensation (ie, BIO) on a pixel basis, and may also be referred to as an optical flow, a motion vector on a pixel basis, a displacement vector, or the like.
  • Equation 3 is expressed in a matrix form, it can be expressed as Equation 4.
  • equation (4) is the same as equation (5).
  • Equation 6 a square error E, which is an LS estimator, may be designed as shown in Equation 6.
  • LS estimator such as Equation 6 may be designed considering the following two things.
  • Equation 6 is summarized as Equation 7 such that the partial differential values for V_x and V_y are zero.
  • Equation 8 If the matrix M, b is defined as Equation 8, it is as follows.
  • Equation (7) is summarized using Equation (8).
  • optical flow V by the LS estimator is determined as in Equation 10.
  • Bidirectional Optical Flow BIO: Bi -directional Optical Flow
  • the BIO is a method of obtaining a motion vector and a reference sample (or prediction sample) value in units of samples (pixels) without transmitting an additional motion vector (MV) using an optical flow.
  • FIG. 10 illustrates, as an embodiment to which the present invention may be applied, a bidirectional prediction method of a picture having a steady motion.
  • a bidirectional reference picture (Ref: 1020, 1030) exists around a current picture (or B-slice) 1010 is illustrated. .
  • a motion vector (hereinafter referred to as a 'second motion vector') 1032 from a corresponding pixel (hereinafter referred to as a 'second corresponding pixel') 1031 to a B position in 1 (1030) is represented by a symmetric value. Can be.
  • first motion vector 1022 and the second motion vector 1032 may be expressed as vectors having the same size and opposite directions.
  • Equation (11) the difference between the pixel values at the A position and the B position is summarized as in Equation (11).
  • I ⁇ 0 [i + v_x, j + v_y] is the pixel value of the A position of reference picture 0 (Ref0) 1020 and I ⁇ 1 [i-v_x, j-v_y] is the reference picture 1 (Ref1) Pixel value at position B of 1030. And (i, j) means the coordinates of the current pixel 1011 in the current picture 1010.
  • Each pixel value may be expressed as in Equation 12.
  • Equation 12 Substituting Equation 12 into Equation 11 may be arranged as in Equation 13.
  • I_x ⁇ (0) [i, j] and I_y ⁇ (0) [i, j] are the x- and y-axis partial derivatives at the first corresponding pixel position in reference picture 0 (Ref0) 1020
  • I_x ⁇ (1) [i, j] and I_y ⁇ (1) [i, j] are partial derivative values of the x-axis and y-axis at the second corresponding pixel position of the reference picture 1 (Ref1) 1030, and [i, j] Position The gradient (or gradient, gradient) of the pixel.
  • Table 1 shows the interpolation filter coefficients that can be used to calculate the BIO gradient (or gradient, amount of change).
  • the BIO gradient can be determined using the interpolation filter of Equation 14 and Table 1 below.
  • ⁇ _x ⁇ (k) denotes the fractional part of the motion vector in the x-axis direction
  • dF_n ( ⁇ _x ⁇ (k)) denotes the coefficient of the nth filter tap in ⁇ _x ⁇ (k).
  • R ⁇ (k) [i + n, j] means the reconstruction pixel value of the [i + n, j] coordinate in the reference picture k (k is 0 or 1).
  • the purpose is to find a motion vector having a pixel value at the A position in the reference picture 0 (1020) and a pixel value at the B position in the reference picture 1 (1030) having the same value (or the minimum difference value). Since the error between pixels can be large, a motion vector having a minimum difference between pixel values within a predetermined window size can be found.
  • G_x represents the gradient on the x-axis (i.e. horizontal direction)
  • G_y represents the gradient on the y-axis (i.e. vertical direction)
  • ⁇ P is the gradient on the t-axis (or pixel over time). Change in value).
  • Equation 13 In consideration of the regionally fixed motion, each term in Equation 13 is substituted by Equation 15 to obtain Equation 16.
  • Equation 16 is divided into partial partial derivatives of V_x and V_y, respectively.
  • S1 to S12 may be defined as shown in Equation 18 to calculate V_x and V_y.
  • Equation 18 V_x and V_y in Equation 17 are arranged as in Equation 19, respectively.
  • the predictor of the current pixel may be calculated using V_x and V_y as shown in Equation 20 below.
  • P represents a predictor for the current pixel in the current block.
  • P ⁇ (0) and P ⁇ (1) represent respective pixel values of pixels (ie, a first corresponding pixel and a second corresponding pixel) that are collocated with the current pixel in the L0 reference block and the L1 reference block, respectively. .
  • Equation 19 When the encoder / decoder calculates a pixel-by-pixel motion vector using Equation 19, a large amount of computation may be required. Therefore, in order to reduce the computational complexity, Equation 19 may be approximated and used as in Equation 21.
  • the BIO method that is, the optical flow motion vector refinement method, may be performed in a motion compensation process when bi-directional prediction is applied to the current block. A detailed method will be described with reference to the drawings below.
  • FIG. 11 is a diagram illustrating a motion compensation method through bidirectional prediction according to an embodiment of the present invention.
  • the encoder / decoder determines whether true bi-prediction is applied to the current block (S1101).
  • reference picture 0 (Ref0) and reference picture 1 (Ref1) are opposite in the time axis with respect to the current block (or the current picture). (I.e., when the Picture Order Count (POC) of the current picture is between the POCs of two reference pictures).
  • POC Picture Order Count
  • step S1101 when true bidirectional prediction is applied to the current block, the encoder / decoder obtains a gradient map of the current block (S1102).
  • the width and height of the current block (PU) are w and h, respectively, and the encoder / decoder corresponds to each correspondence in a block of size (w + 4) ⁇ (h + 4).
  • Gradients for each of the x and y axes of the pixel may be obtained and determined as gradient maps of the x and y axes, respectively.
  • FIG. 12 is a diagram illustrating a method of determining a gradient map according to an embodiment of the present invention.
  • the size of the current block 1201 is 8 ⁇ 8.
  • a 5 ⁇ 5 sized window 1202 is applied to the 8 ⁇ 8 sized current block 1201, a 12 ⁇ 12 sized gradient map may be determined.
  • the encoder / decoder calculates values S1 to S6 using a 5 ⁇ 5 window (1201 in FIG. 12) (S1103).
  • S1 to S6 values may be calculated using Equation 18 described above.
  • the encoder / decoder determines the optical flow motion vector (OF motion vector) of the current pixel (S1104).
  • the encoder / decoder calculates an optical flow predictor (OF predictor), and determines the calculated optical flow predictor as an optimal predictor (S1105).
  • OF predictor optical flow predictor
  • the encoder / decoder may calculate a predicted value for the current pixel using Equation 20, using the optical flow motion vector (or the motion vector in pixels) determined in step S1104, and optimize the predicted value for the calculated current pixel. It may be determined as the predicted value of (or the final predicted value of the current pixel).
  • step S1101 If it is determined in step S1101 that true bidirectional prediction is not applied to the current block, the encoder / decoder performs bidirectional prediction to calculate a bi-directional predictor, and the calculated bidirectional predictor is optimized. predictor) (S1106).
  • motion compensation on a pixel basis based on the optical flow may not be performed.
  • FIG. 13 is a diagram illustrating a method of determining an optical flow motion vector according to an embodiment of the present invention.
  • FIG. 13 a method of determining a horizontal component (ie, an x-axis component) of an optical flow motion vector (or a pixel-based motion vector) will be described.
  • the encoder / decoder determines whether the S1 value is larger than a specific threshold (S1301).
  • step S1302 when the S1 value is larger than the threshold value, the encoder / decoder obtains a V_x value (S1302).
  • the encoder / decoder may calculate the V_x value using Equation 19 or Equation 21 as described above.
  • the encoder / decoder determines whether the V_x value obtained in step S1302 is greater than a limit value (S1303).
  • step S1303 when the V_x value is larger than the threshold value, the encoder / decoder sets the V_x value as the threshold value (S1304).
  • step S1303 If it is determined in step S1303 that the V_x value is not greater than the threshold value, the value calculated in step S1302 is determined as the V_x value.
  • step S1301 If it is determined in step S1301 that the S1 value is not greater than the threshold value, the encoder / decoder sets the V_x value to 0 (S1306).
  • the encoder / decoder may determine an optical flow motion vector in the y axis direction (that is, a horizontal component of the optical flow motion vector (or a motion vector in pixels)) in a similar manner to the method described with reference to FIG. 13.
  • the encoder / decoder determines whether the S5 value is greater than a specific threshold value, and if the S5 value is larger than the threshold value, calculates the V_y value using Equation 19 or Equation 21. Then, it is determined whether the calculated V_y value is greater than the limit value, and if the calculated V_y value is greater than the limit value, the encoder / decoder sets the V_y value as the limit value. If the calculated V_y value is not greater than the limit value, the calculated value V_y is determined. And if the S5 value is not greater than the threshold, the encoder / decoder sets the V_y value to zero.
  • the encoder / decoder may calculate an optical flow predictor (OF predictor) to which optical motion motion vector refinement is applied in units of pixels using Equation 20.
  • OF predictor optical flow predictor
  • the existing Bi-directional Optical Flow (BIO) method is known to work well when the image contains enough gradient (or gradient, gradient) components. Therefore, as described above, the conventional BIO method is performed when the gradient component in the horizontal direction and the vertical direction exceeds the threshold in pixels.
  • the existing BIO method that is, the optical flow motion vector refinement (OF MV refinement) method
  • OF MV refinement optical flow motion vector refinement
  • Table 2 shows a case where the bi-predictor generated by performing bi-directional inter prediction for each block size is excellent and the BIO predictor generated by applying the existing BIO method is excellent. Represents the ratio of.
  • the predictor having a smaller absolute value of the difference between the original image and the predictor in each pixel corresponds to the prediction of the original image more accurately, the predicted value is determined as an excellent predictive value.
  • the overall ratio of the better BIO predictor ie, OF-predictor
  • the ratio of the better bi-predictor is also higher.
  • the present invention proposes a method of selectively using a bidirectional prediction value and a BIO prediction value to enhance coding efficiency.
  • FIG. 14 is a diagram for describing a motion compensation method in units of pixels as an embodiment to which the present invention can be applied.
  • FIG. 14A illustrates blocks with improved coding efficiency
  • FIG. 14B illustrates blocks with reduced coding efficiency.
  • the gradient component in the block is large but the direction of the gradient component is monotonous.
  • the gradient component in the block is large as in the case of FIG. 14A, but the directionality of the gradient component in the block can be observed to be high in complexity.
  • the coding efficiency when the BIO prediction value is used is a bidirectional prediction value. It may be lower than the coding efficiency when using.
  • the method of selectively using the bidirectional prediction value and the BIO prediction value proposed in the present specification may be performed independently of the x-axis direction and the y-axis direction as in the conventional BIO method.
  • the gradient complexity may be referred to as a change amount complexity, a directional complexity of the change amount component, a directional complexity of the gradient component, a directional complexity, a gradient directional complexity, and the like.
  • a gradient represents a horizontal or vertical partial derivative (or change) value in a window area
  • a gradient represents a change amount (or slope, or change) in pixel values of a plurality of horizontal or vertical pixels in the window area. Increase or decrease), or may be calculated using a predetermined interpolation filter (see, for example, Table 1 and Equation 14 above).
  • Gradient complexity refers to the degree of complexity of motion in a region of a certain size. If the gradient value is complexly distributed within a region of a certain size, it may be estimated that the region has a complex and distributed motion. Accordingly, the encoder / decoder may determine whether to perform pixel-based motion compensation (ie, BIO) based on the gradient complexity.
  • pixel-based motion compensation ie, BIO
  • the gradient complexity may be referred to as a gradient complexity, a directional complexity of a gradient component, a directional complexity, and the like.
  • This embodiment proposes a method of determining whether to perform optical flow based motion compensation on a pixel-by-pixel basis by determining the directional complexity of gradient components in a window region of a specific size.
  • the present embodiment defines a window gradient complexity (WGC) in order to determine the degree of difference in the motion of an object in a window of a specific size.
  • WGC window gradient complexity
  • WGC is a variable representing the directional complexity of gradient components in a window of a specific size.
  • the name is not limited thereto.
  • an N ⁇ N window may be used to determine the directional complexity of the gradient component.
  • a description will be given on the assumption of a 5 ⁇ 5 sized window for convenience of description, but the size of the window for the implementation of the present invention is not limited to 5 ⁇ 5 sized.
  • the encoder / decoder may perform motion compensation on a pixel basis only when the WGC is smaller than a specific threshold. As described above, determination of whether to perform pixel-by-pixel motion compensation may be performed independently of the x-axis direction and the y-axis direction. It will be described in detail with reference to the drawings below.
  • 15 is a diagram illustrating a method of determining an optical flow motion vector according to an embodiment of the present invention.
  • FIG. 15 illustrates a method of determining a horizontal component (x-axis component) of an optical flow motion vector (or a motion vector in pixels).
  • the encoder / decoder determines whether the S1 value is larger than the first threshold value TH1 and the WGC_x value is smaller than the second threshold value TH2 (S1501).
  • the first threshold value represents a threshold value applied to determine the magnitude of the gradient component
  • the second threshold value represents a threshold value applied to determine the directional complexity of the gradient component.
  • WGC_x represents a horizontal direction (x-axis direction) component of WGC.
  • step S1501 when the S1 value is larger than the first threshold value TH1 and the WGC_x value is smaller than the second threshold value TH2, the encoder / decoder obtains a V_x value (S1502).
  • the encoder / decoder may calculate the V_x value using Equation 19 or Equation 21 as described above.
  • the encoder / decoder determines whether the V_x value obtained in step S1502 is greater than a limit value (S1503).
  • step S1503 when the V_x value is larger than the threshold value, the encoder / decoder sets the V_x value as the threshold value (S1504).
  • step S1503 If it is determined in step S1503 that the V_x value is not greater than the threshold value, the value calculated in step S1502 is determined as the V_x value.
  • step S1501 If it is determined in step S1501 that the S1 value is not greater than the first threshold value or the WGC_x value is not smaller than the second threshold value, the encoder / decoder sets the V_x value to 0 (S1506).
  • the encoder / decoder may determine the optical flow motion vector in the y-axis direction (that is, the horizontal component of the optical flow motion vector (or the pixel-by-pixel motion vector)) in a manner similar to the method described with reference to FIG. 15.
  • the encoder / decoder determines whether the S5 value is greater than the first threshold TH1, or whether the WGC_y value is less than the second threshold TH2, and if the S5 value is greater than the first threshold S5. If the value is large and the WGC_y value is smaller than the second threshold value, the V_y value is calculated using Equation 19 or Equation 21. Then, it is determined whether the calculated V_y value is greater than the limit value, and if the calculated V_y value is greater than the limit value, the encoder / decoder sets the V_y value as the limit value. If the calculated V_y value is not greater than the limit value, the calculated value V_y is determined. And if the S5 value is not greater than the first threshold or the WGC_y value is not less than the second threshold, the encoder / decoder sets the V_y value to zero.
  • WGC_y represents a vertical direction (y axis direction) component of the WGC.
  • the encoder / decoder calculates the optical flow predictor (or BIO predictor) to which the optical motion motion vector refinement is applied in units of pixels using Equation 20. Can be.
  • the encoder / decoder derives an optical flow motion vector (motion vector in pixel) only when the WGC value in each of the horizontal direction and the vertical direction is smaller than the threshold value (second threshold value) to perform motion compensation per pixel. .
  • WGC can be defined in many different ways.
  • a variable WGC that can be used to indicate the directional complexity of the gradient component is described below by way of example. However, this is only an example and the present invention is not limited thereto.
  • WGC may be defined as in Equation 22.
  • S1 (i, j) and S5 (i, j) may be calculated by Equation 18 described above. That is, S1 (i, j) represents the sum of squares of the horizontal gradient component in a window centered on a pixel whose coordinate is [i, j], and S5 (i, j) has a coordinate of [i, j]. The sum of squares of the gradient components in the vertical direction in the window centered on the pixel.
  • the horizontal component and the vertical component WGC_x and WGC_y of the WGC may be determined equally, and may be equal to the sum of squares of the horizontal gradient component of the current pixel of the [i, j] coordinate in the window. It can be calculated from a function f () which takes as input the sum of squares of the vertical gradient components.
  • the function f () may be a function for outputting an average value, a minimum value, or a maximum value of two inputs.
  • WGC may be defined as in Equation 23.
  • the WGC may be determined using a gradient value of each pixel in the window.
  • G_x (i, j) and G_y (i, j) (where i, j ⁇ ⁇ 0, 1, ..., N ⁇ ) are each [i] in a 5 ⁇ 5 window (1202 in FIG. 12 above).
  • j] The horizontal component and the vertical component of the gradient of the position pixel may be calculated using Equation 15 described above.
  • WGC_x which is a horizontal component of WGC
  • WGC_y which is a vertical component of the WGC
  • WGC_x may be calculated from a function g () which takes as input the vertical gradient component of all pixels in the window.
  • the function g () may be a function of outputting an average value, a minimum value, a maximum value, or a variance value by inputting gradient values of pixels in the window.
  • the WGC may be calculated as in Equation (24).
  • dG_x (i, j) and dG_y (i, j) (where i, j ⁇ ⁇ 0, 1, ..., N ⁇ ) may be defined as in Equation 25.
  • G_x (i, j) is the horizontal gradient of the [i, j] position pixel
  • G_y (i, j) is [i, j] means the vertical gradient of the position pixel
  • dG_x (i-p, j-q) represents a difference value between a horizontal component of the gradient of the [i-p, j-q] coordinate pixel and a horizontal component of the gradient of the [i, j] coordinate pixel.
  • DG_y (i-p, j-q) represents the difference value between the vertical component of the gradient of the [i-p, j-q] coordinate pixel and the vertical component of the gradient of the [i, j] coordinate pixel.
  • the WGC may be determined using a difference value between a gradient value of each pixel in the window area and a gradient value of pixels in the window area.
  • WGC_x inputs the difference values of the horizontal component of the gradient component of each pixel and the horizontal component of the gradient of the current pixel in a 5 ⁇ 5 window area centered on the current pixel of [i, j] coordinates. Can be calculated from the function h ().
  • WGC_y is a function that inputs difference values between the vertical component of the gradient of each pixel and the vertical component of the gradient of the current pixel in a 5 ⁇ 5 window area centered on the current pixel at [i, j] coordinates. can be calculated from h ().
  • the function h () may be a function of outputting an average value, a minimum value, a maximum value, or a variance value by inputting gradient difference values of pixels in the window.
  • WGC may be calculated as in Equation 26.
  • getNumMinusOne () is a function for obtaining the number of -1 of the input variables
  • getNumPlusOne () is a function for obtaining the number of +1 of the input variables. That is, N_1 and N _ (-1) mean the numbers of +1 and -1, respectively.
  • the signum function sign () is defined as in Equation 27.
  • the signum function of Equation 27 outputs 0 when the input is 0, -1 when the input is less than 0, and 1 when the input exceeds 0. That is, the sign of the input value can be determined using the signum function.
  • the WGC may be determined by using a sign of a difference value between a gradient value of a current pixel and a gradient value of pixels in a window area.
  • WGC_x is a negative sign of the difference between the horizontal component of the gradient component of each pixel and the horizontal component of the gradient of the current pixel in a 5 ⁇ 5 window area centered on the current pixel at [i, j] coordinates. It can be calculated from a function u () taking the number and the number of positive signs as input. WGC_y is the number of negative signs of the difference between the vertical component of the gradient component of each pixel and the vertical component of the gradient of the current pixel in a 5 ⁇ 5 window area centered on the current pixel at [i, j] coordinates. And a function u () taking a positive number of signs as input.
  • the function u () takes as input the negative number of signs (i.e., N _ (-1)) and the positive number of signs (i.e., N_1), and the average, minimum, maximum, variance, or negative number of signs. It may be a function that outputs a difference value of the number of positive signs.
  • the present embodiment proposes a method of determining whether to perform optical flow based motion compensation on a block basis by determining a directional complexity of a gradient in a gradient map.
  • block gradient complexity (BGC) is defined.
  • BGC is a variable representing the directional complexity of gradient components in a gradient map of a specific size.
  • the name is not limited thereto.
  • an N ⁇ N window may be used to determine the directional complexity of the gradient component.
  • a description will be given on the assumption of a 5 ⁇ 5 sized window for convenience of description, but the size of the window for the implementation of the present invention is not limited to 5 ⁇ 5 sized.
  • the encoder / decoder may perform motion compensation on a pixel-by-pixel basis (ie, optical flow-based motion compensation) only when the BGC is smaller than a specific threshold.
  • determination of whether to perform optical flow based motion compensation may be independently performed with respect to the x axis direction and the y axis direction. It will be described in detail with reference to the drawings below.
  • 16 is a diagram illustrating a motion compensation method through bidirectional prediction according to an embodiment of the present invention.
  • the encoder / decoder determines whether true bi-prediction is applied to the current block (S1601).
  • reference picture 0 (Ref0) and reference picture 1 (Ref1) are opposite in the time axis with respect to the current block (or the current picture). (I.e., when the Picture Order Count (POC) of the current picture is between the POCs of two reference pictures).
  • POC Picture Order Count
  • step S1601 when true bidirectional prediction is applied to the current block, the encoder / decoder obtains a gradient map of the current block (S1602).
  • the width and height of the current block (PU) are w and h, respectively, and the encoder / decoder corresponds to each correspondence in a block of size (w + 4) ⁇ (h + 4).
  • Gradients for each of the x and y axes of the pixel may be obtained and determined as gradient maps of the x and y axes, respectively.
  • the encoder / decoder determines the BGC, and determines whether the determined BGC value exceeds a specific threshold value (S1603).
  • step S1603 when the BGC value does not exceed a specific threshold value, the encoder / decoder calculates the values S1 to S6 using a 5 ⁇ 5 window (1201 in FIG. 12) (S1604).
  • the encoder / decoder performs motion compensation (optical flow based motion compensation) on a pixel basis only when the BGC value is smaller than the threshold value.
  • S1 to S6 values may be calculated using Equation 18 described above.
  • step S1603 If it is determined in step S1603 that the BGC value exceeds a certain threshold value, the encoder / decoder calculates the bi-directional predictor by performing the bidirectional prediction by the encoder / decoder and optimizes the calculated bidirectional predictor. Determined by the predictive predictor.
  • the encoder / decoder determines the optical flow motion vector (OF motion vector) of the current pixel (S1605).
  • the encoder / decoder calculates an optical flow predictor (OF predictor), and determines the calculated optical flow predictor as an optimal predictor (S1606).
  • OF predictor optical flow predictor
  • the encoder / decoder may calculate the prediction value for the current pixel using the optical flow motion vector (or the pixel-by-pixel motion vector) determined in operation S1605 as shown in Equation 20, and optimize the calculated prediction value for the current pixel. It may be determined as the predicted value of (or the final predicted value of the current pixel).
  • step S1601 If it is determined in step S1601 that the true bidirectional prediction is not applied to the current block, the encoder / decoder performs bidirectional prediction to calculate a bi-directional predictor and uses the calculated bidirectional predictor as an optimal prediction value. predictor) (S1607).
  • BGC can be defined in a variety of ways.
  • a variable BGC that can be used to indicate the directional complexity of the gradient component is described below by way of example. However, this is only an example and the present invention is not limited thereto.
  • S1 (i, j) and S5 (i, j) may be calculated by Equation 18 described above.
  • i, j ⁇ ⁇ 0, 1, 2, 3,... , N + 3 ⁇ , and N denotes the size (ie, N ⁇ N) of a coding block (eg PU).
  • the gradient map may be determined as (N + 4) ⁇ (N + 4).
  • the horizontal component BGC_x and the vertical component BGC_y of BGC may be determined to be the same, and the sum of squares of the horizontal gradient component and the vertical gradient component of each pixel in the gradient map is input. Can be calculated from the function f ().
  • the function f () may be a function for outputting an average value, a variance value, a minimum value, or a maximum value.
  • BGC may be defined as in Equation 29.
  • BGC may be determined using a gradient value of each pixel in the gradient map.
  • G_x (i, j) and G_y (i, j) (where i, j ⁇ ⁇ 0, 1,..., N + 3 ⁇ ) are the [i, j] position pixels in the gradient map of the current block.
  • the horizontal component of the gradient, the vertical component of the can be calculated using the above equation (15).
  • BGC_x which is a horizontal component of BGC
  • BGC_y which is a vertical component of BGC
  • BGC_x which is a horizontal component of BGC
  • BGC_y which is a vertical component of BGC
  • g () which takes as input a vertical gradient component of all pixels in the gradient map.
  • the function g () may be a function of outputting an average value, a minimum value, a maximum value, or a variance value by inputting gradient values of pixels in the window.
  • BGC may be calculated as in Equation 30.
  • dG_x (i, j) and dG_y (i, j) (i, j ⁇ ⁇ 0, 1, ..., N ⁇ ) may be defined as in Equation 31.
  • dG_x (i, j) and dG_y (i, j) may be defined as in Equation 32.
  • G_x (i, j) means a horizontal gradient of the [i, j] position pixel
  • G_y (i, j) means a vertical gradient of the [i, j] position pixel
  • dG_x (i, j) is the difference or difference between the horizontal component of the gradient of the [i, j] coordinate pixel and the horizontal component of the gradient of the [i + 1, j] coordinate pixel.
  • DG_y (i, j) represents the absolute value of the difference value or the difference value between the vertical component of the gradient of the [i, j] coordinate pixel and the vertical component of the gradient of the [i, j + 1] coordinate pixel.
  • the WGC may be determined using a difference value between a gradient value of each pixel in the gradient map and a gradient value of a pixel adjacent to the current pixel.
  • WGC_x is obtained from a function h () which inputs the difference values (or absolute values of the difference values) of the horizontal component of the gradient of each pixel in the gradient map and the horizontal component of the gradient of the pixel adjacent to the right side of the pixel. Can be calculated.
  • WGC_y is inputted from a function h () that inputs difference values (or absolute values of the difference values) of the vertical component of the gradient of each pixel in the gradient map and the vertical component of the gradient of the adjacent pixel at the bottom of the pixel. Can be calculated.
  • the function h () may be a function of outputting an average value, a minimum value, a maximum value, or a variance value by inputting gradient difference values (or absolute values of the difference values) of each pixel in the gradient map.
  • the BGC is defined as in the third example (Equation 30) described above, and may define the difference value (ie, input of the function h ()) used in the calculation of the BGC as in Equation 33.
  • E [Gx (k, l)] means a gradient average value or median of the gradient map of the current block.
  • dG_x (i, j) represents a difference value between the horizontal gradient of the [i, j] coordinate pixel and the average value (or median) of the horizontal gradient of the pixels in the gradient map.
  • dG_y (i, j) represents a difference value between the vertical gradient of the [i, j] coordinate pixel and the average value (or median) of the vertical gradient of the pixels in the gradient map.
  • WGC_x may be calculated from a function h () which takes as inputs the difference values between the horizontal gradient of each pixel in the gradient map and the horizontal mean value (or median) of the gradient map.
  • WGC_y may be calculated from a function h () which inputs difference values between a vertical gradient of each pixel in the gradient map and a vertical mean value (or median) of the gradient map.
  • Embodiments 1 and 2 described above may be performed separately or simultaneously. For example, even when it is determined whether optical flow based motion compensation is performed on a block basis, it may be further determined whether optical flow based motion compensation is performed on a pixel basis.
  • 17 is a diagram illustrating an inter prediction based image processing method according to an embodiment of the present invention.
  • the encoder / decoder performs motion compensation on a block basis by performing bidirectional inter prediction based on the motion vector of the current block (S1701).
  • the encoder / decoder may perform motion compensation by using the inter prediction method described above with reference to FIGS. 5 to 9, and generate a bidirectional prediction value of each pixel constituting the current block.
  • the encoder / decoder uses a gradient representing a change amount of a pixel value in a horizontal direction or a vertical direction with respect to each pixel in a region of a specific size of the first reference picture and the second reference picture of the current block.
  • Gradient complexity representing the complexity of the motion (motion) in the area of the size is calculated (S1702).
  • the gradient complexity may be calculated in units of pixels or in blocks.
  • the region of the specific size may include a first window centered on a pixel that is collocated with the current pixel in the first and second reference blocks of the current block. ) Area.
  • the gradient complexity may be calculated using the gradient value of each pixel in the first window area.
  • the gradient complexity may be calculated using the sum of squares of horizontal components of the gradient and the sum of vertical components of the gradient in the first window area.
  • the gradient complexity is calculated by using a difference value between a gradient value of a pixel having the same coordinate as the current pixel and a gradient value of each pixel in the first window area. Prediction mode based image processing method.
  • the gradient complexity is a sign of a difference value between a gradient value of a pixel having the same coordinate as the current pixel and a gradient value of each pixel in the first window area. Can be calculated using.
  • the region having a specific size may be a second window region including the first reference block and the second reference block.
  • the specific size region includes (W + 4) ⁇ (H +) including the first reference block and the second reference block when the size of the current block is W ⁇ H. 4) may be an area of size.
  • the gradient complexity may be calculated using the gradient value of each pixel in the second window area.
  • the gradient complexity may be calculated using the sum of squares of the horizontal components and the vertical components of the gradient in the second window area.
  • the gradient complexity may be calculated using a difference value of a gradient value of each pixel in the second window area and a gradient value of a pixel adjacent to each pixel.
  • the gradient complexity may be calculated using a difference value between a gradient value of each pixel in the second window area and an average value of the gradient in the second window area.
  • the encoder / decoder has a first window centered around a pixel that is collocated with the current pixel in the first and second reference blocks of the current block if the gradient complexity is less than a certain threshold.
  • a motion vector in pixel units of the current pixel is derived using a gradient in an area (S1703).
  • the encoder / decoder may perform optical flow based motion compensation in the method described above with reference to FIGS. 11 to 13 in units of pixels in the current block.
  • the gradient complexity may be calculated in pixel units or in block units.
  • the encoder / decoder generates a predictor of the current pixel by adjusting the bidirectional predictive value based on the motion vector of the pixel unit (S1704).
  • the encoder / decoder performs motion compensation on a pixel-by-pixel basis (ie, optical flow motion compensation) only when the gradient complexity is smaller than a specific threshold.
  • the encoder / decoder may determine the bidirectional predicted value generated by performing block compensation in step S1701 as the prediction value of the current pixel.
  • FIG. 18 is a diagram illustrating an inter predictor according to an embodiment of the present invention.
  • the inter prediction unit 181 (see FIG. 1; see 261 and FIG. 2) is illustrated as one block for convenience of description, but the inter prediction units 181 and 261 are included in the encoder and / or the decoder. It can be implemented as.
  • the inter prediction units 181 and 261 implement the functions, processes, and / or methods proposed in FIGS. 5 to 20.
  • the inter predictors 181 and 261 may include a bidirectional predictive value generator 1801, a gradient complexity calculator 1802, a pixel-by-pixel motion vector derivator 1803, and a predictive value generator 1804. have.
  • the bidirectional predictive value generator 1801 performs bidirectional inter prediction based on the motion vector of the current block to perform motion compensation on a block basis.
  • the bidirectional predictive value generator 1801 may perform motion compensation by using the inter prediction method described above with reference to FIGS. 5 to 9, and generate a bidirectional predictive value of each pixel constituting the current block.
  • the gradient complexity calculator 1802 uses a gradient indicating an amount of change in a pixel value in a horizontal direction or a vertical direction with respect to each pixel in a region of a specific size of the first reference picture and the second reference picture of the current block. Then, the gradient complexity (gradient complexity) representing the degree of complexity of the motion (motion) in the region of the particular size is calculated.
  • the gradient complexity may be calculated in units of pixels or in blocks.
  • the region of the specific size may include a first window centered on a pixel that is collocated with the current pixel in the first and second reference blocks of the current block. ) Area.
  • the gradient complexity may be calculated using the gradient value of each pixel in the first window area.
  • the gradient complexity may be calculated using the sum of squares of horizontal components of the gradient and the sum of vertical components of the gradient in the first window area.
  • the gradient complexity is calculated by using a difference value between a gradient value of a pixel having the same coordinate as the current pixel and a gradient value of each pixel in the first window area. Prediction mode based image processing method.
  • the gradient complexity is a sign of a difference value between a gradient value of a pixel having the same coordinate as the current pixel and a gradient value of each pixel in the first window area. Can be calculated using.
  • the region having a specific size may be a second window region including the first reference block and the second reference block.
  • the specific size region includes (W + 4) ⁇ (H +) including the first reference block and the second reference block when the size of the current block is W ⁇ H. 4) may be an area of size.
  • the gradient complexity may be calculated using the gradient value of each pixel in the second window area.
  • the gradient complexity may be calculated using the sum of squares of the horizontal components and the vertical components of the gradient in the second window area.
  • the gradient complexity may be calculated using a difference value of a gradient value of each pixel in the second window area and a gradient value of a pixel adjacent to each pixel.
  • the gradient complexity may be calculated using a difference value between a gradient value of each pixel in the second window area and an average value of the gradient in the second window area.
  • the pixel-by-pixel motion vector derivation unit 1803 is based on pixels that have the same coordinates as the current pixels in the first and second reference blocks of the current block when the gradient complexity is smaller than a specific threshold.
  • a motion vector in pixel units of the current pixel is derived by using a gradient in a first window area.
  • the pixel-by-pixel motion vector derivation unit 1803 performs optical flow based motion compensation in the method described above with reference to FIGS. 11 to 13 when the gradient complexity is smaller than a specific threshold. Can be done.
  • the prediction value generator 1804 generates a predictor of the current pixel by adjusting the bidirectional prediction value based on the motion vector of the pixel unit.
  • the prediction value generator 1804 performs motion compensation (ie, optical flow motion compensation) in units of pixels only when the gradient complexity is smaller than a specific threshold value.
  • the prediction value generator 1804 may determine the bidirectional prediction value generated by performing the block compensation in the bidirectional prediction value generator 1801 as the prediction value of the current pixel. .
  • each component or feature is to be considered optional unless stated otherwise.
  • Each component or feature may be embodied in a form that is not combined with other components or features. It is also possible to combine some of the components and / or features to form an embodiment of the invention.
  • the order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.
  • Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof.
  • an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), FPGAs ( field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and the like.
  • ASICs application specific integrated circuits
  • DSPs digital signal processors
  • DSPDs digital signal processing devices
  • PLDs programmable logic devices
  • FPGAs field programmable gate arrays
  • processors controllers, microcontrollers, microprocessors, and the like.
  • an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above.
  • the software code may be stored in memory and driven by the processor.
  • the memory may be located inside or outside the processor, and may exchange data with the processor by various known means.

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Abstract

La présente invention concerne un procédé de traitement d'une image basée sur un mode d'inter-prédiction et un dispositif associé. En particulier, le procédé de traitement d'une image sur la base d'une inter-prédiction peut comprendre les étapes consistant : à réaliser une inter-prédiction bidirectionnelle sur la base d'un vecteur de mouvement d'un bloc actuel de façon à générer un prédicteur bidirectionnel d'un pixel actuel à l'intérieur du bloc actuel ; à calculer une complexité de gradient montrant un degré complexe de mouvement dans une zone de taille spécifique en utilisant un gradient dans la zone de taille spécifique d'une première image de référence et d'un second pixel de référence du bloc actuel ; à dériver un vecteur de mouvement d'une unité de pixel du pixel actuel en utilisant un gradient dans une première zone de fenêtre, si la complexité de gradient est inférieure à un seuil spécifique ; et à régler le prédicteur bidirectionnel sur la base du vecteur de mouvement de l'unité de pixel de façon à générer un prédicteur du pixel actuel.
PCT/KR2017/002693 2017-03-13 2017-03-13 Procédé de traitement d'image basée sur un mode d'inter-prédiction et dispositif associé WO2018169099A1 (fr)

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WO2021174396A1 (fr) * 2020-03-02 2021-09-10 Oppo广东移动通信有限公司 Procédé de prédiction d'image, codeur, décodeur et support de stockage
CN115280779A (zh) * 2020-03-20 2022-11-01 北京达佳互联信息技术有限公司 用于仿射运动补偿预测细化的方法和装置
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CN112055222A (zh) * 2020-08-21 2020-12-08 浙江大华技术股份有限公司 视频编解码方法、电子设备及计算机可读存储介质
CN112055222B (zh) * 2020-08-21 2024-05-07 浙江大华技术股份有限公司 视频编解码方法、电子设备及计算机可读存储介质
CN112565768A (zh) * 2020-12-02 2021-03-26 浙江大华技术股份有限公司 一种帧间预测方法、编解码系统及计算机可读存储介质
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