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WO2013111977A1 - Procédé de déblocage et appareil de déblocage pour un bloc sur lequel une prédiction intra est exécutée - Google Patents

Procédé de déblocage et appareil de déblocage pour un bloc sur lequel une prédiction intra est exécutée Download PDF

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Publication number
WO2013111977A1
WO2013111977A1 PCT/KR2013/000580 KR2013000580W WO2013111977A1 WO 2013111977 A1 WO2013111977 A1 WO 2013111977A1 KR 2013000580 W KR2013000580 W KR 2013000580W WO 2013111977 A1 WO2013111977 A1 WO 2013111977A1
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Prior art keywords
block
intra
current block
intra prediction
mode
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PCT/KR2013/000580
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English (en)
Korean (ko)
Inventor
방건
이진영
정원식
허남호
박광훈
김경용
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Electronics and Telecommunications Research Institute ETRI
Kyung Hee University
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Electronics and Telecommunications Research Institute ETRI
Kyung Hee University
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Priority claimed from KR1020130007910A external-priority patent/KR20130086980A/ko
Publication of WO2013111977A1 publication Critical patent/WO2013111977A1/fr
Anticipated expiration legal-status Critical
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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
    • H04N19/85—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using pre-processing or post-processing specially adapted for video compression
    • H04N19/86—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using pre-processing or post-processing specially adapted for video compression involving reduction of coding artifacts, e.g. of blockiness
    • 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
    • H04N19/593—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial prediction techniques

Definitions

  • the present invention relates to a method and apparatus for image encoding / decoding, and more particularly, to a method and apparatus for deblocking a block on which intra prediction is performed.
  • High efficiency image compression techniques can be used to solve these problems caused by high resolution and high quality image data.
  • An inter-screen prediction technique for predicting pixel values included in the current picture from a picture before or after the current picture using an image compression technique an intra prediction technique for predicting pixel values included in a current picture using pixel information in the current picture
  • An object of the present invention is to provide a deblocking method in consideration of a block prediction method.
  • Another object of the present invention is to provide an apparatus for performing a deblocking method in consideration of a block prediction method.
  • the intra prediction method for achieving the above object of the present invention is to determine the intra prediction mode of the plurality of neighboring blocks to predict the plurality of candidate intra screen prediction value of the intra prediction mode of the current block Calculating a mode, determining an intra prediction mode of the current block based on a value of predicting the intra prediction mode of the current block based on the plurality of candidate intra prediction modes, and the intra block mode of the current block;
  • the method may include outputting, as a reconstruction block, a block filtered through a deblocking filter on a prediction block generated based on an intra prediction mode of the current block.
  • the determining of the intra prediction mode of the current block based on a value predicted by the intra prediction mode of the current block based on the plurality of candidate intra prediction modes may include determining a prediction mode within the first candidate screen from a first neighboring block. Deriving a prediction mode in a second candidate screen from a second neighboring block, a prediction mode in a third candidate screen from a third neighboring block, a prediction mode in the first candidate screen, a prediction mode in the second candidate screen, The method may include determining an intra prediction mode of the current block by considering whether at least two intra prediction modes of the third candidate intra prediction modes are the same.
  • outputting a block filtered through a deblocking filter to a prediction block generated based on an intra prediction mode of the current block as a reconstruction block may include a block adjacent to the current block.
  • the method may include determining whether to use the intra skip mode, and determining a filtering method of the deblocking filter based on the determination result.
  • the determining of the filtering method of the deblocking filter based on the determination result may include determining the filtering strength of the deblocking filter as the smallest value when the block adjacent to the current block uses the intra skip mode. If the block adjacent to the current block does not use the intra skip mode, determining whether the block adjacent to the current block used an intra prediction method to determine the filtering strength of the deblocking filter. Can be.
  • the current block may be a block including depth information of an image.
  • the intra prediction method may further include determining whether the current block is encoded in an intra skip mode.
  • the determining of whether the current block is encoded in the intra skip mode may include determining whether the current block is encoded in the intra skip mode based on flag information on whether the current block is intra skip encoded.
  • an image decoding apparatus may determine an intra prediction mode of a plurality of neighboring blocks to determine a prediction value of an intra prediction mode of a current block.
  • the controller may include a filter unit configured to filter a prediction block generated based on an intra prediction mode of the current block through a deblocking filter.
  • the prediction unit induces a prediction mode within a first candidate screen from a first neighboring block, a prediction mode within a second candidate screen from a second neighboring block, and a prediction mode within a third candidate screen from a third neighboring block and then operates within the first candidate screen. It may be implemented to determine an intra prediction mode of the current block by considering whether at least two intra prediction modes of the prediction mode, the second candidate intra prediction mode, and the third candidate intra prediction mode are the same. .
  • the filtering unit may be configured to determine whether a block adjacent to the current block uses the intra skip mode, and determine a filtering method of the deblocking filter based on the determination result.
  • the filtering unit determines the filtering strength of the deblocking filter as the smallest value, and the block adjacent to the current block does not use the intra skip mode. It may be implemented to determine the filtering strength of the deblocking filter by determining whether a block adjacent to the current block uses an intra prediction method.
  • the current block may be a block including depth information of an image.
  • the prediction unit may be implemented to determine whether the current block is encoded in an intra skip mode.
  • the prediction unit may be implemented to determine whether the current block is encoded in the intra skip mode based on flag information on whether the current block is intra skip encoded.
  • a block of a boundary adjacent to a block to which an intra skip skip mode is applied in determining boundary filtering strength of a deblocking filter is determined.
  • boundary filtering may be weakly performed to increase encoding / decoding efficiency and reduce complexity of image encoding / decoding.
  • FIG. 1 is a block diagram illustrating a configuration of an image encoding apparatus according to an embodiment of the present invention.
  • FIG. 2 is a block diagram illustrating a configuration of an image decoding apparatus according to another embodiment of the present invention.
  • FIG. 3 is a conceptual diagram illustrating a method of encoding and decoding a 3D image according to an embodiment of the present invention.
  • FIG. 4 is a conceptual diagram illustrating a depth information map according to an embodiment of the present invention.
  • FIG. 5 is a conceptual diagram illustrating a depth information map according to an embodiment of the present invention.
  • FIG. 6 is a conceptual diagram illustrating an intra prediction method according to an exemplary embodiment of the present invention.
  • FIG. 7 is a conceptual diagram illustrating an intra prediction method according to an exemplary embodiment of the present invention.
  • FIG. 8 is a conceptual diagram illustrating a method of determining boundary filtering strength (bS) of deblocking filtering according to an embodiment of the present invention.
  • FIG. 9 is a conceptual diagram illustrating a boundary between blocks according to an embodiment of the present invention.
  • FIG. 10 is a conceptual diagram illustrating a method of adaptively changing a filtering strength according to an intra prediction mode used when using an intra skip mode according to an embodiment of the present invention.
  • FIG. 11 is a block diagram illustrating a case where an intra prediction method is performed in an intra skip mode according to an embodiment of the present invention.
  • FIG. 12 is a block diagram illustrating a method of configuring a current block image using only prediction blocks using neighboring blocks when in-screen encoding of an image having high correlation between pixels according to an embodiment of the present invention.
  • FIG. 13 is a block diagram illustrating a method of configuring a current block image using only prediction blocks using neighboring blocks when in-screen encoding of an image having high correlation between pixels according to an embodiment of the present invention.
  • first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.
  • the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.
  • each component shown in the embodiments of the present invention are shown independently to represent different characteristic functions, and do not mean that each component is made of separate hardware or one software component unit.
  • each component is included in each component for convenience of description, and at least two of the components may be combined into one component, or one component may be divided into a plurality of components to perform a function.
  • Integrated and separate embodiments of the components are also included within the scope of the present invention without departing from the spirit of the invention.
  • the components may not be essential components for performing essential functions in the present invention, but may be optional components for improving performance.
  • the present invention can be implemented including only the components essential for implementing the essentials of the present invention except for the components used for improving performance, and the structure including only the essential components except for the optional components used for improving performance. Also included in the scope of the present invention.
  • FIG. 1 is a block diagram illustrating a configuration of an image encoding apparatus according to an embodiment of the present invention.
  • the image encoding apparatus 100 may include a motion predictor 111, a motion compensator 112, an intra predictor 120, a switch 115, a subtractor 125, and a converter 130. And a quantization unit 140, an entropy encoding unit 150, an inverse quantization unit 160, an inverse transform unit 170, an adder 175, a filter unit 180, and a reference picture buffer 190.
  • the image encoding apparatus 100 may encode an input image in an intra mode or an inter mode and output a bitstream. In the intra mode, the switch 115 may be switched to intra, and in the inter mode, the switch 115 may be switched to inter. The image encoding apparatus 100 may calculate a prediction block for the input block of the input image and then encode a residual between the input block and the prediction block.
  • Intra mode is defined as intra prediction mode
  • inter mode is inter prediction mode
  • intra prediction unit 120 is intra prediction unit
  • motion predictor 111 and motion compensation unit 112 are defined as inter prediction unit. Can be used.
  • the intra predictor 120 may calculate a prediction block by performing spatial prediction using pixel values of blocks that are already encoded around the current block.
  • the motion predictor 111 may obtain a motion vector by searching for a region that best matches an input block in the reference image stored in the reference picture buffer 190 during the motion prediction process.
  • the motion compensator 112 may calculate a prediction block by performing motion compensation using the motion vector.
  • the subtractor 125 may calculate a residual block by the difference between the input block and the calculated prediction block.
  • the transform unit 130 may output a transform coefficient by performing a transform on the residual block.
  • the transform coefficient may mean a coefficient value calculated by performing transform on the residual block and / or the residual signal.
  • a quantized transform coefficient level calculated by applying quantization to a transform coefficient may also be referred to as a transform coefficient.
  • the quantization unit 140 may output the quantized transform coefficient level by quantizing the input transform coefficient according to the quantization parameter.
  • the entropy encoder 150 may output a bit stream by performing entropy encoding based on values calculated by the quantizer 140 or encoding parameter values calculated in the encoding process.
  • the entropy encoder 150 may use an encoding method such as exponential golomb, context-adaptive variable length coding (CAVLC), or context-adaptive binary arithmetic coding (CABAC) for entropy encoding.
  • CAVLC context-adaptive variable length coding
  • CABAC context-adaptive binary arithmetic coding
  • the image encoding apparatus performs inter prediction encoding, that is, inter prediction encoding
  • the currently encoded image needs to be decoded and stored to be used as a reference image.
  • the quantized coefficients are inversely quantized by the inverse quantizer 160 and inversely transformed by the inverse transformer 170.
  • the inverse quantized and inverse transformed coefficients are added to the prediction block through the adder 175, and a reconstructed block is calculated.
  • the reconstruction block passes through the filter unit 180, and the filter unit 180 applies at least one or more of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to the reconstruction block or the reconstruction picture. can do.
  • the reconstructed block that has passed through the filter unit 180 may be stored in the reference picture buffer 190.
  • FIG. 2 is a block diagram illustrating a configuration of an image decoding apparatus according to another embodiment of the present invention.
  • the image decoding apparatus 200 may include an entropy decoder 210, an inverse quantizer 220, an inverse transformer 230, an intra predictor 240, a motion compensator 250, and an adder ( 255, a filter unit 260, and a reference picture buffer 270.
  • the image decoding apparatus 200 may receive a bitstream output from the encoder and perform decoding in an intra mode or an inter mode, and output a reconstructed image, that is, a reconstructed image.
  • the switch In the intra mode, the switch may be switched to intra, and in the inter mode, the switch may be switched to inter.
  • the image decoding apparatus 200 may obtain a reconstructed residual block from the input bitstream, calculate a prediction block, and then add the reconstructed residual block and the prediction block to calculate a reconstructed block, that is, a reconstruction block. .
  • the entropy decoder 210 may entropy decode the input bitstream according to a probability distribution to calculate symbols including a symbol having a quantized coefficient form.
  • the entropy decoding method is similar to the entropy coding method described above.
  • the entropy decoding method When the entropy decoding method is applied, a small number of bits are allocated to a symbol having a high probability of occurrence and a large number of bits are allocated to a symbol having a low probability of occurrence, whereby the size of the bit string for each symbol is increased. Can be reduced. Therefore, the compression performance of image decoding can be improved through an entropy decoding method.
  • the quantized coefficient is inversely quantized by the inverse quantizer 220 and inversely transformed by the inverse transformer 230, and as a result of the inverse quantization / inverse transformation of the quantized coefficient, a reconstructed residual block may be calculated.
  • the intra predictor 240 may calculate a prediction block by performing spatial prediction using pixel values of blocks already decoded around the current block.
  • the motion compensator 250 may calculate a prediction block by performing motion compensation using a motion vector and a reference image stored in the reference picture buffer 270.
  • the reconstructed residual block and the prediction block may be added through the adder 255, and the added block may pass through the filter unit 260.
  • the filter unit 260 may apply at least one or more of the deblocking filter, SAO, and ALF to the reconstructed block or the reconstructed picture.
  • the filter unit 260 may output a reconstructed image, that is, a reconstructed image.
  • the reconstructed picture may be stored in the reference picture buffer 270 and used for inter prediction.
  • Methods for improving the prediction performance of the encoding / decoding apparatus include a method of increasing the accuracy of an interpolation image and a method of predicting a difference signal.
  • the difference signal is a signal representing the difference between the original image and the predicted image.
  • the "difference signal” may be used by being replaced with “difference signal”, “residual block” or “difference block” according to the context, and those skilled in the art may affect the spirit and the essence of the invention. This can be distinguished to the extent that it does not give.
  • coding unit CU
  • prediction unit PU
  • transform unit TU
  • the coding unit is an image processing unit that performs encoding / decoding, and may include information used to encode or decode the coding block and the samples of the coding block, which is a block unit set of luminance samples or chrominance samples, in which encoding / decoding is performed.
  • the prediction unit is an image processing unit that performs prediction, and may include information used to predict the prediction block and the samples of the prediction block, which is a block unit set of the luminance sample or the chrominance sample on which the prediction is performed.
  • the coding block may be divided into a plurality of prediction blocks.
  • the transformation unit may be an image processing unit that performs transformation, and may include information used to transform the transform block and the samples of the transform block, which is a block unit set of luminance samples or color difference samples.
  • the coding block may be divided into a plurality of transform blocks.
  • the current block may refer to a block in which specific image processing is performed, such as a prediction block in which current prediction is performed or a coding block in which current encoding is performed.
  • a prediction block in which current prediction is performed or a coding block in which current encoding is performed.
  • a coding block in which current encoding is performed when one coding block is divided into two prediction blocks, a block in which prediction is performed among the divided prediction blocks may be referred to as a current block.
  • the image encoding method and the image decoding method to be described later may be performed by each component included in the image encoder and the image decoder described above with reference to FIGS. 1 and 2.
  • the meaning of the component may include not only the hardware meaning but also a software processing unit that may be performed through an algorithm.
  • the deblocking method in a multiview image is not only an encoding / decoding method of the image encoding apparatus and the image decoding apparatus disclosed in FIGS. 1 and 2, but also an H.264 that is an image encoding / decoding method. It can also be used for MPEG-4 Part 10 advanced video coding (AVC).
  • AVC advanced video coding
  • FIG. 3 is a conceptual diagram illustrating a method of encoding and decoding a 3D image according to an embodiment of the present invention.
  • the transmitting side 350 uses a stereo camera 300, a depth information camera 310, a multiview camera setting 320, and a 2D video to a 3D video 330.
  • N Obtain video content at the time point.
  • the acquired image content may include N-view video information, depth-map information thereof, and camera-related additional information.
  • the video content at the time point N is compressed using a multiview video encoding method, and the compressed bitstream is transmitted to the receiver 380 through a network.
  • the receiving side decodes the received bitstream using a multiview video decoding method to reconstruct an image of N views.
  • the reconstructed N-view image generates virtual view images of at least N views by a depth-map-based rendering (DIBR) process.
  • DIBR depth-map-based rendering
  • the depth map used to generate the virtual view image represents a distance between the camera and the real object (depth information corresponding to each pixel at the same resolution as the real image) in a real number of bits in the real world.
  • FIG. 4 is a conceptual diagram illustrating a depth information map according to an embodiment of the present invention.
  • FIG. 4 (A) shows a “Champagne Tower” image being used in the 3D video coding standard of MPEG, an international standardization organization.
  • the depth information map may be image information representing, for example, 8 bits per pixel.
  • the depth information map represents the distance between the camera and the object, the correlation between pixels is very high. Especially within the object or background part, values of the same depth information appear in a wide range.
  • FIG. 5 is a conceptual diagram illustrating a depth information map according to an embodiment of the present invention.
  • 5A illustrates a depth information map of a "kendo" image.
  • FIG. 5B is a graph showing the distribution of pixel values in a horizontal position in a “kendo” image
  • FIG. 5C is a graph showing the distribution of pixel values in a vertical position in a “kendo” image.
  • the pixel value of the current block can be almost predicted using only the pixel values of the neighboring block. Therefore, the residual signal, which is a difference value between the current block and the prediction block, is not large.
  • the encoding and decoding processes for the residual block including the P are hardly necessary. Therefore, computational complexity can be reduced and coding efficiency can be improved by using intra picture coding using these characteristics.
  • the computational complexity may be reduced by not performing deblocking filtering on the background part.
  • an embodiment of the present invention discloses a method for reducing computational complexity and improving encoding efficiency in intra-picture encoding of an image having high correlation between pixels.
  • the image decoding apparatus without encoding information on the residual block, only the intra prediction mode value is encoded and transmitted to the image decoding apparatus, and the image decoding apparatus generates the prediction block generated using only the intra prediction mode value.
  • the video encoding / decoding method for outputting the R as a reconstructed block may be defined in the term of an intra skip mode. Since the residual block is not encoded in the intra skip mode, the prediction block may be generated by decoding only intra prediction information of the block without decoding the residual block in the decoding process of the intra skip mode.
  • a block encoded in an intra skip mode may be inferred to be an intra 16x16 mode (or 8x8 mode, 4x4 mode, or NxN mode) and have no difference data.
  • the information about the intra prediction mode of the block may be obtained by inferring that the intra mode (NxN prediction mode, where N is 16, 8, 4, etc.) and no difference data is referred to as an intra skip mode.
  • an intra prediction direction may be inferred from a neighboring block.
  • FIG. 6 is a conceptual diagram illustrating an intra prediction method according to an exemplary embodiment of the present invention.
  • FIG. 6 illustrates a method of predicting an intra prediction mode of a current block based on intra prediction mode information of neighboring blocks of the current block 600.
  • the intra prediction mode may include an intra prediction mode such as a vertical prediction mode (0) and a horizontal prediction mode (1) and an intra prediction mode such as a DC mode (2) and a plane mode (3). have.
  • the intra prediction mode is arbitrary and additionally, the intra prediction mode may be classified according to the direction.
  • the index value for the prediction direction may be set to have a smaller value as the probability of occurrence increases. For example, if the vertical prediction mode has the highest probability of in-screen prediction mode for a block, assign 0 as index number to the vertical prediction mode so that it is mapped to a short code word when encoding the intra prediction mode information directly. can do.
  • the occurrence probability of the intra prediction mode may vary depending on the size of the block, and thus, the indexes for the different intra prediction modes and the intra prediction modes may be mapped and used according to the size of the block.
  • IntraPredMode may be used as a variable for indicating an intra prediction mode for a block.
  • the intra prediction mode for the current block 600 may be predicted based on the intra prediction mode of the neighboring block through the following steps.
  • IntraPredModeA if block A 610 is not encoded or if the intra picture prediction mode of block A 610 is not available (e.g., block A 610 is coded in inter picture prediction mode). (Prediction mode information for block A 610) is set as the prediction mode in the DC prediction screen.
  • IntraPredModeA which is a variable representing the intra picture prediction mode of block A 610, is determined in block A 610. It can be set as an intra prediction mode value.
  • Block A 610 may have an intra prediction mode, an intra prediction mode, and an intra_skip mode as described above.
  • IntraPredModeB if block B 620 is not coded or if intra-picture prediction mode of block B 620 is not available (e.g., block B 620 is coded in inter-screen prediction mode). (Prediction mode information for block B 620) is set to the prediction mode in the DC picture.
  • IntraPredModeB which is a variable representing the intra-picture prediction mode in block B 620, is determined in block B 620. It can be set as an intra prediction mode value.
  • Block B 620 may have an intra prediction mode, an intra prediction mode, and an intra_skip mode as described above.
  • IntraPredModeA and IntraPredModeB The minimum value among IntraPredModeA and IntraPredModeB values is set as IntraPredMode of the current block (X, 600).
  • (1) and (2) is a step of deriving the intra prediction mode in block A (610) to calculate the prediction value of the intra prediction mode of the current block, the above (3) and (4)
  • a block B 620 derives the intra prediction mode.
  • the order of steps (1, 2) and (3, 4) may vary and such embodiments are also within the scope of the present invention.
  • a method other than the above method may predict the intra prediction mode for the current block.
  • IntraPredModeA is set to '-1'. If not, perform step 2. '-1' set to IntraPredModeA may be used to mean that the intra prediction mode is not derived from the block.
  • Block A 610 If block A 610 is encoded and in block A 610 can derive an intra picture prediction mode, block A 610 derives an intra picture prediction mode from IntraPredModeA to block IntraPredModeA. Sets the prediction mode value in the screen.
  • Block A 610 may have an intra prediction mode, an intra prediction mode, and an intra_skip mode as described above.
  • IntraPredModeB is set to '-1'. If not, perform step 4.
  • Block B 620 If block B 620 is encoded and in block B 620 can derive an intra picture prediction mode, block B 620 derives an intra picture prediction mode from IntraPredModeB to block IntraPredModeB. Sets the prediction mode value in the screen.
  • Block B 620 may have an intra prediction mode, an intra prediction mode, and an intra_skip mode as described above.
  • IntraPredMode of the current block 600 is set as the prediction mode in the DC picture. Otherwise, the minimum value among IntraPredModeA and IntraPredModeB values is set to IntraPredMode of the current block (X, 600).
  • An intra prediction mode value used to predict an intra prediction mode of the current block such as IntraPredModeA and IntraPredModeB, may be referred to as a candidate intra prediction mode value.
  • (1) and (2) is a step of deriving the intra prediction mode in block A (610) to calculate the prediction value of the intra prediction mode of the current block, the above (3) and (4)
  • a block B 620 derives the intra prediction mode.
  • the order of steps (1, 2) and (3, 4) may vary and such embodiments are also within the scope of the present invention.
  • the neighboring blocks used to predict the intra prediction mode value of the current block may be used in various ways. In FIG. 7, a method of predicting an intra prediction mode of a current block using three neighboring blocks will be described.
  • FIG. 7 is a conceptual diagram illustrating an intra prediction method according to an exemplary embodiment of the present invention.
  • the current block is estimated in the prediction mode for the current block 700 based on the intra prediction mode of the neighboring block through the following steps.
  • In-picture prediction mode information of the block (block C 730) as well as the block adjacent to the block (block A 710 and block B 720) may be used.
  • the intra prediction mode of block A 710 may be changed to the intra prediction mode for the current block. Can be used to set the predicted value of. Otherwise, if the intra prediction modes of the block A 710, the block B 720, and the block C 730 are all different, the intra prediction of the block A 710, the block B 720, and the block C 730 are different.
  • the intra prediction mode having the minimum value among the modes may be set as the intra prediction mode for the current block.
  • in-screen prediction modes of block A 710 and block C 730 are the same, and in-picture prediction modes of block B 720 and block C 730 are different.
  • the prediction mode may be set as a prediction value for the intra prediction mode of the current block.
  • the intra prediction mode of block A 710 when the intra prediction modes of blocks A 710 and C 730 are the same and the intra prediction modes of block B 720 and C 730 are different. May be set as a prediction value for the intra prediction mode for the current block.
  • the intra prediction modes of the blocks B 720 and C 730 are the same and the intra prediction modes of the blocks A 710 and C 730 are different, the intra prediction modes of the block A 710 are different.
  • the intra prediction mode of the block B 720 is changed to the current block. It can be set as the prediction value of the intra prediction mode for.
  • the intra prediction modes of blocks A 710, B 720, and C 730 may be referred to as candidate intra prediction modes for predicting the intra prediction modes of the current block.
  • the intra prediction mode of the current block may be set by comparing the identity.
  • the intrablock prediction of the current block is not immediately determined without determining the prediction value of the intrablock prediction mode of the current block in consideration of whether the neighboring block is performing intra prediction, encoding, and intra prediction information. It is also possible to predict the mode and such embodiments are also within the scope of the present invention.
  • the method of configuring the intra prediction image may be variously applied.
  • the pixel of the neighboring block adjacent to the current block may be copied (padded) as it is, wherein the pixel to be copied (padded) to the current block is a pixel located above the neighboring block adjacent to the current block or Alternatively, the pixel may be located on the left side, or may be an average or weighted average of pixels adjacent to the current block.
  • the reference pixel used to generate the prediction block by performing the intra prediction according to the intra prediction mode may be different.
  • information about which pixel to use may be encoded and included in the bitstream.
  • a pixel to be used as a prediction pixel of the current block may be determined by considering characteristics of neighboring pixels adjacent to the current block, and then the prediction block of the current block may be generated through the determined pixel.
  • the prediction block for the current block may be generated based on the upper pixel adjacent to the current block. have.
  • the prediction block for the current block may be generated through the pixels on the left adjacent to the current block.
  • a prediction block image may be configured by using a plurality of prediction methods and mixing the average value or the sum of weights according to each method.
  • the method of configuring the intra prediction block as described above may be variously changed.
  • a prediction block for a current block is generated by taking a block most similar to a current block from a previous frame that has been previously encoded and then decoded.
  • the generated prediction block image is differentiated from the current block image to generate a differential block image.
  • the encoding is performed in two ways depending on whether a transform, quantization, and entropy encoding process is performed on the differential block image, and information on whether encoding is performed on the differential block image is included in the bitstream.
  • the current block image is transformed and quantized into a block image that is differential from the predicted block image, and is then entropy encoded to output a bitstream, and inverse quantization of the quantized coefficients before entropy encoding is performed. After inverse transformation, the prediction block image is added, and the current block image is reconstructed.
  • the current block image is composed of only prediction block images.
  • the differential block image is not encoded, and only information on whether encoding is performed on the differential block image is included in the bitstream.
  • arithmetic encoding may be performed probabilisticly in consideration of whether to encode the residual block or not by encoding information on neighboring blocks of the current block.
  • a method of constructing the current block using only intra-prediction blocks may be defined as an intra skip mode, and a block encoded in the intra skip mode may have a high correlation between the current block and a neighboring block. . Therefore, in this case, even if the deblocking filtering is not performed, there may not be a step of the image.
  • an embodiment of the present invention discloses a method of determining the boundary filtering strength (bS) of the deblocking filtering in the intra skip mode.
  • FIG. 8 is a conceptual diagram illustrating a method of determining boundary filtering strength (bS) of deblocking filtering according to an embodiment of the present invention.
  • step S800 in order to determine boundary strength (bS), first, encoding modes of blocks p and block q adjacent to each other are checked (step S800).
  • whether the block p or the block q is intra coded or inter coded may mean that the block p or the block q is or belongs to an intra coded block.
  • FIG. 9 is a conceptual diagram illustrating a boundary between blocks according to an embodiment of the present invention.
  • blocks p (900, 920) represent blocks located on the left side 900 or upper 920 with respect to the block boundary
  • blocks q (910, 930) represent the right side 910 with respect to the block boundary. Or a block located at the bottom 930.
  • At least one of blocks p 900 and q 910 adjacent to each other may be intra skip mode. It can be determined whether or not is encoded. In the following embodiments of the present invention, for convenience of description, only the blocks p 900 and q 910 will be described.
  • the boundary filtering strength bS is determined to be '0' (step S810).
  • the strength of filtering may be expressed as an integer value. For example, it may mean that stronger filtering is performed from 0 to 4 with an edge value of 0-4.
  • the integer value indicative of the boundary filtering strength may vary as arbitrary.
  • step S820 when one or more blocks encoded using the intra prediction method among the blocks p 900 and q 910 exist, the process proceeds to the 'INTRA MODE' step (step S823).
  • step S823 When both the block p 900 and the block q 910 are inter coded, the process may proceed to the 'INTER MODE' step (step S825).
  • step S820 when it is determined that at least one intra-encoded block exists among the blocks p 900 and q 910, the boundary between the blocks p 900 and block q 910 is a macro block. It may be determined whether or not to match the boundary of (step S830).
  • step S830 when the boundary between the block p 900 and the block q 910 coincides with the boundary of the macroblock, the boundary filtering strength bS is determined to be 4 (step S840). On the other hand, if the boundary between the block p 900 and the block q 910 is not the boundary of the macroblock MB, the boundary filtering strength bS is determined to be 3 (step S850).
  • the boundary filtering strength bS is 4, the strongest filtering is applied in the subsequent filtering application procedure, and the smaller the value of the boundary filtering strength is, the weaker the filtering strength is. Determining whether the boundary between the blocks used in the embodiment of the present invention is a macroblock is because the step between the blocks may become larger as the boundary of the macroblock increases the strength of filtering by determining whether the boundary between the blocks is a macroblock. Can be determined.
  • Determining whether the boundary between blocks is a macroblock is an example of determining what boundary character the boundary between blocks has, and the characteristics of the boundary between blocks can be determined based on other criteria. Also included in the scope of the present invention. In other words, the filtering strength may be applied differently even when the blocks are different boundary values of the partition.
  • step S820 when it is determined that both the block p 900 and the block q 910 are both predicted blocks using the inter prediction, at least one of the blocks p 900 and the block q 910 is determined. It is determined whether one block has a non-zero transform coefficient (step S860).
  • Orthogonal transform coefficients are also referred to as coded coefficients or non-zero transformed coefficients.
  • the boundary filtering strength bS is determined to be 2 (step S870). Otherwise, the flow proceeds to the next step S880.
  • step S880 whether the absolute value of the difference between one component of the motion vector, that is, the x-axis component or the y-axis component, is greater than or equal to 1 (or 4) with respect to the block p 900 and the block q 910. It is determined whether the reference frame in the compensation is different and / or the PU partition boundary.
  • the reference frame is different' may include both the reference frame itself is different and the number of reference frames is different.
  • step S880 when at least one of the absolute values of the difference of the motion vectors becomes 1 (or 4) or more, or when the reference frame in motion compensation is different, the boundary filtering intensity bS is determined to be 1 (step S890). ). On the other hand, when the absolute values of the differences of the motion vectors are all less than 1 (or 4) and the reference frames in the motion compensation are the same, the boundary filtering intensity bS is determined to be 0 (step S810).
  • a boundary filtering strength bS of zero may indicate that no filtering is performed in a subsequent filtering application procedure.
  • the determination of the boundary filtering strength bS when encoded in the intra skip mode, may be variously applied as follows.
  • the boundary filtering strength between the current block and the neighboring block may be set to '0'.
  • the filtering strength between the current block and the neighboring block may be set by determining whether the intra prediction modes of the current block and the neighboring block are both intra skip mode.
  • the boundary filtering strength between the current block and the neighboring block may be set to '0'.
  • One of the current block and neighboring blocks is a block coded using intra skip mode, and the other block is a code coded using a general intra picture prediction mode or a code coded using an inter picture prediction mode. Can be.
  • the boundary filtering strength between the current block and the neighboring block can be set to '4', otherwise the filtering strength is set to '0'.
  • the boundary filtering strength can be set differently according to the existence of orthogonal transform coefficients.
  • the boundary filtering intensity is set to '0' and the other case is different.
  • the filtering strength is adaptively adjusted according to the intra prediction mode used when using the intra skip mode of the neighboring block and the current block. Can be changed.
  • FIG. 10 is a conceptual diagram illustrating a method of adaptively changing a filtering strength according to an intra prediction mode used when using an intra skip mode according to an embodiment of the present invention.
  • the filtering strength of the deblocking when the filtering strength of the deblocking is set for the macroblock boundary in the vertical direction of the current block (X, 1010), the prediction direction of the neighboring blocks (A, 1000) and the current block (X, 1010) are set. ), The intra-prediction mode is the same, so the filtering strength of the deblocking can be set to '0'. Even when the macroblock boundary in the horizontal direction of the current block (X, 1030) and the neighboring blocks (B, 1020) is the same in intra prediction mode of the current block (X, 1030) and the neighboring blocks (B, 1020), the deblocking The filtering strength can be set to '0'.
  • various methods may be used to determine the boundary filtering strength bS.
  • FIG. 11 is a block diagram illustrating a case where an intra prediction method is performed in an intra skip mode according to an embodiment of the present invention.
  • a bitstream is received and decoded to output a reconstructed image.
  • the entropy decoder 1100 first decodes encoding information of differential block image information of a current block image in a bitstream.
  • the decoding of the encoding information may be performed arithmetic decoding probabilisticly through the encoding information of the neighboring blocks of the current block.
  • the current block image outputs a quantized coefficient by performing variable length decoding according to a probability distribution.
  • the quantized coefficients are subjected to an inverse quantization process and an inverse transform process to output a difference block image, and the difference block image is added to the prediction block image that performs intra prediction to generate a reconstructed current block image.
  • the intra block mode does not include differential block image information on the current block image, whether the current block image is restored to the block on which the intra prediction is performed or the image is restored to the block on which the inter prediction is performed. Information is decoded and output to the prediction method decision process 1120.
  • the image is reconstructed by performing image prediction according to the decoded information to configure a current block image.
  • the reconstructed current block image may be stored in the reference image buffer and later output.
  • the macroblock layer (macroblock_layer) syntax is shown in Table 1 below. Can be modified to implement
  • mb_intra_skip_run and “mb_intra_skip_flag” may mean that the current depth information map block is composed of only prediction images.
  • the fact that the current depth map block is composed of only the prediction image may be interpreted as that the current block is a block encoded using an intra skip mode. It can also be interpreted that there is no difference data while in the intra mode (NxN prediction mode where N is 16, 8, 4, etc.).
  • Mb_intra_skip_run means that the entropy coding method operates in context-based adaptive variable length coding (CAVLC)
  • mb_intra_skip_flag means that the entropy coding method operates in context-based adaptive arithmetic coding CABAC.
  • an example of actually implementing the intra skip method according to an embodiment of the present invention in H.264 / AVC, which is an international video standard, is performed when both intra coding and inter screen encoding are performed (I or P or B frame). Case) can be implemented by modifying the macroblock layer (macroblock_layer) syntax as shown in Table 2 below.
  • “Mb_intra_skip_flag” means that the current depth information map block is composed of only prediction images. If mb_intra_skip_flag ”is '1', the differential block data is not parsed. Otherwise, when mb_intra_skip_flag ”is '0', differential block data is parsed according to the conventional method. In this case, the fact that the data of the difference block is not parsed may be interpreted as an intra skip mode, and may also be interpreted as an intra mode (NxN prediction mode where N is 16, 8, 4, etc.) and no difference data. Can be.
  • FIG. 12 is a block diagram illustrating a method of configuring a current block image using only prediction blocks using neighboring blocks when in-screen encoding of an image having high correlation between pixels according to an embodiment of the present invention.
  • the prediction image generator 1200 generates a prediction block through an intra prediction process or a prediction block through an inter prediction process.
  • the detailed generation method is as described above.
  • the predictive image selector 1210 selects the most excellent coding efficiency among the predictive images generated by the predictive image generator 1200, and the predictive image selection information is included in the bitstream.
  • the subtractor 1220 generates a differential block image by subtracting the current block image from the predicted block image.
  • the encoding determination unit 1230 determines whether to encode the difference block image, and outputs encoding information.
  • the encoder 1240 determines whether to perform the encoding according to the encoding information determined by the encoding determiner 1230, and outputs a compressed bitstream after the transform, quantization, and entropy encoding processes are performed on the differential block image.
  • the encoder may not separately encode pixel information of the difference block.
  • the bitstream of the compressed differential block image output from the encoder 1240 the bitstream of the compressed differential block image output from the encoder 1240, the encoding status information output from the encoding determination unit 1230, and the prediction image output from the prediction image selector 1210.
  • One bitstream is output by mixing the selection information.
  • FIG. 13 is a block diagram illustrating a method of configuring a current block image using only prediction blocks using neighboring blocks when in-screen encoding of an image having high correlation between pixels according to an embodiment of the present invention.
  • the demultiplexer 1300 decodes whether information about a differential image is included in a bitstream and whether predictive image selection information is included in the bitstream.
  • the decryption determination unit 1310 determines whether to perform decryption according to the decryption information.
  • the decoder 1320 is performed only when there is information on the difference image in the bitstream according to the decoding information.
  • the decoder 1320 reconstructs the differential image through inverse quantization and inverse transformation.
  • the predictive image generator 1350 generates a prediction block through an intra prediction process or generates a prediction block through an inter prediction process.
  • the predicted image determiner 1340 determines an optimal predicted image of the current block from the predicted images generated by the predicted image generator 1350 through the predicted image selection information.
  • the adder 1330 adds the generated prediction image and the reconstructed difference image to form a reconstructed image. At this time, if the reconstructed difference image does not exist, the predictive image is composed of the reconstructed image.

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