EP4635172A1 - Appareil de génération d'image de prédiction, appareil de décodage vidéo, appareil de codage vidéo et procédé de génération d'image de prédiction - Google Patents

Appareil de génération d'image de prédiction, appareil de décodage vidéo, appareil de codage vidéo et procédé de génération d'image de prédiction

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Publication number
EP4635172A1
EP4635172A1 EP23903207.1A EP23903207A EP4635172A1 EP 4635172 A1 EP4635172 A1 EP 4635172A1 EP 23903207 A EP23903207 A EP 23903207A EP 4635172 A1 EP4635172 A1 EP 4635172A1
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EP
European Patent Office
Prior art keywords
prediction
mode
unit
filter
dimd
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
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EP23903207.1A
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German (de)
English (en)
Inventor
Zheming FAN
Tomohiro Ikai
Yukinobu Yasugi
Tomoko Aono
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Sharp Corp
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Sharp Corp
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Publication date
Priority claimed from JP2022201548A external-priority patent/JP2025160931A/ja
Application filed by Sharp Corp filed Critical Sharp Corp
Publication of EP4635172A1 publication Critical patent/EP4635172A1/fr
Pending legal-status Critical Current

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Classifications

    • 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
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/103—Selection of coding mode or of prediction mode
    • H04N19/11—Selection of coding mode or of prediction mode among a plurality of spatial predictive coding modes
    • 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
    • H04N19/593—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial prediction techniques
    • 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
    • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards
    • 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
    • H04N19/80—Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation

Definitions

  • the embodiments of the present invention relate to a prediction image generation apparatus, a video decoding apparatus, a video coding apparatus, and a prediction image generation method.
  • a video coding apparatus which generates coded data by coding a video
  • a video decoding apparatus which generates decoded images by decoding the coded data are used for efficient transmission or recording of videos.
  • specific video coding schemes include H.264/AVC, High-Efficiency Video Coding (HEVC), and Versatile Video Coding (VVC) schemes, and the like.
  • images (pictures) constituting a video are managed in a hierarchical structure including slices obtained by splitting an image, coding tree units (CTUs) obtained by splitting a slice, units of coding (coding units; which will be referred to as CUs) obtained by splitting a coding tree unit, and transform units (TUs) obtained by splitting a coding unit, and are coded/decoded for each CU.
  • CTUs coding tree units
  • coding units coding units; which will be referred to as CUs
  • transform units (TUs) obtained by splitting a coding unit
  • a prediction image is generated based on a local decoded image that is obtained by coding/decoding an input image (a source image), and prediction error components (which may be referred to also as “difference images” or “residual images”) obtained by subtracting the prediction image from the input image are coded.
  • prediction images which may be referred to also as “difference images” or “residual images” obtained by subtracting the prediction image from the input image are coded.
  • Generation methods of prediction images include an inter-picture prediction (an inter-prediction) and an intra-picture prediction (intra prediction).
  • NPL1 Decoder-side Intra Mode Derivation (DIMD) prediction method
  • the decoder derives the prediction image by deriving the intra angular prediction mode using pixels in adjacent regions for luma prediction.
  • NPL2 proposes a improvement on DIMD method, in which using different reference region for predicting.
  • NPL3 proposes method using DIMD method for chroma prediction.
  • NPL 1 M. Abdoli, T. Guionnet, E. Mora, et. al, “Non-CE3: Decoder-side Intra Mode Derivation with Prediction Fusion Using Planar”, JVET-O0449, Gothenburg, July 2019.
  • NPL 2 Z. Fan, Y. YASUGI, T. IKAI, “Non-EE2:Adaptive reference region DIMD”, JVET-AB0065, Mainz, DE, 20-28 October 2022
  • NPL 3 X. Li, R. Liao, J, Chen, Y. Ye, “Non-EE2: On chroma intra prediction mode,” JVET-Y0092, Teleconference, 12-21 January 2022.
  • the intra mode is derived on the decoder side using the gradient of pixel values in different neighboring regions. But in NPL2, there is a problem that the prediction angle of neighboring blocks may not be consistent with the prediction angle of target block. And the size and the value of the derivation filter used in NPL1 and NPL3 are fixed and this is not the best choosing for some situations.
  • This invention aims at improving the accuracy by deriving different filters and switching the filters which are used for calculating gradients in accordance with the size of target block in the decoder side intra mode derivation.
  • the adaptive reference region DIMD (NPL2) method allows the selection of reference regions with three patterns: 1: using top-left, top, and left neighboring regions. 2: using top-left, top, and top-right neighboring regions. 3: using top-left, left, and left-bottom neighboring regions. named DIMD_TL, DIMD_T, and DIMD_L, respectively.
  • the DIMD (NPL1) and DIMD CHROMA (NPL3) method derive the intra prediction direction by using the gradient of pixel values in different neighboring regions for luma and chroma prediction, respectively.
  • a filter selection unit 3104611 is included in a gradient derivation unit 310461.
  • the filter selection unit 3104611 chooses filter based on the sizeof target block.
  • the filter selection unit 3104611 is characterized by using different filter for the target block with different size.
  • the amount of calculation for intra prediction mode derivation can be reduced while limitting a coding loss and the quality of the codecs can be improved without adding additional calculations.
  • FIG. 1 is a schematic diagram illustrating a configuration of an image transmission system according to the present embodiment.
  • FIG. 2 is a diagram showing the hierarchical structure of the coded stream data.
  • FIG. 3 is a schematic diagram showing the type of intra-prediction mode (mode number).
  • FIG. 4 is a schematic diagram of the video decoder.
  • FIG. 5 is an example of DIMD syntax.
  • FIG. 6 is a figure of the binaryization of the dimd_mode syntax used in the DIMD prediction unit 31046.
  • FIG. 7 is another example of DIMD syntax.
  • FIG. 8 shows the structure of the intra prediction image generation unit 310.
  • FIG. 9 is a diagram showing the details of the DIMD prediction unit 31046.
  • FIG. 10 shows an example of the reference region referred to by the DIMD prediction unit 31046.
  • FIG. 10 shows an example of the reference region referred to by the DIMD prediction unit 31046.
  • FIG. 11 shows an example of a set of spatial filters.
  • FIG. 12 shows an example of a target pixel for gradient derivation when using 3x3 filter.
  • FIG. 13 shows example of a target pixel for gradient derivation when using 2x2 filter.
  • FIG. 14 shows examples of a target pixel for gradient derivation when using 2x2 filter.
  • FIG. 15 is a block diagram illustrating the relationship between the gradient and the region.
  • FIG. 16 is a block diagram showing the structure of the angle derivation unit.
  • FIG. 17 shows examples of the reference region used for gradient derivation of the DIMD prediction unit 31046.
  • FIG. 18 is a block diagram showing an example of the configuration of the inverse quantization and inverse transform processing unit 311.
  • FIG. 19 is a block diagram showing the structure of a video coding system.
  • FIG. 20 is a diagram showing the details of the DIMD CHROMA prediction unit 31047.
  • FIG. 21 shows an example of the reference region referred to by the DIMD prediction unit 31046.
  • FIG. 22 shows some examples of the filter used for gradient derivation.
  • FIG. 23 shows some examples of the filter used for gradient derivation.
  • FIG. 24 shows examples of gradient derivation pixels for gradient derivation when using filter.
  • FIG. 25 shows examples of gradient derivation pixels for gradient derivation when using filter.
  • FIG. 26 shows an example of the reference region used for gradient derivation of the DIMD prediction unit 31046.
  • FIG. 27 is a block diagram showing the structure of the angular mode derivation device 310475.
  • FIG. 28 shows examples of the reference region used for gradient derivation of the DIMD CHROMA prediction unit 31047.
  • FIG. 1 is a schematic diagram illustrating a configuration of an image transmission system 1 according to the present embodiment.
  • the image transmission system 1 is a system in which a coding stream obtained by coding a coding target image is transmitted, the transmitted coding stream is decoded, and an image is displayed.
  • the image transmission system 1 includes a video coding apparatus (image coding apparatus) 11, a network 21, a video decoding apparatus (image decoding apparatus) 31, and a video display apparatus (image display apparatus) 41.
  • An image T is input to the video coding apparatus 11.
  • the network 21 transmits a coding stream Te generated by the video coding apparatus 11 to the video decoding apparatus 31.
  • the network 21 is the Internet, a Wide Area Network (WAN), a Local Area Network (LAN), or a combination thereof.
  • the network 21 is not necessarily limited to a bidirectional communication network, and may be a unidirectional communication network configured to transmit broadcast waves of digital terrestrial television broadcasting, satellite broadcasting or the like.
  • the network 21 may be substituted by a storage medium in which the coding stream Te is recorded, such as a Digital Versatile Disc (DVD: trademark) or a Blu-ray Disc (BD: trademark).
  • DVD Digital Versatile Disc
  • BD Blu-ray Disc
  • the video decoding apparatus 31 decodes each of the coding streams Te transmitted from the network 21 and generates one or multiple decoded images Td which are decoded.
  • the video display apparatus 41 displays all or part of the one or multiple decoded images Td generated by the video decoding apparatus 31.
  • the video display apparatus 41 includes a display device such as a liquid crystal display and an organic Electro-Luminescence (EL) display. Forms of the display include a stationary type, a mobile type, an HMD type, and the like.
  • a display device such as a liquid crystal display and an organic Electro-Luminescence (EL) display.
  • EL Organic Electro-Luminescence
  • x ? y : z is a ternary operator to take y in a case that x is true (other than 0) and take z in a case that x is false (0).
  • abs(a) is a function that returns the absolute value of a.
  • Int(a) is a function that returns the integer value of a.
  • floor(a) is a function that returns the maximum integer equal to or less than a.
  • ceil(a) is a function that returns the minimum integer equal to or greater than a.
  • a/d represents division of a by d (round down decimal places).
  • FIG. 4 is a diagram illustrating a hierarchical structure of data of the coding stream Te.
  • the coding stream Te includes a sequence and multiple pictures constituting the sequence illustratively.
  • (a) to (f) of FIG. 4 are diagrams illustrating a coded video sequence defining a sequence SEQ, a coded picture prescribing a picture PICT, a coding slice prescribing a slice S, a coding slice data prescribing slice data, a coding tree unit included in the coding slice data, and a coding unit (CU) included in each coding tree unit, respectively.
  • the coded video sequence includes a Video Parameter Set (VPS), a Sequence Parameter Set (SPS), a Picture Parameter Set (PPS), a picture (PICT), and Supplemental Enhancement Information (SEI).
  • VPS Video Parameter Set
  • SPS Sequence Parameter Set
  • PPS Picture Parameter Set
  • PICT picture
  • SEI Supplemental Enhancement Information
  • a set of coding parameters common to multiple videos and a set of coding parameters associated with the multiple layers and an individual layer included in the video are defined.
  • sequence parameter set SPS a set of coding parameters referred to by the video decoding apparatus 31 to decode a target sequence is defined. For example, a width and a height of a picture are defined. Note that multiple SPSs may exist. In that case, any of multiple SPSs is selected from the PPS.
  • a set of coding parameters referred to by the video decoding apparatus 31 to decode each picture in a target sequence is defined.
  • a reference value (pic_init_qp_minus26) of a quantization step size used for decoding of a picture and a flag (weighted_pred_flag) indicatingan application of a weighted prediction are included.
  • multiple PPSs may exist. In that case, any of multiple PPSs is selected from each picture in a target sequence.
  • the picture PICT includes a slice 0 to a slice NS-1 (NS is the total number of slices included in the picture PICT).
  • the coding slice a set of data referred to by the video decoding apparatus 31 to decode the slice S to be processed is defined. As illustrated in FIG. 2, the slice includes a slice header and a slice data.
  • the slice header includes a coding parameter group referred to by the video decoding apparatus 31 to determine a decoding method for a target slice.
  • Slice type specification information (slice_type) indicating a slice type is one example of a coding parameter included in the slice header.
  • Examples of slice types that may be specified by the slice type specification information include (1) I slice using only an intra prediction in coding, (2) P slice using a unidirectional prediction or an intra prediction in coding, and (3) B slice using a unidirectional prediction, a bidirectional prediction, or an intra prediction in coding, and the like.
  • the inter prediction is not limited to a uni-prediction and a bi-prediction, and the prediction image may be generated by using a larger number of reference pictures.
  • the slice indicates a slice that includes a block in which the inter prediction may be used.
  • the slice header may include a reference to the picture parameter set PPS (pic_parameter_set_id).
  • the coding slice data a set of data referred to by the video decoding apparatus 31 to decode the slice data to be processed is defined.
  • the slice data include CTUs as illustrated in FIG. 2.
  • the CTU is a block of a fixed size (for example, 64 x 64) constituting a slice, and may be called a Largest Coding Unit (LCU).
  • LCU Largest Coding Unit
  • Coding Tree Unit a set of data referred to by the video decoding apparatus 31 to decode the CTU to be processed is defined.
  • the CTU is split into coding units CUs, each of which is a basic unit of coding processing, by a recursive Quad Tree split (QT split), Binary Tree split (BT split), or Ternary Tree split (TT split).
  • QT split recursive Quad Tree split
  • BT split Binary Tree split
  • TT split Ternary Tree split
  • the BT split and the TT split are collectively referred to as a Multi Tree split (MT split).
  • Nodes of a tree structure obtained by recursive quad tree splits are referred to as Coding Nodes.
  • Intermediate nodes of a quad tree, a binary tree, and a ternary tree are coding nodes, and the CTU itself is also defined as the highest coding node.
  • the CU includes a CU header CUH, a prediction parameter, a transform parameter, a quantization transform coefficient, and the like.
  • a prediction mode and the like are defined in the CU header.
  • the prediction processing is performed in units of CU or performed in units of sub-CU obtained by further splitting the CU.
  • the sizes of the CU and the sub-CU are equal to each other, the number of sub-CUs in the CU is one.
  • the CU is split into sub-CUs. For example, in a case that the CU has a size of 8 x 8, and the sub-CU has a size of 4 x 4, the CU is split into four sub-CUs which include two horizontal splits and two vertical splits.
  • prediction modes There are two types of predictions (prediction modes), which are an intra prediction and an inter prediction.
  • the intra prediction refers to a prediction in an identical picture
  • the inter prediction refers to prediction processing performed between different pictures (for example, between pictures of different display times).
  • Transform and quantization processing is performed in units of CU, but the quantization transform coefficient may be subjected to entropy coding in units of subblock such as 4 x 4.
  • Prediction parameter A prediction image is derived by a prediction parameter accompanying a block.
  • the prediction parameter includes prediction parameters of the intra prediction and the inter prediction.
  • the intra prediction parameter includes a luma intra prediction mode IntraPredModeY and a chroma prediction mode IntraPredModeC.
  • FIG. 3 is a schematic diagram indicating types (mode numbers) of the intra prediction mode. As illustrated in the diagram, for example, there are 67 types (0 to 66) of intra prediction modes. For example, a planar prediction (0), a DC prediction (1), and Angular predictions (2 to 66) are present. Furthermore, for chroma, CCLM (Cross Component Linear Model) prediction mode (81 to 83),MMLM (Multi Mode Linear Model) prediction mode, and LM (Linear Model) prediction modemay be added.
  • CCLM Cross Component Linear Model
  • MMLM Multi Mode Linear Model
  • LM Linear Model
  • Configuration of video decoding apparatus A configuration of the video decoding apparatus 31 (FIG. 4) according to the present embodiment will be described.
  • the video decoding apparatus 31 includes an entropy decoding unit 301, a parameter decoding unit (prediction image decoding apparatus) 302, a loop filter 305, a reference picture memory 306, a prediction parameter memory 307, a prediction image generation unit 308, an inverse quantization and inverse transform processing unit 311, an addition unit 312, and a prediction parameter derivation unit 320. Note that a configuration in which the loop filter 305 is not included in the video decoding apparatus 31 is also used in accordance with the video coding apparatus 11 described later.
  • the parameter decoding unit 302 further includes a header decoding unit 3020, a CT information decoding unit 3021, and a CU decoding unit 3022 (prediction mode decoding unit), and the CU decoding unit 3022 further includes a TU decoding unit 3024. These may be collectively referred to as a decoding module.
  • the header decoding unit 3020 decodes, from coded data, parameter set information such as the VPS, the SPS, and the PPS, and a slice header (slice information).
  • the CT information decoding unit 3021 decodes a CT from coded data.
  • the CU decoding unit 3022 decodes a CU from coded data.
  • the TU decoding unit 3024 decodes QP update information (quantization correction value) and a quantization prediction error (residual_coding) from coded data.
  • the entropy decoding unit 301 performs entropy decoding on the coding stream Te input from the outside and separates and decodes individual codes (syntax elements).
  • the separated codes include prediction information to generate a prediction image, a prediction error to generate a difference image, and the like.
  • Entropy coding has a variable length coding method for syntax elements according to the context (probability model) adaptively selected according to the type of syntax elements and the surrounding conditions, and a variable length coding method for syntax elements using a predetermined table or formula.
  • dimd_mode is a parameter for selecting the reference region of DIMD method.
  • the dimd_mode includes DIMD_MODE_TOP_LEFT mode, DIMD_MODE_TOP mode, and DIMD_MODE_LEFT mode. This three modes are represented by 0,1,2 respectively.
  • FIG.6 shows an example of binarization of dimd_mode.
  • Bin0 is a flag used for indicating if the DIMD_MODE_TOP_LEFT is selected. When Bin0 is 0, the DIMD_MODE_TOP_LEFT mode will be selected, and when Bin0 is 1, the DIMD_MODE_TOP_LEFT mode will not be selected.
  • Bin1 is a flag used for indicating which one of DIMD_MODE_TOP mode and DIMD_MODE_LEFT mode is selected. When Bin1 is 0, DIMD_MODE_TOP mode will be selected, and when Bin1 is 1, the DIMD_MODE_LEFT mode will be selected.
  • Bin0 and Bin1 are not used to form one syntax element, but to assign a syntax element to Bin0 and Bin1 respectively.
  • dimd_mode can perspective two syntax elements.
  • the syntax element assigned to Bin0 is named dimd_ mode_ flag
  • the syntax element assigned to Bin1 is named dimd_ mode_ dir (shown in Fig.7).
  • the entropy decoding unit 301 can get the dimd_mode from dimd_mode_flag and dimd_mode_dir by the following formula. And when dimd_ mode_ flag is 0, dimd_ mode_ dir will be set to 0, too.
  • DIMD_MODE_TOP_LEFT is represented by 1 bit (such as "0"), and 1 bit is allocated after "0" to represent DIMD_MODE_TOP and DIMD_MODE_LEFT.
  • using a bits which is shorter than the selection of DIMD_MODE_TOP and DIMD_MODE_LEFT mode using a bits which is shorter than the selection of DIMD_MODE_TOP and DIMD_MODE_LEFT mode. This can shorten the average coding amount to improve the coding efficiency.
  • the parameter decoding unit 302 notifies the entropy decoding unit 301 of which syntax elements need be decoded.
  • the entropy decoding unit 301 outputs the syntax element to the prediction parameter derivation unit 320.
  • the prediction parameter derivation unit 320 may derive the prediction parameters based on the output of the paremater decoding unit 302 and the prediction parematers which saved in the prediction parameter memory 307. The derived prediction parameters will be output into the prediction image generation unit 308 and also will be saved in the prediction parameter memory 307. The prediction parameter derivetion unit 320 may derive different prediction mode for the Luma and Chroma prediction.
  • the loop filter 305 is a filter provided in the coding loop, and is a filter that removes block distortion and ringing distortion and improves image quality.
  • the loop filter 305 applies a filter such as a deblocking filter, a Sample Adaptive Offset (SAO), and an Adaptive Loop Filter (ALF) on a decoded image of a CU generated by the addition unit 312.
  • a filter such as a deblocking filter, a Sample Adaptive Offset (SAO), and an Adaptive Loop Filter (ALF) on a decoded image of a CU generated by the addition unit 312.
  • the reference picture memory 306 stores the decoded image of the CU generated by the addition unit 312 in a predetermined position for each target picture and target CU.
  • the prediction parameter memory 307 stores prediction parameters in a predetermined position for each CTU or CU to be decoded. Specifically, the prediction parameter memory 307 stores a parameter derived by the prediction parameter derivation unit 320, a prediction mode predMode separated by the entropy decoding unit 301, and the like.
  • the prediction image generation unit 308 receives input of the prediction parameter derived by the prediction parameter deviation unit 320, and the like. In addition, the prediction image generation unit 308 reads a reference picture from the reference picture memory 306. The prediction image generation unit 308 generates a prediction image of a block or a subblock by using the prediction parameter and the read reference picture (reference picture block) in the prediction mode indicated by the prediction mode predMode.
  • the reference picture block refers to a set of pixels (referred to as a block because they are normally rectangular) on a reference picture and is a region that is referred to to generate a prediction image.
  • the intra prediction image generation unit 310 performs an intra prediction by using an intra prediction parameter (luma intra prediction mode IntraPredModeY and/or chroma intra prediction mode IntraPredModeC) input from the prediction parameter derivation unit 320 and reference pixels read from the reference picture memory 306.
  • the prediction mode predMode indicates an inter prediction mode
  • the inter prediction image generation unit performs an inter prediction by using an inter prediction parameter input from the prediction parameter derivation unit 320 and reference pixels read from the reference picture memory 306.
  • the prediction image generation unit 308 reads, from the reference picture memory 306, a neighbouring block in a predetermined range from a target block on a target picture.
  • the predetermined range is neighbouring blocks on the left, the top left, the top, and the top right of the target block, and the region referred to is different depending on the intra prediction mode.
  • the prediction image generation unit 308 generates a prediction image of the target block with reference to the read decoded pixel values and the prediction mode indicated by predMode, IntraPredModeY and/or IntraPredModeC.
  • the prediction image generation unit 308 outputs the generated prediction image of the block to the addition unit 312.
  • a decoded peripheral region adjacent to (proximate to) the prediction target block is configured as a reference region R. Then, the pixels on the reference region R are extrapolated in a specific direction to generate the prediction image.
  • the reference region R may be configured as an L-shaped region including the left and top (or further, top left, top right, bottom left) of the prediction target block.
  • Intra prediction image generation unit 310 A configuration of the intra prediction image generation unit 310 will be described using FIG. 8.
  • the intra prediction image generation unit 310 includes a reference sample filterunit 3103 (second reference image configuration unit), an intra prediction unit 3104), and a prediction image corrector 3105 (prediction image corrector, filter switching unit, weight coefficient changing unit).
  • the intra prediction unit 3104 Based on each reference pixel (unfiltered reference image) on the reference region R, a filtered reference image generated by applying a reference pixel filter (first filter), and the intra prediction mode, the intra prediction unit 3104 generates a prediction image of the target block, and outputs the generated image to the prediction image corrector 3105.
  • the prediction image corrector 3105 corrects the prediction image in accordance with the intra prediction mode, and outputs a corrected prediction image.
  • the units included in the intra prediction image generation unit 310 will be described.
  • Reference sample filterunit 3103 applies the reference pixel filter (first filter) to the unfiltered reference image to derive a filtered reference image s[x][y] at each position (x, y) on the reference region R, in accordance with the intra prediction mode. Specifically, a low pass filter is applied to the unfiltered reference image at each position (x, y) and its surroundings, and a filtered reference image is derived. Note that the low pass filter need not necessarily be applied in all the intra prediction modes, and the low pass filter may be applied in some intra prediction modes.
  • the filter applied to an unfiltered reference image on a reference region R in the reference sample filterunit 3103 is referred to as the “reference pixel filter (first filter)”, whereas a filter that corrects the prediction image in the prediction image corrector 3105 described below is referred to as a “boundary filter (second filter)”.
  • the intra prediction unit 3104 generates, based on the intra prediction mode, the unfiltered reference image, and the filtered reference pixel value, a prediction image (prediction pixel value, uncorrected prediction image) of the prediction target block, and outputs a generated image to the prediction image corrector 3105.
  • the intra prediction unit 3104 includes a Planar prediction unit 31041, a DC prediction unit 31042, an Angular prediction unit 31043, an LM prediction unit 31044, an MIP prediction unit (Matrix-based Intra Prediction) 31045, a DIMD (Decoder-side Intra Mode Derivation, DIMD) prediction unit 31046, and a DIMD CHROMA prediction unit 31047 in the inside thereof.
  • the intra prediction unit 3104 selects a specific predictor in accordance with the intra prediction mode, and inputs an unfiltered reference image and a filtered reference image thereto.
  • the relationship between the intra prediction mode and the corresponding predictor is as follows. - Planar prediction ... Planar prediction unit 31041 - DC prediction ... DC prediction unit 31042 - Angular prediction ... Angular prediction unit 31043 - LM prediction ... LM prediction unit 31044 - MIP prediction ... MIP prediction unit 31045 - DIMD prediction ... DIMD prediction unit 31046 - DIMD CHROMA prediction ... DIMD CHROMA prediction unit 31047
  • Planar prediction unit 31041 generates a prediction image q[x][y] by linearly adding multiple filtered reference images s[x][y] in accordance with the distance between the prediction pixel position and the reference pixel position, and outputs the generated image to the prediction image corrector 3105.
  • the DC prediction unit 31042 derives a DC prediction value corresponding to the average value of the filtered reference image s[x][y], and outputs a prediction image q[x][y], which takes the DC prediction value as a pixel value.
  • the Angular prediction unit 31043 generates a prediction image q[x][y] using the filtered reference image s[x][y] in a prediction direction (reference direction) indicated by the intra prediction mode, and outputs the generated image to the prediction image corrector 3105.
  • the LM prediction unit 31044 predicts the pixel value of the chroma based on the pixel value of luma. More specifically, a linear model is used to generate a prediction chroma image (Cb, Cr) based on the decoded luma image. As an example of LM prediction, there is a CCLM (cross component linear model prediction) prediction. CCLM prediction is a prediction method using a linear model to predict chroma from luma to same block.
  • the MIP prediction unit 31045 generates a prediction image q[x][y] by the product sum operation on the reference sample s[x][y] and the weight matrix derived from the neighboring region, and outputs the prediction image q[x][y] to the prediction image corrector 3105.
  • the DIMD prediction unit 31046 generates a luma prediction image using an intra prediction mode for the target block.
  • An intra prediction mode suitable for the target block is derived using the information of the adjacent regions, and the DIMD prediction unit 31046 generates a prediction luma image using the derived intra prediction mode. Details will be described later.
  • the DIMD CHROMA prediction unit 31047 generates a chroma prediction image using an intra prediction mode for the target block.
  • An intra prediction mode suitable for the target block is derived using the information of the adjacent regions, and the DIMD CHROMA prediction unit 31047 generates a chroma prediction image using the derived intra prediction mode. Details will be described later.
  • the prediction image corrector 3105 corrects the prediction image output from the intra prediction unit 3104 in accordance with the intra prediction mode. Specifically, the prediction image corrector 3105 derives, by performing weighted addition (weighted-averaging) on the unfiltered reference image and the prediction image for each pixel of the prediction image, in accordance with the distance between the reference region R and the target prediction pixel, the prediction image (corrected prediction image) Pred in which the prediction image is modified. Note that in some intra prediction modes (for example, Planar prediction, DC prediction, or the like), the prediction image corrector 3105 may not correct the prediction image, and the output of the intra prediction unit 3104 may be used as the prediction image.
  • the prediction image corrector 3105 may not correct the prediction image, and the output of the intra prediction unit 3104 may be used as the prediction image.
  • FIG.9 shows the configuration of the DIMD prediction unit 31046 in this embodiment.
  • the DIMD prediction unit 31046 comprises a reference sample derivation unit 310460, an angular mode derivation devices 310465, a prediction mode selection unit 310463 and a prediction image generation unit 310464.
  • the angular mode derivation device 310465 includes a gradient derivation unit 310461 and an angular mode derivation unit 310462.
  • the gradient derivation unit 310461 includes the filter selection unit 3104611.
  • the angular mode derivation device 310465 may include the prediction mode selection unit 310463.
  • FIG.5 shows an example of coding data about DIMD method.
  • the prediction parameter derivation unit 320 decodes a flag named dimd_flag used for indicating if this target block uses DIMD method.
  • the dimd_flag is 1, some syntax elements related to intra prediction ( intra_mip_flag, intra_luma_mpm_flag, intra_luma_mpm_idx, intra_luma_mpm_reminder ) are not decoded by the parameter decoding unit 302.
  • the intra_mip_flag indicates whether MIP prediction is used or not.
  • the intra_luma_mpm_flag is a flag for indicating if Most Probable Mode (MPM) is used.
  • MPM Most Probable Mode
  • the intra_luma_mpm_idx is an index for indicating a MPM candidate when MPM is used.
  • the intra_luma_mpm_reminder is an index for selecting a intra prediction mode from the remaining modes when MPM is not used. If dimd_flag is 0, intra_luma_mpm_flag is decoded, and if intra_luma_mpm_flag is 0 then intra_luma_mpm_reminder is decoded. When the dimd_flag of the target block is 1, then dimd_mode flag of the target block is decoded.
  • the dimd_mode flag is a flag for indicating the reference region used for deriving intra prediction mode.
  • the dimd_mode flag can be set following value.
  • dimd_flag 1
  • the DIMD prediction unit 31046 derives an angular mode indicating the texture direction in the neighboring region by pixel value. This angular mode will be used to generate an intra prediction image.
  • step1 deriving pixel gradient using the pixel values in a given position, (step 2) converting the derived pixel gradient to an angular prediction mode, (step 3) building a histogram using all the angular prediction mode obtained from step1 and step2. (step 4) One or more angular prediction modes are selected from the histogram and used to generate a prediction image.
  • FIG.9 shows the DIMD prediction unit 31046, each part of the DIMD prediction unit 31046 and the processing of each part are described in more detail in the following.
  • a process of the DIMD prediction unit 31046 is as follows: Step1: Deriving pixel gradient using the pixel values in a given position. Step2: Converting the derived pixel gradient to an angular prediction mode. Step3: Building a histogram using all the angular prediction mode obtained from step1 and step2. Step4: One or more angular prediction modes are selected from the histogram and used to generate a prediction image.
  • FIG.20 shows the configuration of the DIMD CHROMA prediction unit 31047 in this embodiment.
  • the structure of the DIMD CHROMA prediction unit 31047 is the same as the DIMD prediction unit 31046. The differences between DIMD CHROMA and DIMD methods will be described later.
  • DIMD CHROMA prediction unit 31047 applies the same process to chroma components of the target block.
  • Reference sample derivation unit 310460 derives a reference sample refUnit from the previously decoded pixel recSamples adjacent to the target block. Note that, the reference sample derivation unit 310460 may included in the reference sample filter unit 3103. FIG.10 shows an example of the reference region of the DIMD prediction unit 31046.
  • the reference sample derivation unit 310460 stores recSamples which are adjacent to target block into a reference sample refUnit and the refUnit is used by the gradient derivation unit 310461 and the prediction image generaton unit 310.
  • the reference sample derivation unit 310460 derives the reference sample refUnit from the left and top regions of the target block as follows.
  • (xC, yC) is the top-left coordinate of the target block
  • refIdxW is a constant indicating the width of the reference region on the left of target block.
  • the refIdxW may be 2, and the refH is equal to the height of target block (i.e. bH).
  • RT means the top area of target block.
  • refUnit[x][y] recSamples[xC+x][yC+y]
  • the refIdxH is a constant indicating the height of the reference region on the top of target block.
  • the refIdxH may be 2, and the refW is equal to the width of target block (i.e. bW).
  • the reference sample derivation unit 310460 derives the left and left-bottom neighboring regions of the target block.
  • refUnit[x][y] recSamples[xC+x][yC+y]
  • x -1-refIdxW...-1
  • y -1-refIdxH...refH*2-1.
  • the refIdxW and refIdxH are constants indicating the width and height of the reference region on the left of target block, respectively.
  • the refIdxW and refIdxH may be equal to 3, and the refH is equal to the height of target block (i.e. bH).
  • the reference sample derivation unit 310460 derives the top and top-right neighboring region of the target block.
  • refUnit[x][y] recSamples[xC+x][yC+y]
  • x -1-refIdxW...refW*2-1
  • y -1-refIdxH...-1.
  • the refIdxW and refIdxH are constants indicating the width and height of the reference region on the top of target block, respectively.
  • the refIdxW and refIdxH may be equal to 3, and the refW is equal to the width of target block (i.e. bW). It can also be written as follows.
  • the reference sample derivation unit 310460 derives the left and left-bottom neighboring regions of the target block.
  • the following process is performed at a position (x, y) in which located on the left area of the target block (in the following, the left area is referred to as RL (region of left), the left-bottom area is referred to as RLB (region of left-bottom)).
  • refUnit[x][y] recSamples[xC+x][yC+y]
  • x -refIdxW..-1
  • y 0..refH*2-1.
  • (xC, yC) is the top left coordinate of the target block.
  • the refIdxW and refH are constants indicating the width and height of the reference region on the left of target block, respectively.
  • the refIdxW may be equal to 3, and the refH is equal to the height of target block (i.e. bH).
  • the reference sample derivation unit 310460 derives the top and top-right neighboring regions of the target block.
  • the following process is performed in the RT and RTR.
  • RT region of top
  • RTR region of top-right
  • refUnit[x][y] recSamples[xC+x][yC+y]
  • x 0..refW*2-1
  • y -refIdxH..-1.
  • (xC, yC) is the top left coordinate of the target block.
  • the refW and refIdxH are constants indicating the width and height of the reference region on the top of target block, respectively.
  • the refIdxH may be equal to 3, and the refW is equal to the width of target block (i.e. bW).
  • RTL region of top-left is an area in which all the three areas above-mentioned are included.
  • the refIdxH and refIdxW may be equal to 3.
  • the reference region selection method may be set in following two ways. The first is to decrease the range of reference area and select only RT, RL, and RTL as the reference area (small reference area). The second is to increase the range of reference area, select RT, RL, RTL, RTR, and RLB as the reference area, and increasing the value of refIdxH and refIdxW, for example 4 (large reference area).
  • the reference sample derivation unit 310460 may use different reference regions described above , i.e. small reference region, normal reference region, and large reference region.
  • the width and height of the target block is greater than the another respective thresholds (bW>THW1
  • bH>THH1), the target block is a large block (blockType 2).
  • THW0 and THH0 may be 16 and THW1 and THH1 may be 64. It is noted that the thresholds are not only limited to the ones described above, but also may be set in other ways. THW0 and THH0 may not be the same value and THW1 and THH1 may not be the same value. For example, THW0 may be 8 and THH0 may be 16.
  • the reference sample derivation unit 310460 may derive reference region area depending on the target block’s size and/or shape.
  • the reference region area may be a small reference area, a normal referece area, or a large reference area, which may be distinguised by a region type value (regionType).
  • the reference sample derivation unit 310460 uses a small reference area for a large target block, uses a normal reference area for a normal target block, and uses a large reference area for a small target block.
  • the reference sample derivation unit 310460 uses the same reference area regardless of the size of the target area.
  • the selection of reference area is not only limited to the above examples, but also has other ways.
  • regionType is derived
  • the gradient derivation unit 310461 derives directions using the selected reference area. It is noted that without introducing intermediate values (i.e. regionType and blockType), a reference area may be directly selected depending on target block width and height.
  • the gradient derivation unit 310461 derives gradient values in two or more specific directions (for example, Dx and Dy) based on pixel values of the neighboring blocks of the target block and corresponding spatial filters (for example, a filter for Dx and another filter for Dy), and derives angle information that represents a direction of texture patterns from the gradient values (Dx and Dy).
  • the accuracy of angle information may be set in other ways , for example, it may be set to approximately 1/36 degree units.
  • the spatial filter may be a 3x3 pixel filter or a 2x2 pixel filter corresponding to the horizontal and vertical directions, as shown in FIG.11 (a, b, e, f).
  • the gradient derivation unit 310461 derives gradient values for a point P[x][y] (hereinafter simply referred to as P) in the reference sample refUnit[x][y] derived by the reference sample derivation unit 310460. It is possible to use the point recSamples[xC+x][yC+y] instead of the point refUnit[x][y] as point P.
  • FIG.12 and FIG.13 show examples of gradient target image in a target block of 8x8 pixels for 2x2 and 3x3 filters respectively.
  • the pixels in the gradient target image are used to calculate gradient.
  • the angular mode derivation unit 310462 is used for intra prediction, the meshed image in neighboring region of the target block is the gradient target image of target block (shown in FIG. 12 and FIG.13).
  • the gradient target image is the luma image of the target block.
  • the number of the pixels used for the gradient deriviation to select an angular mode (modeVal) can be changed depending on the size of the target block (bW, bH).
  • the number of the pixels used for the gradient deriviation is determined by spatial filter.
  • the number of taps of the spatial filter can be changed depending on the size of the target block.
  • the minimum number of rows of reference area required varies depending on the size of the filter. For example, a 2x2 filter requires a minimum of 2 rows, while a 3x3 filter requires a minimum of 3 rows.
  • the number of reference rows obtained from the current block's neighborhood must be greater than or equal to the minimum reference rows required by the selected filter. For rectangular filters like 3x2 and 2x3, the minimum required reference rows for horizontal and vertical directions are different.
  • the specific number of reference rows can be determined based on the filter. In this case, the reference row count is defined as the minimum reference rows required by the filter, as shown in FIG.12 (a), (b).
  • FIG.13 illustrates the region of influence for a 2x2 filter when the reference row count is set to 3.
  • the reference row count is set to "n + 1" (4).
  • FIG.14(a), (b) show the regions of influence for 2x2 and 3x3 filters when the reference row count is set to 4.
  • the value of "n” can be set in various ways (not only equal to 3), and there are multiple ways to configure the reference row count for DIMD_MODE_TOP_LEFT, DIMD_MODE_TOP, and DIMD_MODE_LEFT modes.
  • the filter selection unit 3104611 determines the size of the filter (derives a paramter filterIdx) based on the size of the target block (bW, bH).
  • a variable filterIdx is defined to indicate the currently selected filter.
  • the value of filterIdx is obtained from the following equation.
  • the filter selection unit 3104611 determines the size of the filter (e.g. whether to use a 2x2 filter or a 3x3 filter) according to the size of the target block.
  • the gradient derivation unit 310461 derive the gradient Dx and Dy in the horizontal and vertical directions respectively for each point P based on filterIdx as the following formulas.
  • the gradient derivation unit 310461 derives Dx and Dy depending on the size of the target block in which larger filter is used for larger blocks.
  • 4x4 filter may use 16 positions of (x-1, y-1), (x, y-1), (x+1, y-1) , (x+2, y-1), (x-1, y), (x, y), (x+1, y), (x+2, y), (x-1, y+1), (x, y+1), (x+1,y+1) , (x+2,y+1) , (x-1, y+2), (x, y+2), (x+1,y+2) , (x+2,y+2).
  • Similary 2x3 filter and 3x2 filter may use 6 positions (x, y-1), (x+1, y-1), (x, y), (x+1, y), (x, y+1), (x+1,y+1) and (x-1, y), (x, y), (x+1, y), (x-1, y+1), (x, y+1), (x+1,y+1) respectiely.
  • / means integer division with truncation of the result toward zero.
  • the filters of FIG.11(a,b,e,f) can be rotated by 180 degrees and become the filters of FIG.11(c,d,g,h), which is can be used for deriving gradient.
  • Dx and Dy are derived using the following equations.
  • the gradient derivation method is not only limited to the above but also can be configured in other ways.
  • the target block size determination can be conducted based on bW + bH.
  • Threshold TWH1 may be set equal to 16, 32, 64 and so on.
  • the target block size determination can be conducted based on bW * bH.
  • the target block size determination can be conducted based on log2(bW) + log2(bH).
  • the filter selection unit 3104611 may use two thresholds to select a filter from three types according to the size of target blocks: large, medium and small.
  • the filter selection unit 3104611 selects 4x4, 3x3 and 2x2 filters for large, medium and small target blocks, respectively.
  • FIG.11(i,j,m,l) shows an example of two groups of rectangular filters. Taking the filter shown in FIG.11(i,j) as an example. It is a rectangular filter (3x2 filter) with a width of 3 and a height of 2. The corresponding Dx and Dy can be calculated according to the following formula.
  • Rectangular filters are not only limited to the above two types, but also can have other kinds.
  • the filter selection unit 3104611 determines the size of the filter based on the size of the target block (bW, bH).
  • Dx P[x][y] + P[x][y+1] - P[x+1][y] - P[x+1][y+1]
  • Dx P[x-1][y+1] + 2*P[x][y+1] + P[x+1][y+1] - P[x-1][y] - 2*P[x][y] - P[x+1][y]
  • Dx 2*P[x][y-1] + 2*P[x+1][y-1] - 2*P[x][y+1] - 2*P[x+1][y+1]
  • Dx P[x-1][y+1] + 2*P[x][y+1] + P[x+1][y+1] - P[x-1][y-1] - 2*P[x][y-1] - P[x+1][y-1]
  • Dy P[x-1][y-1] + 2*P[x-1][y] + P[x-1][y+1] - P[x+1][y-1] - 2*P[x+1][y] - P[x+1][y+1]
  • the filter selection unit 3104611 may determines the size of the filter based on dimd_mode. If both of top and left neighbouring blocks are referred, larger filter (e.g. 3x3) is used otherwise smaller filter (e.g. 2x2) is used.
  • the gradient derivation unit 310461 derives Dx and Dy depending on the derived filterIdx.
  • the filter selection unit 3104611 may determine the size of the filter based on dimd_mode, in other way to use smaller blocks in case of more referenece image (e.g. DIMD_MODE_TOP_LEFT). If both of top and left neighbouring blocks is referred, larger filter (e.g. 2x2) is used otherwise smaller filter (e.g. 3x3) is used.
  • the gradient derivation unit 310461 derives Dx and Dy depending on the derived filterIdx.
  • the filter selection unit 3104611 may determines the size of the filter including rectangular kernels (e.g. 3x2, 2x3) based on dimd_mode. If both of top and left neighbouring blocks are referred, larger filter (e.g. 2x2) is used, otherwise smaller filter (e.g. 3x2) is used for DIMD_MODE_LEFT and another smaller filter (e.g. 2x3) is used for DIMD_MODE_TOP.
  • FIG.22 and FIG.23 show examples of spatial filters.
  • a variable named "filterIdx" may be used to indicate the selected filter. The range of filterIdx values is determined by the number of candidate filters.
  • filterIdx may be 0..N-1.
  • the gradient derivation unit 310461 derives gradient values for a point P[x][y] (hereinafter simply referred to as P) in the reference sample refUnit derived by the reference sample derivation unit 310460. It is possible to use the point recSamples[xC+x][yC+y] instead of the point refUnit[x][y] as point P. (xC, yC) is the top left coordinate of the target block.
  • the gradient derivation unit 310461 derive gradients of a target block using pixels of the neighboring image using different filters depending on the target block.
  • the gradient derivation unit 310461 may include the filter selection unit 3104611 and the filter selection unit 3104611 may change the weight of filters of a target block depending on the target block.
  • the filter selection unit 3104611 may derive filters and the gradient derivation unit 310461 may derive gradients using the derived filters.
  • the gradient derivation unit 310461 may directly apply the selected filter without deriving filterType value.
  • FIG.24 and FIG.25 show examples of gradient target image in a target block of 8x8 pixels for filters, respectively.
  • the pixels in the gradient target image are used to calculate gradient of each gradient derivation pixel.
  • the meshed image in neighboring region of the target block is the gradient target image of the target block.
  • the gradient target image is a luma image.
  • the number of the pixels used for the gradient deriviation to select an angular mode (modeVal) may be changed depending on the size of the target block (bW, bH).
  • the number of taps of the spatial filter spatial filter size may be changed depending on the size of the target block.
  • the filter selection unit 3104611 determines the filters (a set of filters for Dx and Dy) with different weights based on the size of the target block (bW, bH).
  • the candidate filters shown in FIG. 22 and FIG. 23 may be selected. The selection may be done according to the size of the target block, e.g. the sum of the width and height of the target block.
  • the weight values of the certain positions may be central elements or side elements in which the central elements are defined as position (x, y-1), (x-1,y), (x+1,y) and (x, y+1) in the 3x3 filter as shown FIG22. #1, #2, #3 , #4, #5 and FIG22. #1, #10, #11 and, FIG22. #1, #12, #13.
  • the side elements are defined as position (x-1, y-1), (x+1,y-1), (x-1,y+1) and (x+1, y+1) in the 3x3 filter as shown FIG22. #1, #6, #7, #8 , #9. Diagonal arrows indicates central elements wheres vertical arrows indicates side elements.
  • the filter selection unit 3104611 may select a spatial filter such that the weight of the central elements in the 3x3 filter may decrease as the block size increase to the certatin size and increase as the size of block size.
  • the filter selection unit 3104611 may select a spatial filter such that the weight of the side elements in the 3x3 filter may decrease as the block size increase to the certatin size and increase as the size of block size.
  • the filter selection unit 3104611 may directly use corresponding spatial filters and conditions without deriving intermediate values, i.e. THArray and filterCandList.
  • filterCandList may be [#1,#2,#3,#2,#1] or [#1,#3,#5,#3,#1].
  • filterCandList may be [#1,#2,#3,#4,#5].
  • filterCandList may be [#5,#4,#3,#2,#1].
  • filterCandList may be [#7,#6,#1,#6,#7].
  • filterCandList may be [#1,#6,#7,#8,#9].
  • the threshold value in the above examples may be changed from [40,64,128,256] to [32,64,128,256] or others.
  • the number and value of thresholds may be used.
  • the filter selection unit 3104611 selects filters (a set of filter for Dx and Dy) with different size (the size of the filter) depending on the size of the target block. For example, for small target blocks, a 2x2 filter is selected, for medium target blocks, a 3x3 filter is selected, and for large target blocks, a 4x4 filter is selected.
  • THArray may be [64, 128] and filterCandList may be [#15, #1, #22].
  • the filter selection unit 3104611 selects small filters for large blocks and large filters for small blocks
  • THArray may be set to [#64, #128] and filterCandList may be [#22, #1, #15].
  • the filter selection unit 3104611 may select filter depending on the the product of the block width and block height. e.g. bW x bH, where THArray may be [1024, 4096].
  • the filter selection unit 3104611 may select filter depending on the sum of logarithmic block width and block height, e.g. log(bW) + log(bH) where THArray may be [#10, #12].
  • the filter selection unit 3104611 may selects filter depending on the product of logarithmic block width and block height. e.g. log(bW) x log(bH) where THArray may be [25, 36].
  • the filter selection unit 3104611 may select filter depending on block width and block height. e.g.
  • MxM and NxN filters may be represented with MxM filter with zero value in specific positions (e.g. 2x2 filter may be 3x3 with kind of L shape five zeros in it).
  • the filter selection unit 3104611 may select filters such that the weight of the center elements may be different depending on the block shape.
  • the 3x2 filter is used for the target block whose width is greater than the height
  • the 2x3 filter is used for the target block whose height is greater than the width
  • the filter selection unit 3104611 may select filters as follows.
  • MxN and NxN filters may be represented with LxL filter with zero value in specific positions (e.g. 3x2 filter may be 3x3 with 3x1 zero in it and 2x3 filter may be 3x3 with 1x3 zero in it).
  • the gradient derivation unit 310461 derives the gradient Dx and Dy in the horizontal and vertical directions respectively for each point P based on filter as the following formulas.
  • the gradient derivation unit 310461 derives Dx and Dy, depending on the size or the shape of the target block.
  • the size or the shape of the target block may be used to derive the weight of the filters.
  • a variable named "filterIdx" may be used to indicate the selected filter being used.
  • a 2x2 filter may use four positions of (x, y), (x+1, y), (x, y+1), (x+1,y+1) whereas a 3x3 filter may use nine positions of (x-1, y-1), (x, y-1), (x+1, y-1), (x-1, y), (x, y), (x+1, y), (x-1, y+1), (x, y+1), (x+1,y+1).
  • 4x4 filter may use 16 positions of (x-2, y-2), (x-1, y-2), (x, y-2) , (x+1, y-2), (x-2, y-1), (x-1, y-1), (x, y-1), (x+1, y-1), (x-2, y), (x-1, y), (x+1,y) , (x-2, y+1), (x-1, y+1), (x,y+1) , (x+1,y+1).
  • Similary 2x3 filter and 3x2 filter may use 6 positions (x, y-1), (x+1, y-1), (x, y), (x+1, y), (x, y+1), (x+1,y+1) and (x-1, y), (x, y), (x+1, y), (x-1, y+1), (x, y+1), (x+1,y+1) respectiely.
  • the signs of each component of the above equations may be reversed, i.e.
  • the filters may be rotated by 180 degrees, which is also may be used for deriving gradient.
  • Dx and Dy are derived using the following equations.
  • Dy -P[x][y+1] - P[x+1][y+1] + P[x][y] + P[x+1][y]
  • Rotating filterType #2 rotated filter is applied as follows
  • Dy P[x-1][y-1] + 2*P[x][y-1] + P[x+1][y-1] - P[x-1][y+1] - 2*P[x][y+1][y+1]
  • Dx P[x+1][y-1] + 2*P[x+1][y] + P[x+1][y+1] - P[x+1][y+1] D
  • Range for gradient derivation The position ranges (x, y) used for histogram counting which is used for deriving gradient are located in the reference regions RL, RT, RTL, RTR and RLB.
  • the range (x, y) of the gradient derivation corresponding to RL, RT, RTL, RTR and RLB is referred to as RDL, RDT, RDTL, RDTR and RDLB which is showed in FIG.26, FIG.26 shows an example of 3x3 filter.
  • the range of reference region should be larger than the range of gradient derivation if the applied filter size is taken account. e.g. 3 tap filter access, x-1, x, x+1 for position x.
  • the gradient derivation unit 310461 may change/extend the reference region depending on the derived filter size.
  • the gradient derivation unit 310461 may change/reduce the gradient derivation region depending on the derived filter size.
  • the gradient derivation unit 310461 derives the angular information composed of a angle quadrant of the texture of the target block and a angle within this quadrant according to the relationship of Dx and Dy. By using quadrant, the processing in some directions with rotational symmetry or line symmetry relationship may be unifized. However, angular information is not limited to quadrants and angles within quadrants. For example, angle information may be set as angle only, and the quadrants are derived as needed from this angle. In addition, in this embodiment, the derived intra direction prediction modes are limited to the direction from bottom-left to top-right (2 to 66 in FIG.3), and the intra direction prediction modes in the 180 degree rotation symmetric direction are the same as this.
  • FIG.15 (a) is a table shows the relationship of the sign (signx, signy), the size relationship xgty and the quadrant (Ra to Rd) of the Dx and Dy.
  • FIG.15 (b) shows the quadrants of Ra to Rd.
  • the angular information may be derived from the signx, signy, and xgty.
  • the gradient derivation unit 310461 derives the quadrant from the signx, signy, and xgty, using the following operation or table reference.
  • the gradient derivation unit 310461 may refer to the table of FIG.15(a) to derive the quadrant.
  • the value of the quadrant is not limited to the above.
  • the angular mode derivation device 310465 is used to derive the angular mode. It includes two parts: the gradient derivation unit 310461 and the angular mode derivation unit 310462.
  • the gradient derivation unit 310461 is used to derive the gradient according to the pixel
  • the angular mode derivation unit 310462 is used to derive the angle according to the gradient.
  • the filters and reference areas used in the gradient derivation unit 310461 may be changed based on the size and shape of the target block.
  • the angular mode derivation unit 310462 derives an angular mode (a prediction mode corresponding to the target block, for example, an intra prediction mode) based on the gradient information of the points P[x][y].
  • FIG.16 is a block diagram showing one configuration of the angular mode derivation unit 310462. As shown in FIG.16, the first gradient, the second gradient, and two tables are used to derive an angular mode(mode_delta or modeVal).
  • the angular mode derivation unit 310462 comprises an angular coefficient derivation unit 310466 and a mode transformation unit 310467.
  • Angular coefficient derivation unit 310466 derives an angular coefficient iRatio (or v) based on two gradients.
  • 8" (OR calculation with 8) may be calculated by "+ 8".
  • 64” in the following description may be calculated with “+ 16", “+ 32", and “+ 64", respectively.
  • x is a integer part of a logarithm value of third gradient value s1 (absx or absy) of a pixel.
  • norm_s1 is derived by using the third gradient s1 to perform a shift operation ofx.
  • the angle coefficient v is determined by using norm_s1 and the reference table gradDivTable.
  • iRatio is derived by the product of v and the fourth gradient s0 with shift operation based on x.
  • iRatio and angTable to export angle mode mode_delta. A clipping operation is performed in the following manner for making sure that the iRatio does not exceed the range of the numbers of angTable.
  • iRatio min((s0 * v) ⁇ 3 >> x, N_LUT-1)
  • s0*v (min(s0*v, KK) ⁇ 3) >> x
  • iRatio may be derived by reversing the definition of s0 and s1.
  • the number of occurrences of modeVal is recorded in a histogram (HistMode[]).
  • the prediction mode selection unit 310463 derives one or more intra prediction modes dimdModeVal (dimdModeVal0, dimdModeVa1, dimdModeVal2, dimdModeVal3, dimdModeVal4) using the histogram HistMode[].
  • the histogram is derived by modeVal (modeVal) calculated by a plurality of points P which is belong to the gradient derivation target image.
  • the dimdModeVal in this embodiment, is the estimated value of the dominant texture direction of the target block.
  • the dimdModeVal is derived by finding the most frequent value (mode value) in the histogram.
  • the first mode dimdModeVal0 is derived by selecting a mode having the highest frequency (largetst occurrence)
  • the second mode dimdModeVal1 is derived by selecting a mode having the second highest frequency (the second largest occurrence).
  • scan the HistMode[x] to give the x having maximum value in the HistMode to determine dimdModeVal0 ( argmax(HistMode))
  • cntMode may be 67.
  • the method of deriving dimdModeVal0, dimdModeVal1, ... is not limited to the histogram.
  • the prediction mode selection unit 310463 may set the mean value of modeVal to dimdModeVar0 or dimdModeVal1.
  • the prediction mode selection unit 310463 sets dimdModeVal2 a predetermined mode as the third mode.
  • the third mode is set equal to planar mode (0), but not limited to planar mode.
  • Other modes may be adaptively set as third mode or the thirdthird mode may not be used.
  • the angular mode selection unit 310463 may derive weights of these three modes above-mentioned which are used in the prediction image generation unit 310464.
  • the weighting of the first, second, and third modes is not limited to this, and the weights W0, W1, W2 of the first, second, and third modes may be changed. For example, W1 may be increased or decreased.
  • the angle mode selection section sets a weight to 0 means the mode corresponding to this weight is not used.
  • the reference region of the reference image used for deriving the intra prediction mode is changed in accordance with the dimd_mode. Specifically, the position of points P used in the gradient derivation unit 310461, the angle mode derivation unit 310462, and the angular mode selection unit 310463 are changed in accordance with the dimd_mode.
  • the position ranges (x, y) used for histogram counting for deriving gradient and angular mode are located in the reference regions RL, RT and RTL.
  • 3x3 filter in the range for gradient deriving, the start point is made by increasing 1 and the end point is made by reducing 1.
  • FIG.17(b) shows an example of the reference range used in the processing of gradient derivation of the dimd prediction.
  • the angular mode derivation unit 310462 derives Dx and Dy from the each point P of the left region RDL of the target block, derives modeVal and conducts histogram counting operation. Subsequently, Dx and Dy are derived from each point P of the above region RDT of the target block, and modeVal is derived and histogram counting is conducted.
  • the angular mode derivation unit 310462 use the extension left region RDL_EXT of the target block, for example, Dx and Dy from the RDL_EXT, for deriving and counting modeVal.
  • the angular mode derivation unit 310462 derives modeVal from the extension above region RDT_EXT of the target block, and conducts histogram counting.
  • the reference region for gradient deriving is shown in FIG.16(a).
  • RDTL is an area in which RDL and RDT are combined.
  • the prediction mode selection unit 310463 selects an intra prediction mode from a plurality of angular modes derived by pixels in the gradient derivation target image, thus, can obtain an angular mode with higher accuracy. As described above, the prediction mode selection unit 310463 selects the angular mode estimated from the gradient and outputs with the weight corresponding to each angular mode.
  • Prediction image generation unit 310464 The prediction image generating unit 310464 generates a prediction image using two or three intra prediction mode, one of them is set as planar mode, other one or two intra prediction mode is angular mode input from the angular mode selection unit 310463. First, prediction images (pred0, pred1, pred2) according to each intra prediction mode are generated. Second, these prediction images are synthesized using corresponding weights (w0, w1, w2), and outputed as a prediction image q[x][y]. The prediction image q[x][y] is derived as follows.
  • q[x][y] (w0 * pred0[x][y] + w1 * pred1[x][y] + w2 * pred2[x][y]) >> 6
  • the prediction image q[x][y] is generated by the first and second mode as follows.
  • q[x][y] (w0 * pred0[x][y] + w1 * pred1[x][y]) >> 6
  • the first and second mode is angular mode
  • the third mode is plannar mode.
  • the prediction image generating unit 310464 generates a prediction image using the intra prediction mode derived in Angular mode derivation device 310465.
  • the prediction image generating unit 310464 may generates a prediction image q[x][y] using derived intra prediction in the angular mode derivation device 310465.
  • q[x][y] w0 * pred0[x][y]
  • the prediction image generating unit 310464 may generates a prediction image q[x][y] using two intra prediction mode derived in the angular mode derivation device 310465.
  • the prediction image generating unit 310464 may generates a prediction image q[x][y] using one or more more intra prediction mode derived in the angular mode derivation device 310465.
  • q[x][y] (w0 * pred0[x][y] + w1 * pred1[x][y] + wP * predP[x][y] + 32 ) >> 6 where pred0, pred1 and predP is the prediction image with IntraPredModeY being dimdModeVal0, prediction image with IntraPredModeY being dimdModeVal1, and prediction image with IntraPredModeY being planar mode.
  • the prediction image generating unit 31046 may derive weights of dimdModeVal0, dimdModeVal1 and planar mode as w0, w1 wP.
  • the weight w0 and w1 is derived using the ratio of the occurence of the first and second modes in the histogram, HistMode[dimdModeVal0] and HistMode[dimdModeVal1].
  • wP may be set equal to 21.
  • the weighting of the first, second, and third modes is not limited to this. For example, w1 may be increased or decreased.
  • the prediction image generating unit 310464 may generate a prediction image using one or more more intra prediction mode.
  • the numebr of intra prediction mode N may be 2 to 6. one of them may be set as planar mode, other intra prediction modes are angular mode derived in the angular mode derivation device 310465.
  • prediction images pred0, pred1, pred2, pred3, pred4, predP
  • these prediction images are synthesized using corresponding weights (w0, w1, w2, w3, w4, wP), and output as a prediction image q[x][y].
  • the prediction image q[x][y] is derived as follows.
  • DIMD CHROMA prediction unit 31047 The followings are detailed explanation for DIMD CHROMA prediction unit 31047.
  • DIMD CHROMA prediction unit 31047 generate a chroma prediction image.
  • the ChromaFusionFlag is used to indicate whether the current target block uses the DIMD CHROMA method for chroma intra prediction. If ChromaFusionFlag is 1, the DIMD CHROMA prediction unit 31047 derives an angular mode indicating the texture direction in the neighboring region by pixel value. This angular mode will be used to generate the chroma prediction image.
  • Reference sample derivation unit 310470 derives a reference sample refUnit from the previously decoded pixel recSamples adjacent to the target block.
  • the reference sample of DIMD CHROMA may includes luma components in addition to chroma ponponent, Cb or Cr.
  • the reference sample derivation unit 310470 may refer one or more reference areas in chroma : e.g. left, top, top-left, top-right, and left-bottom areas of the target block in chroma (Cb or Cr) components.
  • the regions are refred as RTL_cr, RT_cr, RL_cr, RTR_cr, and RLB_cr for Cr region and RTL_cb, RT_cb, RL_cb, RTR_cb, and RLB_cb for Cb region.
  • the reference sample derivation unit 310470 may refer one or more luma reference areas in luma : e.g.
  • left, top, top-left, top-right, and left-bottom areas adjacent of the target block RTL, RT, RL, RTR, and RLB
  • the derivation method of the left, top, top-left, top-right, and bottom-left samples of the target block is the same for the DIMD CHROMA and DIMD methods. The specific methods are described in DIMD prediction and will not be repeated here.
  • the reference sample derivation unit 310470 may refer a prediction image of the luma target block denoted as RLTAR (region of luma target block). It is noted that when generating the chroma prediction image, the prediction image of the luma target block has already been generated, so the pixels in the luma target block may also be used to generate the chroma prediction image.
  • x 0..bW-1
  • y 0..bH-1
  • bW and bH are the width and height of the target luma block.
  • (xC, yC) is the top left coordinate of the luma target block.
  • the reference regions used in the DIMD CHROMA method may vary.
  • the reference sample derivation unit 310470 in embodiment A, B, and C may refer chroma regions only, chroma regions plus luma regions, and chroma and luma and luma prediction regions, respectively.
  • the embodiment is utilized depending on peformance-complexity balance. Low complexity case may use A, medium complexity case may use B and high complexity but high peformance case may uses C.
  • the specific selection of which reference regions to be used may be determined based on the target block. For example, the reference area may be selected according to the size of the target block as described in 310460.
  • the angular mode derivation device 310475 is used to derive the angular mode. It includes two parts: the gradient derivation unit 310471 and the angular mode derivation unit 310472.
  • the gradient derivation unit 310471 is used to derive the gradient according to the pixel
  • the angular mode derivation unit 310472 is used to derive the angle according to the gradient.
  • the filters and reference areas used in the gradient derivation unit 310471 may be changed based on the size and shape of the target block.
  • the gradient derivation unit 310471 is the same as the gradient derivation unit 310461 but is applied for the chroma reference regions, the luma reference regions and the luma prediction image (luma target region). It derives gradient values in two or more specific directions (for example, Dx and Dy) for each regions based on pixel values of the regions of the target block, and derives angular information that represents a direction of texture patterns from the gradient values for each regions.
  • FIG.27 is a block diagram showing one configuration of the angular mode derivation unit 310472. Because the angular mode derivation unit 310472 is the same as the angular mode derivation unit 310462, details is ommited.
  • Angular mode selection unit 310473 derives one or more angular modes dimdChromaModeVal (dimdchromamodeVal0, dimdchromamodeVal1,...) using the histogram derived by modeVal calculated by a plurality of points P which is belong to the gradient derivation target image. Because the prediction mode derivation unit 310473 is the same as the prediction mode selection unit 310463, details is ommited.
  • the position ranges (x, y) used for histogram counting to derive the gradient are located in the reference regions RL, RT, RTL, RTR, RLB, and RLTAR.
  • the range of the gradient derivation corresponding to RL, RT, RTL, RTR, RLB, and RLTAR are referred to as RDL, RDT, RDTL, RDTR, RDLB, and RDLTAR as shown in FIG.28.
  • the position ranges (x, y) used for histogram counting to derive the gradient and the angular mode are located in the reference regions RL_cb, RT_cb, RTL_cb, RTR_cb, and RLB_cb.
  • the range of the gradient derivation corresponding to RL_cb, RT_cb, RTL_cb, RTR_cb, and RLB_cb are referred to as RDL_cb, RDT_cb, RDTL_cb, RDTR_cb, and RDLB_cb as shown in FIG.28.
  • the chroma (Cr) component is the same as chroma (Cb) component, and the range (x, y) of the gradient derivation corresponding to RL_cr, RT_cr, RTL_cr, RTR_cr, and RLB_cr are referred to as RDL_cr, RDT_cr, RDTL_cr, RDTR_cr, and RDLB_cr as shown in FIG.28.
  • the prediction mode selection unit 310473 has the function that is selecting an angular mode from a plurality of angular modes derived by pixels in the gradient derivation target image, thus, may obtain an angular mode with higher accuracy. As described above, the prediction mode selection unit 310473 selects the angular mode estimated from the gradient and outputs with the weight corresponding to each angular mode.
  • the prediction image generating unit 310474 generates a chroma prediction image using the chroma intra prediction mode derived in angular mode derivation device 310475.
  • the prediction image generating unit 310474 may generates a chroma prediction image q[x][y] using derived chroma intra prediction in the angular mode derivation device 310475.
  • q[x][y] w0 * pred0[x][y]
  • the prediction image generating unit 310474 may generates a chroma prediction image q[x][y] using two chroma intra prediction mode derived in the angular mode derivation device 310475.
  • the prediction image generating unit 310474 may generates a chroma prediction image q[x][y] using one or more more chroma intra prediction mode derived in the angular mode derivation device 310475.
  • q[x][y] (w0 * pred0[x][y] + w1 * pred1[x][y] + wP * predP[x][y] + 32 ) >> 6 where pred0, pred1 and predP is the chroma prediction image with IntraPredModeC being dimdModeVal0, and chroma prediction image with IntraPredModeC being dimdModeVal1, and chroma prediction image with IntraPredModeC being planar mode.
  • the prediction image generating unit 310474 may generates a chroma prediction image q[x][y] using one or more more chroma intra prediction mode derived in the angular mode derivation device 310475.
  • predLM is the prediction image with IntraPredModeC being CCLM (cross component linear model), MMLM (multi mode linear model).
  • predC is a prediction image value of the target block and a, b, shift is integer variables.
  • linear model parameter (a, b, and shift) is derived from neibouring chroma pixel value and luma pixel value of the target block.
  • the inverse quantization and inverse transform processing unit 311 performs inverse quantization on a quantization transform coefficient input from the prediction parameter derivation unit 320 to calculate a transform coefficient.
  • This quantization transform coefficient is a coefficient obtained by performing a frequency transform such as a Discrete Cosine Transform (DCT), a Discrete Sine Transform (DST), or the like on prediction errors to quantize in coding processing.
  • the inverse quantization and inverse transform processing unit 311 performs an inverse frequency transform such as an inverse DCT, an inverse DST, or the like on the calculated transform coefficient to calculate a prediction error.
  • the inverse quantization and inverse transform processing unit 311 outputs the prediction error to the addition unit 312.
  • FIG.18 is a block diagram showing the configuration of the inverse quantization and inverse transform processing unit 311 of this embodiment.
  • the inverse quantization and inverse transform processing unit 311 comprises a scaling unit 31111, an inverse non separation transformer 31121 and a inverse separation transformer 31123.
  • the inverse quantization and inverse transform processing unit 311 transforms transformation coefficients which are decoded from the coded data by using the angular mode derived by the angular mode derivation device 310465.
  • the inverse quantization and inverse transform processing unit 311 obtains transformation coefficient d[][] by using in sacling unit 31111 to scale the the quantization conversion coefficient qd[][] inputed from the prediction parameter derivation unit 320.
  • the quantization transformation coefficient qd[][] is the coefficients obtained from the quantizing processing. Quantizing operation is performed by doing the DCT (Discrete Cosine Transform) or DST (Discrete Sine Transform) or the like transformation operation to the prediction error in the coding process. In some cases, non separation transform may be performed for obtaining the quantization transformation coefficient qd[][].
  • the addition unit 312 adds the prediction image of the block input from the intra prediction image generation unit 310 and the prediction error input from the inverse quantization and inverse transform processing unit 311 for each pixel and generates a decoded image of the block.
  • the addition unit 312 stores the decoded image of the block in the reference picture memory 306 and outputs the image to the loop filter 305.
  • FIG. 19 is a block diagram illustrating a conuration of the video coding apparatus 11 according to the present embodiment.
  • the video coding apparatus 11 is configured to include a prediction image generation unit 101, a subtraction unit 102, a transform and quantization processing unit 103, an inverse quantization and inverse transform processing unit 105, an addition unit 106, a loop filter 107, a prediction parameter memory (a prediction parameter storage unit, a frame memory) 108, a reference picture memory (a reference image storage unit, a frame memory) 109, a coding parameter determination unit 110, a parameter coding unit 111, prediction parameter derivation unit 120, and an entropy coding unit 104.
  • a prediction image generation unit 101 a subtraction unit 102, a transform and quantization processing unit 103, an inverse quantization and inverse transform processing unit 105, an addition unit 106, a loop filter 107, a prediction parameter memory (a prediction parameter storage unit, a frame memory) 108, a reference picture memory (a
  • the prediction image generation unit 101 generates a prediction image for each CU that is a region obtained by splitting each picture of the image T.
  • the operation of the prediction image generation unit 101 is the same as that of the intra prediction image generation unit 310 already described, and thus descriptions thereof will be omitted.
  • the subtraction unit 102 subtracts a pixel value of the prediction image of the block input from the prediction image generation unit 101 from a pixel value of the image T to generate a prediction error.
  • the subtraction unit 102 outputs the prediction error to the transform and quantization processing unit 103.
  • the transform and quantization processing unit 103 calculates a transform coefficient by performing a frequency transform on the prediction error input from the subtraction unit 102, and derives a quantization transform coefficient by quantization.
  • the transform and quantization processing unit 103 outputs the quantization transform coefficient to the entropy coding unit 104 and the inverse quantization and inverse transform processing unit 105.
  • the inverse quantization and inverse transform processing unit 105 is the same as the inverse quantization and inverse transform processing unit 311 (FIG. 4) in the video decoding apparatus 31, and descriptions thereof are omitted.
  • the calculated prediction error is output to the addition unit 106.
  • the quantization transform coefficient is input from the transform and quantization processing unit 103, and coding parameters are input from the parameter coding unit 111.
  • the entropy coding unit 104 performs entropy coding on split information, the prediction parameters, the quantization transform coefficient, and the like to generate and output the coding stream Te.
  • the parameter coding unit 111 instructs the entropy coding unit 104 to encode the prediction parameters and quantization coefficients, derived from the prediction parameter derivation unit 120.
  • the prediction parameter derivation unit 120 derives the syntax element from the parameters inputted from the coding parameter determination unit 110. Some parts of the prediction parameter derivation unit 120 have the same structure as the prediction parameter derivation unit 320.
  • the addition unit 106 adds a pixel value of the prediction image of the block input from the prediction image generation unit 101 and the prediction error input from the inverse quantization and inverse transform processing unit 105 to each other for each pixel, and generates a decoded image.
  • the addition unit 106 stores the generated decoded image in the reference picture memory 109.
  • the loop filter 107 applies a deblocking filter, an SAO, and an ALF to the decoded image generated by the addition unit 106.
  • the loop filter 107 need not necessarily include the above-described three types of filters, and may have a configuration of only the deblocking filter, for example.
  • the prediction parameter memory 108 stores the prediction parameters generated by the prediction parameter derivation unit 120 for each target picture and CU at a predetermined position. It may stores the transform coefficients created by the transform and quantization processing unit 103.
  • the reference picture memory 109 stores the decoded image generated by the loop filter 107 for each target picture and CU at a predetermined position.
  • the coding parameter determination unit 110 selects one set among multiple sets of coding parameters.
  • a coding parameter refers to the above-mentioned QT, BT, or TT split information, the prediction parameter, or a parameter to be coded, the parameter being generated in association therewith.
  • the prediction image generation unit 101 generates the prediction image by using these coding parameters.
  • the coding parameter determination unit 110 calculates, for each of the multiple sets, an RD cost value indicating the magnitude of an amount of information and a coding error.
  • the RD cost value is, for example, the sum of a code amount and the value obtained by multiplying a coefficient ⁇ by a square error.
  • the coding parameter determination unit 110 selects a set of coding parameters of which cost value calculated is a minimum value. With this configuration, the entropy coding unit 104 outputs the selected set of coding parameters as the coding stream Te.
  • the coding parameter determination unit 110 outputs the determined coding parameters in the parameter coding unit 111, the prediction parameter derivation unit 120, the prediction image generation unit 101.
  • some of the video coding apparatus 11 and the video decoding apparatus 31 in the above-described embodiment for example, the entropy decoding unit 301, the parameter decoding unit 302, the loop filter 305, the intra prediction image generation unit 310, the inverse quantization and inverse transform processing unit 311, the addition unit 312, the prediction parameter derivation unit 320, the prediction image generation unit 101, the subtraction unit 102, the transform and quantization processing unit 103, the entropy coding unit 104, the inverse quantization and inverse transform processing unit 105, the loop filter 107, the coding parameter determination unit 110, and the parameter coding unit 111, the prediction parameter derivation unit 120, may be realized by a computer.
  • this configuration may be realized by recording a program for realizing such control functions on a computer-readable recording medium and causing a computer system to read the program recorded on the recording medium for execution.
  • the “computer system” mentioned here refers to a computer system built into either the video coding apparatus 11 or the video decoding apparatus 31 and is assumed to include an OS and hardware components such as a peripheral apparatus.
  • a “computer-readable recording medium” refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, and the like, and a storage device such as a hard disk built into the computer system.
  • the “computer-readable recording medium” may include a medium that dynamically stores a program for a short period of time, such as a communication line in a case that the program is transmitted over a network such as the Internet or over a communication line such as a telephone line, and may also include a medium that stores the program for a fixed period of time, such as a volatile memory included in the computer system functioning as a server or a client in such a case.
  • the above-described program may be one for realizing some of the above-described functions, and also may be one capable of realizing the above-described functions in combination with a program already recorded in a computer system.
  • a part or all of the video coding apparatus 11 and the video decoding apparatus 31 in the embodiment described above may be realized as an integrated circuit such as a Large Scale Integration (LSI).
  • LSI Large Scale Integration
  • Each function block of the video coding apparatus 11 and the video decoding apparatus 31 may be individually realized as processors, or part or all may be integrated into processors.
  • the circuit integration technique is not limited to LSI, and the integrated circuits for the functional blocks may be realized as dedicated circuits or a multi-purpose processor. In a case that with advances in semiconductor technology, a circuit integration technology with which an LSI is replaced appears, an integrated circuit based on the technology may be used.
  • the embodiment of the present invention may be applied to a video decoding device that decodes encoded data of image data, and a video encoding device that generates encoded data from image data.
  • the data structure of the encoded data is generated by the video encoding device and referenced by the video decoding device.

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Abstract

L'invention améliore la précision du procédé DIMD et DIMD CHROMA pour une prédiction intra sans coûts supplémentaires. Le poids, la taille et la forme du filtre utilisé pour dériver le gradient peuvent être modifiés en fonction de la taille et de la forme du bloc cible.
EP23903207.1A 2022-12-16 2023-11-17 Appareil de génération d'image de prédiction, appareil de décodage vidéo, appareil de codage vidéo et procédé de génération d'image de prédiction Pending EP4635172A1 (fr)

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JP2023033764 2023-03-06
PCT/JP2023/041397 WO2024127909A1 (fr) 2022-12-16 2023-11-17 Appareil de génération d'image de prédiction, appareil de décodage vidéo, appareil de codage vidéo et procédé de génération d'image de prédiction

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