Video decoding device and image encoding device

Abstract

To provide a video image decoding device and image encoding device which execute prediction refinement with optical flow (PROF) prediction.SOLUTION: A video image decoding device includes an affine prediction unit which derives an affine prediction parameter from motion vectors of multiple control points; and a prediction refinement with optical flow (PROF) unit which receives, as input, a motion vector difference array derived from the affine prediction parameter and a predicted image array derived from the affine prediction parameter to derive a prediction sample value from the motion vector difference array and the prediction image array. The motion vector difference array is clipped in a range using a fixed value independent of a pixel bit length.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a predicted image generating device, a video decoding device, and a video encoding device. [Background technology]

[0002] In order to efficiently transmit or record moving images, a moving image encoding device is used that encodes moving images to generate coded data, and a moving image decoding device is used that decodes the coded data to generate decoded images.

[0003] Specific video encoding methods include, for example, H.264 / AVC and HEVC (High-Efficiency Video Coding) methods.

[0004] In such a video coding method, images (pictures) constituting a video are divided into slices obtained by dividing the image, coding tree units (CTUs) obtained by dividing the slices, and coding tree units (CTUs) obtained by dividing the coding tree units. The coding unit (sometimes called a coding unit (CU)) that is used for encoding, and The coding unit is divided into transform units (TUs) and managed in a hierarchical structure, and is coded / decoded for each CU.

[0005] In such video coding methods, a predicted image is usually generated based on a locally decoded image obtained by encoding / decoding an input image, and the predicted image is subtracted from the input image (original image) to obtain a prediction error (sometimes called a "difference image" or "residual image"), which is then coded. Methods for generating predicted images include inter-frame prediction (inter-prediction) and intra-frame prediction (intra-prediction).

[0006] Non-Patent Document 1 is another recent example of a video encoding and decoding technique. Non-Patent Document 1 describes a number of merge predictions, one of which is triangle prediction, in which a current block is divided into triangular regions and a different inter prediction is performed for each region. Dividing the current block into shapes other than rectangular enables more accurate prediction even for complex textures, improving encoding efficiency. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] "Versatile Video Coding (Draft 6)", JVET-O2001-vE, Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11 Summary of the Invention [Problem to be solved by the invention]

[0008] Non-Patent Document 1 discloses the techniques of PROF (Prediction Refinement with Optical Flow), Triangle prediction, and Weighted prediction. However, the relationship between the two prediction methods, PROF and Weighted prediction, and Triangle prediction and Weighted prediction, is not clear, and there is a problem in that it is not clearly defined whether they can be executed simultaneously, or if not, how they should be distinguished when executed.

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a video decoding device, an image coding device, and a predicted image generating method that realize a method of exclusively executing one of two prediction methods or a method of simultaneously executing two prediction methods. be. [Means for solving the problem]

[0010] A video decoding device according to one aspect of the present invention includes an affine prediction unit that derives affine prediction parameters from motion vectors of a plurality of control points, and further includes a prediction refinement with optical flow (PROF) unit that receives a motion vector difference array derived from the affine prediction parameters and a predicted image array derived from the affine prediction parameters and derives predicted sample values ​​from the motion vector difference array and the predicted image array, and the motion vector difference array is It is characterized by being clipped within a range using a fixed value that is independent of the pixel bit length.

[0011] A video encoding device according to one aspect of the present invention includes an affine prediction unit that derives affine prediction parameters from motion vectors of a plurality of control points, and further includes a prediction refinement with optical flow (PROF) unit that receives a motion vector difference array derived from the affine prediction parameters and a predicted image array derived from the affine prediction parameters and derives predicted sample values ​​from the motion vector difference array and the predicted image array, and the motion vector difference array is , characterized in that the image is clipped within a range using a fixed value that is independent of the pixel bit length. [Effects of the Invention]

[0012] According to one aspect of the present invention, it is possible to provide a video decoding device, or an image coding device and a predicted image generation method that realizes a method of exclusively executing one of two prediction methods, or a method of simultaneously executing two prediction methods, without reducing coding efficiency. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing the configuration of an image transmission system according to an embodiment of the present invention. [Figure 2]1 is a diagram showing the configuration of a transmitting device equipped with a video encoding device according to this embodiment, and a receiving device equipped with a video decoding device, where (a) shows the transmitting device equipped with the video encoding device, and (b) shows the receiving device equipped with the video decoding device. [Figure 3] 1A and 1B are diagrams showing the configurations of a recording device equipped with a video encoding device according to an embodiment of the present invention, and a playback device equipped with a video decoding device, where (a) shows the configuration of a recording device equipped with a video encoding device, and (b) shows the configuration of a playback device equipped with a video decoding device. [Figure 4] FIG. 2 is a diagram showing a hierarchical structure of data in an encoded stream. [Figure 5] FIG. 10 is a diagram illustrating an example of division of a CTU. [Figure 6] FIG. 1 is a conceptual diagram illustrating an example of a reference picture and a reference picture list. [Figure 7] FIG. 1 is a schematic diagram illustrating a configuration of a video decoding device. [Figure 8] 10 is a flowchart illustrating a schematic operation of the video decoding device. [Figure 9] FIG. 10 is a schematic diagram showing the configuration of an inter-prediction parameter derivation unit. [Figure 10] 1 is a schematic diagram showing the configuration of a merge prediction parameter derivation unit and an AMVP prediction parameter derivation unit. [Figure 11] FIG. 10 is a diagram showing affine prediction motion vectors spMvLX[xi][yi]. [Figure 12] FIG. 2 is a schematic diagram showing the configuration of a PROF unit. [Figure 13] FIG. 10 is a diagram illustrating application conditions for PROF processing. [Figure 14] FIG. 10 is a schematic diagram showing the configuration of an inter-prediction image generation unit. [Figure 15] FIG. 1 is a block diagram showing a configuration of a video encoding device. [Figure 16] FIG. 10 is a schematic diagram showing the configuration of an inter-prediction parameter encoding unit. [Figure 17] FIG. 10 is a diagram illustrating a triangle prediction. [Figure 18] FIG. 2 is a diagram illustrating a configuration of a triangle synthesis unit according to the present embodiment. [Figure 19] FIG. 10 is a diagram illustrating the syntax of coding parameters for weighted prediction. [Figure 20] FIG. 10 is a diagram illustrating the syntax of coding parameters for weighted prediction. DETAILED DESCRIPTION OF THE INVENTION

[0014] (First embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] FIG. 1 is a schematic diagram showing the configuration of an image transmission system 1 according to this embodiment.

[0016] The image transmission system 1 is a system that transmits an encoded stream obtained by encoding a target image, decodes the transmitted encoded stream, and displays the image. The image transmission system 1 includes a video encoding device (image encoding device) 11, a network 21, a video decoding device (image decoding device) 31, and a video display device (image display device) 41.

[0017] An image T is input to the video encoding device 11 .

[0018] The network 21 transmits the coded stream Te generated by the video coding device 11 to the video decoding device 31. The network 21 may be the Internet, a wide area network (WAN), a local area network (LAN), or any of these. The network 21 is a combination of the above. The network 21 is not necessarily limited to a two-way communication network, but may be a one-way communication network that transmits broadcast waves such as terrestrial digital broadcasting, satellite broadcasting, etc. Furthermore, the network 21 may be replaced by a storage medium on which the coded stream Te is recorded, such as a DVD (Digital Versatile Disc: registered trademark) or a BD (Blue-ray Disc: registered trademark).

[0019] The moving image decoding device 31 decodes each of the encoded streams Te transmitted by the network 21 and generates one or more decoded images Td that have been decoded.

[0020] The moving image display device 41 displays all or part of the one or more decoded images Td generated by the moving image decoding device 31. The moving image display device 41 includes, for example, a display device such as a liquid crystal display or an organic EL (Electro-luminescence) display. Examples of the form of the display include stationary, mobile, HMD, etc. Also, when the moving image decoding device 31 has high processing power it displays an image with high image quality, and when it has only lower processing power, it displays an image that does not require high processing power or display ability.

[0021] <Operator> The operators used in this specification are described below.

[0022] >> is a right bit shift, << is a left bit shift, & is a bitwise AND, and | is a bitwise OR |= is an OR assignment operator, and || indicates a logical OR.

[0023] x?y:z is a ternary operator that takes y when x is true (other than 0) and z when x is false (0).

[0024] Clip3(a, b, c) is a function that clips c to a value between a and b, returns a when c < a returns b when c > b, and returns c in other cases (where a <= b).

[0025] abs(a) is a function that returns the absolute value of a.

[0026] ​​​​​floor(a) is a function that returns the largest integer less than or equal to a.

[0028] ceil(a) is a function that returns the smallest integer greater than or equal to a.

[0029] a / d represents the division of a by d (rounded down to the nearest integer).

[0030] <Structure of the coded stream Te> Before proceeding to a detailed description of the video encoding device 11 and video decoding device 31 according to this embodiment, the data structure of the encoded stream Te generated by the video encoding device 11 and decoded by the video decoding device 31 will be described.

[0031] FIG. 4 shows the hierarchical structure of data in the coded stream Te. The frame Te illustratively includes a sequence and a plurality of pictures that make up the sequence. (a) to (f) of FIG. 4 respectively show a coded video sequence that defines the sequence SEQ, a coded picture that defines the picture PICT, a coded slice that defines the slice S, and a slice data. 10 is a diagram showing coded slice data defining data, coding tree units included in the coded slice data, and coding units included in the coding tree units.

[0032] (Coded Video Sequence) In the case of a coded video sequence, a video decoder is used to decode the sequence SEQ to be processed. The sequence SEQ defines a set of data to be referenced by the device 31. As shown in Fig. 4, the sequence SEQ includes a video parameter set, a sequence parameter set SPS (Sequence Parameter Set), a picture parameter set PPS (Picture Parameter Set), an adaptation parameter set (APS), a picture PICT, and supplemental enhancement information SEI (Supplemental Enhancement Information).

[0033] The video parameter set VPS is used to A set of coding parameters common to several video images and a set of coding parameters related to several layers included in the video image and each individual layer are defined.

[0034] The sequence parameter set SPS is used to decode the target sequence. A set of coding parameters to be referenced by the PPS is specified. For example, the width and height of a picture are specified. Note that there may be multiple SPSs. In that case, one of the multiple SPSs can be selected from the PPS. Select .

[0035] The picture parameter set PPS requires the following parameters to be used to decode each picture in the target sequence: A set of coding parameters to be referenced by the video decoding device 31 is defined. For example, the reference value of the quantization width (pic_init_qp_minus26) used in decoding a picture and the application of weighted prediction are specified. It should be noted that there may be multiple PPSs. In this case, one of multiple PPSs is selected from each picture in the target sequence.

[0036] (encoded picture) A coded picture defines a set of data that the video decoding device 31 refers to in order to decode a picture PICT to be processed. As shown in FIG. 4, the picture PICT includes slices 0 to NS-1 (NS is the total number of slices included in the picture PICT).

[0037] In the following, when there is no need to distinguish between slices 0 to NS-1, the symbols The same applies to other data to which subscripts are added that are included in the coded stream Te described below.

[0038] (encoded slice) In the coded slice, the video decoding device 31 refers to the slice S to be processed in order to decode the slice S. As shown in Figure 4, a slice consists of a slice header, and includes slice data.

[0039] The slice header includes a group of coding parameters that the video decoding device 31 refers to in order to determine a decoding method for the current slice. Slice type designation information (slice_type) that designates the slice type is an example of a coding parameter included in the slice header.

[0040] Slice types that can be specified by the slice type specification information include (1) an I-slice that uses only intra-prediction during encoding, (2) a P-slice that uses unidirectional or intra-prediction during encoding, and (3) a B-slice that uses unidirectional, bidirectional, or intra-prediction during encoding. Note that inter-prediction is not limited to uni-prediction or bi-prediction, and a predicted image may be generated using more reference pictures. Hereinafter, P When called a B slice, it is a slice that contains blocks that can use inter prediction. Refers to the s.

[0041] Note that the slice header may include a reference to a picture parameter set PPS (pic_parameter_set_id).

[0042] (encoded slice data) The coded slice data defines a set of data that the video decoding device 31 refers to in order to decode the slice data to be processed. As shown in Fig. 4(d), the slice data includes a CTU. The CTU is a block of a fixed size (for example, 64x64) that constitutes a slice. and is sometimes called the Largest Coding Unit (LCU).

[0043] (coding tree unit) 4 defines a set of data that the video decoding device 31 refers to in order to decode the CTU to be processed. The CTU is decoded by recursive quad tree (QT) partitioning, binary tree (BT) partitioning, or ternary tree (TT) partitioning. The data is divided into coding units (CU), which are the basic units of processing. BT division and TT division are collectively called multi-tree division (MT (Multi Tree) division). The node of the tree structure obtained by recursive quadtree division is called a coding node. The intermediate nodes of the tree are coding nodes, and the CTU itself is also defined as the top coding node. will be done.

[0044] The CT includes, as CT information, a CU split flag (split_cu_flag) indicating whether to split the CT, a QT split flag (split_cu_flag) indicating whether to split the CT, and The flags include a QT split flag (qt_split_cu_flag) indicating whether splitting is performed, an MT split direction (mtt_split_cu_vertical_flag) indicating the split direction of the MT split, and an MT split type (mtt_split_cu_binary_flag) indicating the split type of the MT split. split_cu_flag, qt_split_cu_flag, mtt_split_cu_vertical_flag, and mtt_split_cu_binary_flag are transmitted for each encoding node.

[0045] If split_cu_flag is 1 and qt_split_cu_flag is 1, the coding node splits into four coding nodes. The image is divided into four columns (Fig. 5(b)).

[0046] If split_cu_flag is 0, the coding node is not split and has one CU as a node ( CU is the terminal node of the coding node and is not further divided. CU is the basic unit of the coding process.

[0047] If split_cu_flag is 1 and qt_split_cu_flag is 0, the encoding node will When mtt_split_cu_binary_flag is 1, if mtt_split_cu_vertical_flag is 0, the coding node is split horizontally into two coding nodes (Fig. 5(d)), and if mtt_split_cu_vertical_flag is 1, the coding node is split vertically into two coding nodes (Fig. 5(c)). Also, when mtt_split_cu_binary_flag is 0, if mtt_split_cu_vertical_flag is 0, the coding node is split horizontally into three coding nodes (Fig. 5(f)), and if mtt_split_cu_vertical_flag is 1, the coding node is split vertically into three coding nodes (Fig. 5(e)). These are shown in Fig. 5(g).

[0048] Different trees may be used for luminance and chrominance. The tree type is indicated by treeType. For example, if a common tree is used for luminance (Y, cIdx=0) and chrominance (Cb / Cr, cIdx=1,2), the common single tree is indicated by treeType=SINGLE_TREE. If two different trees (DUAL trees) are used for luminance and chrominance, the luminance tree is indicated by treeType=DUAL_TREE_LUMA and the chrominance tree is indicated by treeType=DUAL_TREE_CHROMA.

[0049] (encoding unit) FIG. 4 shows the data that the video decoding device 31 refers to in order to decode the coding unit to be processed. Specifically, a CU consists of a CU header CUH, prediction parameters, and transformation parameters. The CU header contains information such as prediction mode.

[0050] Prediction processing may be performed in units of CUs, or in units of sub-CUs obtained by further dividing a CU. If the sizes of a CU and a sub-CU are the same, there is one sub-CU in the CU. If the size of a CU is larger than the size of a sub-CU, the CU is divided into sub-CUs. For example, if the CU is 8x8 and the sub-CU is 4x4, the CU is divided into four sub-CUs, divided horizontally by two and vertically by two.

[0051] There are two types of prediction (prediction modes): intra prediction and inter prediction. Intra prediction is a prediction within the same picture, while inter prediction refers to a prediction process performed between different pictures (for example, between display times or between layer images).

[0052] Transformation and quantization processing is performed in units of CU, but quantization coefficients are processed in units of sub-blocks such as 4x4. It may be entropy coded.

[0053] (Prediction parameters) The predicted image is derived from prediction parameters associated with the block, which include intra-prediction and inter-prediction parameters.

[0054] Hereinafter, prediction parameters of inter prediction will be described. The inter prediction parameters are composed of prediction list usage flags predFlagL0 and predFlagL1, reference picture indices refIdxL0 and refIdxL1, and motion vectors mvL0 and mvL1. predFlagL0 and predFlagL1 are flags indicating whether or not a reference picture list (L0 list, L1 list) is used, and when the value is 1, the corresponding reference picture list is used. Note that in this specification, when a "flag indicating whether XX is true" is used, a flag other than 0 (for example, 1) is considered to be XX, and 0 is considered to be not XX, and in logical negation, logical product, etc., 1 is treated as true and 0 is treated as false (the same applies below). However, in an actual device or method, other values ​​may be used as true and false values.

[0055] The syntax elements for deriving inter prediction parameters include, for example, an affine flag affine_flag used in merge mode, a merge flag merge_flag, a merge index merge_idx, an MMVD flag mmvd_flag, and an index for selecting a reference picture used in AMVP mode. Inter prediction identifier inter_pred_idc, reference picture index refIdxLX, predicted vector index mvp_LX_idx for deriving a motion vector, difference vector mvdLX, motion vector There is a precision mode amvr_mode.

[0056] (Reference Picture List) The reference picture list is a list of reference pictures stored in the reference picture memory 306. FIG. 6 is a conceptual diagram showing an example of a reference picture and a reference picture list. In Fig. 6(a), the rectangles represent pictures, the arrows represent picture reference relationships, the horizontal axis represents time, I, P, and B in the rectangles represent intra-pictures, uni-predictive pictures, and bi-predictive pictures, respectively, and the numbers in the rectangles represent decoding. As shown in the figure, the decoding order of the pictures is I0, P1, B2, B3, B4, and the display order is I0, B3, B2, B4, P1. FIG. 6(b) shows an example of a reference picture list for picture B3 (target picture). A reference picture list is a list indicating candidate reference pictures, and one picture (slice) may have one or more reference picture lists. In the example shown in the figure, the target picture B3 has two reference picture lists: an L0 list RefPicList0 and an L1 list RefPicList1. In each CU, the reference picture lists RefPicListX (X=0 or 1) Which picture is actually referenced is specified by refIdxLX. The diagram shows an example where refIdxL0=2 and refIdxL1=0. Note that LX is a notation method used when there is no distinction between L0 prediction and L1 prediction; hereinafter, parameters for the L0 list and parameters for the L1 list will be distinguished by replacing LX with L0 or L1.

[0057] (Merge prediction and AMVP prediction) Prediction parameter decoding (encoding) methods include merge prediction mode and AMVP (Advanced Motion Vector Prediction) mode, and merge_flag is a flag for distinguishing between them. Merge prediction mode is a mode in which the prediction list usage flag predFlagLX, reference picture index refIdxLX, and motion vector mvLX are not included in the encoded data, but are derived from prediction parameters of already processed neighboring blocks, etc. AMVP mode is a mode in which inter_pred_idc, refIdxLX, and mvLX are included in the encoded data. Note that mvLX is encoded as mvp_LX_idx, which identifies the prediction vector mvpLX, and a difference vector mvdLX. In addition to merge prediction mode, affine prediction mode and MMVD prediction mode may also be used.

[0058] inter_pred_idc is a value indicating the type and number of reference pictures, and takes one of the values ​​PRED_L0, PRED_L1, and PRED_BI. PRED_L0 and PRED_L1 are managed by the L0 list and the L1 list, respectively. PRED_BI is managed by the L0 list and the L1 list. This shows bi-prediction using two reference pictures.

[0059] merge_idx is the prediction parameter candidate (merge candidate) derived from the processed block. (Auxiliary) is an index indicating which prediction parameter is to be used as the prediction parameter for the current block.

[0060] (motion vector) mvLX indicates the amount of shift between blocks on two different pictures. The predicted vector and differential vector related to mvLX are called mvpLX and mvdLX, respectively.

[0061] (Inter prediction identifier inter_pred_idc and prediction list usage flag predFlagLX) The relationship between inter_pred_idc, predFlagL0, and predFlagL1 is as follows, and they can be converted to each other.

[0062] inter_pred_idc = (predFlagL1<<1)+predFlagL0 predFlagL0 = inter_pred_idc & 1 predFlagL1 = inter_pred_idc >> 1 Note that the inter prediction parameters may use a prediction list usage flag or an inter prediction identifier. Furthermore, the determination using the prediction list usage flag may be replaced with a determination using the inter prediction identifier. Conversely, the determination using the inter prediction identifier may be replaced with a determination using the prediction list usage flag.

[0063] (Bi-prediction biPred decision) The flag biPred indicating whether or not bi-prediction is performed can be derived based on whether two prediction list usage flags are both 1. For example, it can be derived using the following formula.

[0064] biPred = (predFlagL0==1 && predFlagL1==1) Alternatively, biPred can be derived based on whether the inter prediction identifier is a value indicating the use of two prediction lists (reference pictures). For example, it can be derived using the following formula:

[0065] biPred = (inter_pred_idc==PRED_BI) ? 1 : 0 (Configuration of video decoding device) The configuration of a video decoding device 31 (FIG. 7) according to this embodiment will be described.

[0066] The video decoding device 31 includes an entropy decoding unit 301, a parameter decoding unit (prediction image decoding device ) 302, a loop filter 305, a reference picture memory 306, a prediction parameter memory 307, a prediction image generation unit (prediction image generation device) 308, an inverse quantization and inverse transform unit 311, and an adder 312, a prediction parameter The video encoding device 11 includes a meter derivation unit 320. The image decoding device 31 may also be configured without the loop filter 305 .

[0067] The parameter decoding unit 302 further includes a header decoding unit 3020, a CT information decoding unit 3021, and a CU decoding unit. 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 parameter set information such as VPS, SPS, PPS, and APS, and slice headers (slice information) from the coded data. The CT information decoding unit 3021 decodes the CT from the coded data. The CU decoding unit 3022 decodes the CU from the coded data. The TU decoding unit 3024 extracts QP update information (quantization correction value) and quantization prediction error (residual_coding) from the coded data when a prediction error is included in the TU. Decrypt.

[0068] The TU decoding unit 3024 decodes the QP update information and the quantized prediction error from the coded data when the mode is other than the skip mode (skip_mode==0). More specifically, when skip_mode==0, the TU decoding unit 3024 decodes the flag cu_cbp indicating whether or not the current block contains a quantized prediction error, and decodes the quantized prediction error when cu_cbp is 1. When cu_cbp does not exist in the coded data, In this case, it is derived as 0.

[0069] The TU decoding unit 3024 decodes the index mts_idx indicating the transformation base from the coded data. The TU decoding unit 3024 also decodes an index stIdx, which indicates the use of a secondary transform and the transform base, from the coded data. When stIdx is 0, it indicates that no secondary transform is applied, when it is 1, it indicates one of the transforms in a set (pair) of secondary transform bases, and when it is 2, it indicates one of the transforms in the pair. The other transformation is shown below.

[0070] The TU decoding unit 3024 may also decode a sub-block transform flag cu_sbt_flag. When cu_sbt_flag is 1, the CU is divided into multiple sub-blocks and the residual of only one specific sub-block is decoded. The TU decoding unit 3024 may also decode a flag cu_sbt_quad_flag indicating whether the number of sub-blocks is 4 or 2, cu_sbt_horizontal_flag indicating the division direction, and cu_sbt_pos_flag indicating a sub-block that includes a non-zero transform coefficient.

[0071] The predicted image generating unit 308 includes an inter predicted image generating unit 309 and an intra predicted image generating unit 310. It is composed of:

[0072] The prediction parameter derivation unit 320 includes an inter prediction parameter derivation unit 303 and an intra prediction parameter derivation unit 304 .

[0073] In the following, an example will be described in which CTU and CU are used as processing units, but this is not limitative. Alternatively, the processing may be performed in units of sub-CUs. and processing may be performed in units of blocks or sub-blocks.

[0074] The entropy decoding unit 301 performs entropy decoding on the coded stream Te input from the outside. Entropy coding is performed to decode individual codes (syntax elements). There are two types of entropy coding: one is to use a context (probability model) that is adaptively selected according to the type of syntax element and the surrounding circumstances to variable-length code the syntax elements, and the other is to use a predefined table or formula to variable-length code the syntax elements. The former, CABAC (Context Adaptive Binary Arithmetic Coding), uses the CABAC state (dominant The symbol type (0 or 1) and probability state index (pStateIdx) that specifies the probability are stored in memory. The entropy decoding unit 301 initializes all CABAC states at the beginning of a segment (tile, CTU row, slice). The entropy decoding unit 301 converts the syntax elements into a binary string (bin string) and decodes each bit of the bin string. When a context is used, the entropy decoding unit 301 derives a context index ctxInc for each bit of the syntax element, decodes the bit using the context, and updates the CABAC state of the used context. Bits without context are decoded with equal probability (EP, bypass), and ctxInc is derived and CABAC is performed. The decoded syntax elements include prediction information for generating a predicted image and prediction errors for generating a difference image.

[0075] The entropy decoding unit 301 outputs the decoded code to the parameter decoding unit 302. The decoded code includes, for example, a prediction mode predMode, merge_flag, merge_idx, inter_pred_idc, refIdxLX, mvp_LX_idx, mvdLX, etc. Control of which code to decode is performed based on an instruction from the parameter decoding unit 302.

[0076] (Basic flow) FIG. 8 is a flowchart illustrating the general operation of the video decoding device 31.

[0077] (S1100: Decode Parameter Set Information) The header decoder 3020 decodes parameter set information such as VPS, SPS, and PPS from the coded data.

[0078] (S1200: Decode slice information) The header decoding unit 3020 decodes the slice header from the encoded data. Decode (slice information).

[0079] Hereinafter, the video decoding device 31 performs steps S1300 to S5000 for each CTU included in the target picture. By repeating the above process, a decoded image of each CTU is derived.

[0080] (S1300: Decode CTU Information) The CT information decoding unit 3021 decodes the CTU from the encoded data.

[0081] (S1400: Decode CT Information) The CT information decoding unit 3021 decodes the CT from the encoded data.

[0082] (S1500: CU Decoding) The CU decoding unit 3022 performs S1510 and S1520 to decode the CU from the encoded data. Issued.

[0083] (S1510: Decode CU information) The CU decoding unit 3022 decodes CU information, prediction information, and TU division information from the encoded data. The flag split_transform_flag, the CU residual flags cbf_cb, cbf_cr, cbf_luma, etc. are decoded.

[0084] (S1520: TU information decoding) When a TU includes a prediction error, the TU decoding unit 3024 The QP update information, quantized prediction error, and transformation index mts_idx are decoded from the data. The P update information is derived from the quantization parameter prediction value qPpred, which is the predicted value of the quantization parameter QP. This is the difference value.

[0085] (S2000: Generate predicted image) The predicted image generation unit 308 generates a predicted image for each block included in the current CU based on prediction information.

[0086] (S3000: Inverse Quantization and Inverse Transformation) The inverse quantization and inverse transform unit 311 executes inverse quantization and inverse transform processing on each TU included in the target CU.

[0087] (S4000: Generate decoded image) The adder 312 generates a decoded image using the predicted image supplied from the predicted image generator 308. , and the prediction error supplied from the inverse quantization and inverse transform unit 311 are added to obtain the target CU. A decoded image is generated.

[0088] (S5000: Loop filter) The loop filter 305 applies a loop filter such as a deblocking filter, SAO, or ALF to the decoded image to generate a decoded image.

[0089] (Configuration of the inter-prediction parameter derivation unit) The inter-prediction parameter derivation unit 303 references the prediction parameters stored in the prediction parameter memory 307 based on the syntax elements input from the parameter decoding unit 302. The inter prediction parameter derivation unit 303 and the inter prediction parameter derivation unit 304 output the inter prediction parameters to the inter prediction image generation unit 309 and the prediction parameter memory 307. Its internal elements, the AMVP prediction parameter derivation unit 3032, merge prediction parameter derivation unit 3036, affine prediction unit 30372, MMVD prediction unit 30373, triangle prediction unit 30377, DMVR unit 30537, and MV addition unit 3038, are means common to both video encoding devices and video decoding devices, and may therefore be collectively referred to as a motion vector derivation unit (motion vector derivation device). An example of the inter prediction parameter derivation unit 303 is shown in FIG.

[0090] When affine_flag is 1, that is, when affine prediction mode is indicated, the affine prediction unit 30372 derives inter prediction parameters in units of subblocks.

[0091] When mmvd_flag is 1, that is, when it indicates the MMVD prediction mode, the MMVD predictor 30373 derives inter prediction parameters from the merge candidates and difference vectors derived by the merge prediction parameter derivation unit 3036.

[0092] When triangleFlag is 1, that is, when it indicates triangle prediction mode, the triangle prediction unit 30377 derives triangle prediction parameters.

[0093] If merge_flag is 1, i.e., indicates merge prediction mode, then derive merge_idx and The result is output to the prediction parameter derivation unit 3036.

[0094] When merge_flag is 0, that is, when it indicates the AMVP prediction mode, the AMVP prediction parameter derivation unit 3032 derives mvpLX from inter_pred_idc, refIdxLX, or mvp_LX_idx.

[0095] (MV addition section) The MV adder 3038 adds the derived mvpLX and mvdLX to derive mvLX.

[0096] (Affine prediction part) The affine prediction unit 30372 performs the following steps: 1) estimating two control points CP0 and CP1 of the target block, or three control points CP1 and CP2 of the target block; 2) Derive the motion vectors of the control points CP0, CP1, and CP2, and 3) derive the affine prediction parameters of the target block. 3) Derive the motion vectors for each sub-block from the affine prediction parameters. do.

[0097] In the case of merge affine prediction, the motion vectors cpMvLX[] of each control point CP0, CP1, CP2 are derived from the motion vectors of the blocks adjacent to the target block. The motion vectors of the control points CP0, CP1, and CP2 derived from the motion vector of the block and the coding The cpMvLX[] of each control point is derived from the sum of the difference vectors mvdCpLX[] derived from the data.

[0098] FIG. 11 shows the motion vectors spMvLX of each sub-block that constitutes the target block (cbWidth*cbHeight) as the motion vector cpMvLX[0] of control point CP0, the motion vector cpMvLX[1] of CP1, the motion vector cpMvLX[2] of CP2, and the motion vector spMvLX[3] of control point CP3. 1] is a diagram showing an example of deriving the spMvLX from the vector cpMvLX[2]. The motion vector is derived from the point (xPosCb, yPosCb) located at the center of the block.

[0099] The affine prediction unit 30372 calculates affine prediction parameters for the target block from the motion vectors of the control points. Derive meter(mvScaleHor, mvScalerVer, dHorX, dHorY, dVerX, dVerY).

[0100] mvScaleHor = cpMvLX[0][0] << 7 mvScaleVer = cpMvLX[0][1] << 7 dHorX = (cpMvLX[1][0] - cpMvLX[0][0]) << (7-log2CbW) dVerX = (cpMvLX[1][1] - cpMvLX[0][1]) << (7-log2CbW) If numCpMv==3, dHorY = (cpMvLX[2][0] - cpMvLX[0][0]) << (7 - log2CbH) dVerY = (cpMvLX[2][1] - cpMvLX[0][1]) << (7 - log2CbH) If numCpMv!=3, dHorY = - dVerX dVerY = dHorX Here, log2CbW and log2CbH are the logarithmic values ​​of the width cbWidth and height cbHeight of the target block. do.

[0101] The affine prediction unit 30372 predicts the affine prediction parameters of the target block based on the affine prediction parameters of the target block. The locked spMvLX[i][j] (i=0,1,2,...,(cbWidth / sbWidth)-1, j=0,1,2,...,(cbHeight / sbHeight)-1) is calculated using the following formula:

[0102] xPosCb = 2 + (i<<2) yPosCb = 2 + (j<<2) spMvLX[i][j][0] = mvScaleHor + dHorX * xPosCb + dHorY * yPosCb spMvLX[i][j][1] = mvScaleVer + dVerX * xPosCb + dVerY * yPosCb Further round shifting and clipping may be performed.

[0103] spMvLX[i][j][0] = Clip3(-2^17, 2^17, (spMvLX[i][j][0]+64)>>7 ) spMvLX[i][j][1] = Clip3(-2^17, 2^17, (spMvLX[i][j][1]+64)>>7 ) Here, sbWidth and sbHeight are the width and height of the target sub-block.

[0104] Furthermore, at the upper left coordinate (xSb, ySb) of the sub-block, spMvLX[i][j] is assigned to the corresponding mvLX in the screen, where x = 0..sbWidth-1, y = 0..sbHeight-1.

[0105] mvLX[xSb + x][yXb + y] = spMv[i][j] (PROF) PROF (Prediction Refinement with Optical Flow) is a method to estimate pixel levels based on pixel gradient information. This method calculates Bell optical flow and modifies affine prediction at the sub-block level.

[0106] Specific processing performed by the BIO unit 30954 will be described with reference to Fig. 12. The BIO unit 30954 includes an L0, L1 predicted image generation unit 309541, a gradient image generation unit 309542, a correlation parameter calculation unit 309543, a motion compensation correction value derivation unit 309544, and a bidirectional predicted image generation unit 309545. The BIO unit 30954 generates a predicted image from the interpolated image received from the motion compensation unit 3091 and the inter prediction parameters received from the inter prediction parameter decoding unit 303, and outputs the generated predicted image to the adder 312. The process of deriving the motion compensation correction value bdofOffset (motion compensation correction image) from the gradient image and correcting and deriving PredL0 and PredL1 is called bidirectional gradient change processing.

[0107] First, the variable cbProfFlagLX indicating the application condition of PROF is derived as follows.

[0108] cbProfFlagLX is set to FALSE if one or more of the following conditions are true:

[0109] numCpMv is equal to 2, cpMvLX[1][0] is equal to cpMvLX[0][0], and cpMvLX[1][1] is equal to cpMvLX[0][1].

[0110] ·numCpMv is equal to 3, cpMvLX[1][0] is equal to cpMvLX[0][0], cpMvLX[1][1] is equal to cpMvLX[0][1] and cpMvLX[2][0] is equal to cpMvLX[0][0], and cpMvLX[2][1] is equal to cpMvLX[0][1].

[0111] Generally, to obtain optical flow, it is assumed that the luminance is constant. However, in Non-Patent Document 1, this assumption is not taken into consideration in the application conditions of PROF. Therefore, in this embodiment, the conditions for setting cbProfFlagLX to FALSE are as follows: In addition to the conditions, bcwIdx[xCb][yCb] is not 0 (it is not the default weighting coefficient). luma_weight_lX_flag[refIdxLX] is 1. (Weight prediction weight coefficient is applied.) ) (Note that X is 0 for L0 prediction and 1 for L1 prediction.) This allows the adoption of prediction methods that respond to brightness fluctuations (BCW prediction and weighted prediction). If this is the case, the issue can be resolved by adding a condition that PROF is not selected.

[0112] Otherwise, cbProfFlagLX is set to TRUE.

[0113] 13 is a flowchart illustrating the process of this embodiment. In FIG. 13(a), after the affine prediction process (S2001), it is checked whether BcwIdx[xCb][yCb] is 0 (S2002). If it is 0, PROF 13B shows an example in which, after the affine prediction process (S2004), it is checked whether luma_weight_lX_flag[refIdxLX] is 1 (S2005). If it is 1, the PROF process is skipped. If it is 0, the PROF process is executed (S2006). This shows an example of executing

[0114] If cbProfFlagLX is TRUE, the motion vector difference array diffMv is derived as follows.

[0115] First, the variables sbWidth, sbHeight, dmvLimit, posOffsetX and posOffsetY are as follows: It is derived as follows.

[0116] sbWidth = cbWidth / numSbX sbHeight = cbHeight / numSbY dmvLimit = 1 << Max(6, BitDepthY - 6) posOffsetX = 6 * dHorX + 6 * dVerX posOffsetY = 6 * dHorY + 6 * dVerY For x = 0..sbWidth - 1 and y = 0..sbHeight - 1, apply the following:

[0117] diffMv[x][y][0] = x *(dHorX << 2)+ y *(dVerX << 2)- posOffsetX diffMv[x][y][1] = x *(dHorY << 2)+ y *(dVerY << 2)- posOffsetY Furthermore, for i = 0..1, diffMv[x][y][0] =(diffMv[x][y][0] + 64 -(diffMv[x][y][0] >= 0))>> 7 diffMv[x][y][1] =(diffMv[x][y][1] + 64 -(diffMv[x][y][1] >= 0))>> 7 The values ​​of diffMv[x][y][i] are clipped as follows:

[0118] diffMv[x][y][i] = Clip3(-dmvLimit, dmvLimit-1, diffMv[x][y][i]) Using the diffMV thus obtained, the optical flow at the pixel level is calculated based on the gradient information of the affine prediction at the sub-block level, and the predicted sample value is corrected at the pixel level.

[0119] In Non-Patent Document 1, the variable dmvLimit indicating the range in which the value of diiffMV is clipped is 1. << Although it is set to Max(6, BitDepthY - 6), the range of the motion vector is actually the pixel This value should not depend on the bit length. Also, there is a problem that the precision of the calculation of the predicted sample, which will be described later, exceeds 16 bits. Therefore, in this embodiment, dmvLimit = 32 Or, dmvLimit = 16 This will be implemented with a fixed value.

[0120] Next, two variables sbWidth and sbHeight that specify the width and height of the current sub-block, a predicted sample array predSamples of (sbWidth + borderExtension)*(sbHeight + borderExtension), and a motion vector difference array diffMv of (sbWidth * sbHeight) are input. The variable shift1 is set to 6.

[0121] If x = 0..sbWidth-1, then y = 0..sbHeight-1, then the next ordered step is Applies. - The variables gradientH[x][y] and gradientV[x][y] used to calculate the gradient are derived as follows:

[0122] gradientH[x][y] =(predSamples[x + 2][y] >> shift1) -(predSamples[x][y] >> shift1) gradientV[x][y] =(predSamples[x][y + 2] >> shift1) -(predSamples[x][y] >> shift1) The variable dI is derived as follows.

[0123] dI = gradientH[x][y] * diffMv[x][y][0] + gradientV[x][y] * diffMv[x][y][1] The predicted sample value at the position (x, y) in the sub-block is derived as follows, and a (sbWidth) x (sbHeight) array pbSamples of the predicted sample values ​​is output.

[0124] pbSamples[x][y] = predSamples[x + 1][y + 1] +((dI + 1)>> 1) (Merge prediction) FIG. 10(a) is a schematic diagram showing the configuration of the merge prediction parameter derivation unit 3036 according to this embodiment. The merge prediction parameter derivation unit 3036 includes a merge candidate derivation unit 30361 and a merge candidate selection unit 30362. Note that merge candidates are configured to include prediction parameters (predFlagLX, mvLX, refIdxLX, bcwIdx) and are stored in a merge candidate list. Merge candidates stored in the merge candidate list are assigned indices according to a predetermined rule.

[0125] The merge candidate derivation unit 30361 directly combines the motion vectors and refIdxLX of the decoded neighboring blocks. In addition, the merge candidate derivation unit 30361 uses the spatial Merge candidate derivation processes, temporal merge candidate derivation processes, pairwise merge candidate derivation processes, and zero merge candidate derivation processes may be applied.

[0126] As a spatial merge candidate derivation process, the merge candidate derivation unit 30361 predicts merge candidates according to a predetermined rule. The predicted parameters stored in the measurement parameter memory 307 are read out and set as merge candidates. The reference pictures are specified, for example, by prediction parameters for each of the adjacent blocks within a predetermined range from the target block (for example, all or part of the blocks adjacent to the left A1, right B1, upper right B0, lower left A0, and upper left B2 of the target block). The merge candidates are called A1, B1, B0, A0, and B2. Here, A1, B1, B0, A0, and B2 are motion information derived from blocks containing the following coordinates: Figure 10(b) shows the positions of A1, B1, B0, A0, and B2.

[0127] A1: (xCb - 1, yCb + cbHeight - 1) B1: (xCb + cbWidth - 1, yCb - 1) B0: (xCb + cbWidth, yCb - 1) A0: (xCb - 1, yCb + cbHeight) B2: (xCb - 1, yCb - 1) The upper left coordinates of the target block are (xCb, yCb), the width is cbWidth, and the height is cbHeight.

[0128] In the temporal merge derivation process, the merge candidate derivation unit 30361 calculates the prediction parameters of the block C in the reference image including the coordinates of the lower right CBR or the center of the target block from the prediction parameter menu. The merge candidates are read from memory 307 and stored as merge candidates Col in the merge candidate list mergeCandList[]. do.

[0129] The pairwise candidate derivation unit derives a pairwise candidate avgK from the average of the two merge candidates (p0Cand, p1Cand) already stored in mergeCandList, and stores it in mergeCandList[].

[0130] mvLXavgK[0] = (mvLXp0Cand[0]+mvLXp1Cand[0]) / 2 mvLXavgK[1] = (mvLXp0Cand[1]+mvLXp1Cand[1]) / 2 The merge candidate derivation unit 30361 determines whether refIdxLX is 0...M and whether the X and Y components of mvLX are both 0. The zero merge candidates Z0,...,ZM are derived and stored in a merge candidate list.

[0131] The order of storing merge candidates in mergeCandList[] is, for example, spatial merge candidates (A1, B1, B0, A0, B2), time The merge candidate Col, the pairwise candidate avgK, and the zero merge candidate ZK. Note that The reference block (e.g., the block is intra-predicted) is not stored in the merge candidate list. i = 0 if( availableFlagA1 ) mergeCandList[ i++ ] = A1 if( availableFlagB1 ) mergeCandList[ i++ ] = B1 if( availableFlagB0 ) mergeCandList[ i++ ] = B0 if( availableFlagA0 ) mergeCandList[ i++ ] = A0 if( availableFlagB2 ) mergeCandList[ i++ ] = B2 if( availableFlagCol ) mergeCandList[ i++ ] = Col if( availableFlagAvgK ) mergeCandList[ i++ ] = avgK if( i < MaxNumMergeCand ) mergeCandList[ i++ ] = ZK The merge candidate selection unit 30362 selects a merge candidate N indicated by merge_idx from among the merge candidates included in the merge candidate list using the following formula.

[0132] N = mergeCandList[merge_idx] Here, N is a label indicating a merge candidate, and takes A1, B1, B0, A0, B2, Col, avgK, ZK, etc. The motion information of the merge candidate indicated by label N is indicated by (mvLXN[0], mvLXN[0]), predFlagLXN, refIdxLXN, and bcwIdxN.

[0133] Selected (mvLXN[0], mvLXN[0]), predFlagLXN, refIdxLXN, bcwIdxN as the target block The merge candidate selection unit 30362 selects the selected merge candidate as an inter prediction parameter. The candidate inter-prediction parameters are stored in a prediction parameter memory 307, and the inter-prediction parameters are stored in a prediction parameter memory 308. - The predicted image is output to the predicted image generation unit 309.

[0134] (MMVD Prediction Section 30373) The MMVD prediction unit 30373 predicts the center vector mvpLX (merge candidate) derived by the merge candidate derivation unit 30361. The motion vector mvLX is obtained by adding mvdLX of a predetermined distance and a predetermined direction to the motion vector mvLX (complement N). The MMVD prediction unit 30373 calculates the syntax element base_candidate_idx of the coded data. The center vector mvLX[] is derived using the direction_idx, which indicates the index of the direction table. The difference vector mMvdLX[] is derived from distance_idx, which indicates the index of the distance table.

[0135] (Triangle forecast) In Triangle prediction, as shown in Figure 17, the target block is divided into two parts using two types of diagonal lines. The image is divided into triangular prediction units (PU0, PU1). In the figure, (a) shows the division direction triangleDir=0, and (b) shows triangleDir=1. After generating the predicted images for PU0 and PU1, weighting processing is performed on the diagonal edges.

[0136] Operations other than prediction (eg, transformation and quantization) are applied to the entire block.

[0137] (Syntax decoding) Triangle prediction on / off and parameters for on are notified in the encoded data as follows:

[0138] sps_triangle_enabled_flag is notified by SPS and indicates whether or not the Triangle prediction mode is used in the target sequence. When sps_triangle_enabled_flag is 0, it indicates that the Triangle prediction mode is not used in the target sequence, and when sps_triangle_enabled_flag is 1, it indicates that the Triangle prediction mode is used in the target sequence.

[0139] (Motion information derivation process) The triangle prediction unit 30377 determines the merge indexes m and n of PU0 and PU1, the division method of triangle prediction, and Derive the direction triangleDir.

[0140] m = merge_triangle_idx0 n = merge_triangle_idx1 + (merge_triangle_idx1 >= m) ? 1 : 0 triangleDir = merge_triangle_split_dir In the following, we denote the merge candidate pointed to by merge index m as M, and the merge candidate pointed to by merge index n as M. The candidate is denoted as N.

[0141] The merge prediction parameter derivation unit 3036 calculates the motion information (mvLXM, mvLXN, refIdxLXM, refIdxLXN, predFlagLXM, predFlagLXN, bcwIdxN) of merge candidates M and N using the method described in (Merge Prediction). , bcwIdxN, mergeCandList, etc.) are derived. The motion vectors mvA and mvB, reference indices refIdxA and refIdxB, and prediction list flags predListFlagA and predListFlagB of PU0 and PU1 are set using the formula:

[0142] mvA[0] = mvLXM[0] mvA[1] = mvLXM[1] refIdxA = refIdxLXM predListFlagA = X Here, the lowest 1 bit of m is set to X (m & 0x01). Note that if predFlagLXM is 0, X is set to (1-X).

[0143] mvB[0] = mvLXN[0] mvB[1] = mvLXN[1] refIdxB = refIdxLXN predListFlagB = X Here, the lowest 1 bit of n is set to X (n & 0x01). If predFlagLXN is 0, X is set to (1-X).

[0144] These pieces of motion information are referenced to generate predicted images for PU0 and PU1.

[0145] (Deriving weighting coefficients for triangle mode) The triangle prediction unit 30377 calculates the weight prediction coefficient to be applied to the diagonal edge of the boundary between PU0 and PU1. The numbers are derived using the following procedure, where nCbW=cbWidth and nCbH=cbHeight.

[0146] A variable nCbR representing the shape of the target block is derived.

[0147] nCbR = (nCbW > nCbH) ? (nCbW / nCbH) : (nCbH / nCbW) When triangleDir is 0, the weighting coefficient wValue of the predicted pixel is derived as follows:

[0148] wValue = (nCbW > nCbH) ? (Clip3(0, 8, (x / nCbR - y) + 4)) : (Clip3(0, 8, (x - y / nCbR) + 4)) If triangleDir is 1, derive wValue as follows:

[0149] wValue = (nCbW > nCbH) ? (Clip3(0, 8, (nCbH - 1 - x / nCbR - y) + 4)) : (Clip3(0, 8, (nCbW - 1 - x - y / nCbR) + 4)) An example of wValue is shown in FIG.

[0150] (Triangle mode motion vector storage processing) The triangle prediction unit 30377 calculates the values ​​of PU0 and PU1 in the following manner so that they can be referenced in subsequent processing. Motion information is stored in memory in 4*4 sub-block units.

[0151] numSbX and numSbY are the numbers of 4*4 sub-blocks in the horizontal and vertical directions of the target block. , set numSbX = cbWidth >> 2, numSbY = cbHeight >> 2. minSb = min(numSbX, numSbY).

[0152] Derive the block aspect ratio cbRatio.

[0153] cbRatio = (cbWidth > cbHeight) ? (cbWidth / cbHeight) : (cbHeight / cbWidth) For each position (xSbIdx, ySbIdx) of a 4*4 sub-block where xSbIdx = 0..numSbX - 1 and ySbIdx = 0..numSbY - 1, the following process is performed.

[0154] Using (xSbIdx, ySbIdx), xIdx and yIdx are derived.

[0155] xIdx = (cbWidth > cbHeight) ? (xSbIdx / cbRatio) : xSbIdx yIdx = (cbWidth > cbHeight) ? ySbIdx : (ySbIdx / cbRatio) When triangleDir==0, sType shown in FIG. 17(e) is derived as follows:

[0156] sType = (xIdx == yIdx) ? 2 : ((xIdx > yIdx) ? 0 : 1) When triangleDir==1, sType shown in FIG. 17(f) is derived as follows:

[0157] sType = (xIdx + yIdx == minSb) ? 2 : ((xIdx + yIdx < minSb) ? 0 : 1) sType is a parameter that indicates whether each 4*4 sub-block is located in PU0, PU1, or the boundary between PU0 and PU1. sType=0 indicates that the 4*4 sub-block is located in PU0. sType=1 indicates that the 4*4 sub-block is located in PU1. sType=2 indicates that the 4*4 sub-block is located on the boundary between PU0 and PU1.

[0158] If sType==0, do the following:

[0159] If the prediction list flag of PU0 is 0 (predListFlagA==0), PU0 is assumed to be unidirectionally predicted from L0, and if the prediction list flag of PU0 is not 0 (predListFlagA!=0), motion information is stored assuming that PU0 is unidirectionally predicted from L1.

[0160] predFlagL0 = (predListFlagA == 0) ? 1 : 0 predFlagL1 = (predListFlagA == 0) ? 0 : 1 refIdxL0 = (predListFlagA == 0) ? refIdxA : -1 refIdxL1 = (predListFlagA == 0) ? -1 : refIdxA mvL0[0] = (predListFlagA == 0) ? mvA[0] : 0 mvL0[1] = (predListFlagA == 0) ? mvA[1] : 0 mvL1[0] = (predListFlagA == 0) ? 0 : mvA[0] mvL1[1] = (predListFlagA == 0) ? 0 : mvA[1] Otherwise, if sType==1, or sType==2 and predListFlagA+predListFlagB!=1, then do the following: where predListFlagA+predListFlagB!=1 indicates that the reference picture lists of PU0 and PU1 are the same.

[0161] If the prediction list flag of PU1 is 0 (predListFlagB==0), PU1 is L0 predicted (unidirectional prediction). If the prediction list flag of PU1 is not 0 (predListFlagB!=0), PU1 is used for L1 prediction (unidirectional prediction). The motion information is stored as a timestamp.

[0162] predFlagL0 = (predListFlagB == 0) ? 1 : 0 predFlagL1 = (predListFlagB == 0) ? 0 : 1 refIdxL0 = (predListFlagB == 0) ? refIdxB : -1 refIdxL1 = (predListFlagB == 0) ? -1 : refIdxB mvL0[0] = (predListFlagB == 0) ? mvB[0] : 0 mvL0[1] = (predListFlagB == 0) ? mvB[1] : 0 mvL1[0] = (predListFlagB == 0) ? 0 : mvB[0] mvL1[1] = (predListFlagB == 0) ? 0 : mvB[1] Otherwise (sType==2 and predListFlagA+predListFlagB==1), do the following: Here, predListFlagA+predListFlagB==1 indicates that the reference picture lists of PU0 and PU1 are different.

[0163] If the prediction list flag for PU0 is 0 (predListFlagA==0), bidirectional prediction is set with PU0 information stored in L0 and PU1 information stored in L1. If the prediction list flag for PU0 is not 0 (predListFlagA!=0), bidirectional prediction is set with PU1 information stored in L0 and PU0 information stored in L1.

[0164] predFlagL0 = 1 predFlagL1 = 1 refIdxL0 = (predListFlagA == 0) ? refIdxA : refIdxB refIdxL1 = (predListFlagA == 0) ? refIdxB : refIdxA mvL0[0] = (predListFlagA == 0) ? mvA[0] : mvB[0] mvL0[1] = (predListFlagA == 0) ? mvA[1] : mvB[1] mvL1[0] = (predListFlagA == 0) ? mvB[0] : mvA[0] mvL1[1] = (predListFlagA == 0) ? mvB[1] : mvA[1] (DMVR) Next, a description will be given of a DMVR (Decoder-side Motion Vector Refinement) process performed by the DMVR unit 30375. When merge_flag is 1 for a target CU or when the skip flag skip_flag is 1, the DMVR unit 30375 calculates the mvLX of the target CU derived by the merge prediction unit 30374 from the reference image. Specifically, the prediction parameters derived by the merge prediction unit 30374 are bi-predictive. In the case where the motion vector is estimated, the motion vector is corrected using a predicted image derived from the motion vectors corresponding to two reference pictures. The corrected mvLX is output to the inter predicted image generating unit 309. are supplied to.

[0165] (AMVP forecast) FIG. 10(c) is a schematic diagram showing the configuration of the AMVP prediction parameter derivation unit 3032 according to this embodiment. The AMVP prediction parameter derivation unit 3032 includes a vector candidate derivation unit 3033 and a vector candidate selection unit 3034. The vector candidate derivation unit 3033 selects a vector candidate from the prediction parameter memory 307 based on refIdxLX. The prediction vector candidate is derived from the motion vector of the adjacent block that has already been decoded and stored in the prediction vector candidate list mvpListLX[ ].

[0166] The vector candidate selection unit 3034 selects the vector candidate mvp_LX_idx from the prediction vector candidates in mvpListLX[]. The vector candidate selection unit 3034 outputs the selected mvpLX to the MV addition unit 3038.

[0167] (MV addition section) The MV addition unit 3038 calculates mvLX by adding the mvpLX input from the AMVP prediction parameter derivation unit 3032 and the decoded mvdLX. The addition unit 3038 outputs the calculated mvLX to the inter predicted image generation unit 309. and outputs it to the prediction parameter memory 307.

[0168] mvLX[0] = mvpLX[0]+mvdLX[0] mvLX[1] = mvpLX[1] + mvdLX[1] (Motion Vector Scaling) A method for deriving the scaling of a motion vector will be described. A motion vector Mv (reference motion vector), a picture PicMv including a block having Mv, a reference picture PicMvRef of Mv, and a scaling vector are used. The motion vector sMv after the block is moved, the picture CurPic containing the block with sMv, and the reference picture referenced by sMv. Given a picture CurPicRef, the derivative function of sMv, MvScale(Mv, PicMv, PicMvRef, CurPic, CurPicRef), is expressed by the following equation.

[0169] sMv = MvScale(Mv,PicMv,PicMvRef,CurPic,CurPicRef) = Clip3(-R1,R1-1,sign(distScaleFactor*Mv)*((abs(distScaleFactor*Mv)+round1-1)>>shift1)) distScaleFactor = Clip3(-R2,R2-1,(tb*tx+round2)>>shift2) tx = (16384+abs(td)>>1) / td td = DiffPicOrderCnt(PicMv,PicMvRef) tb = DiffPicOrderCnt(CurPic,CurPicRef) Here, round1, round2, shift1, and shift2 are round and shift values ​​for division using reciprocals, for example, round1=1<<(shift1-1), round2=1<<(shift2-1), shift1=8, and shift2=6. DiffPicOrderCnt(Pic1,Pic2) is the time information (e.g., POC) of Pic1 and Pic2. This is a function that returns the difference between the two. R1 and R2 are used to limit the range of values ​​in order to perform processing with limited precision, for example, R1 = 32768, R2 = 4096, etc.

[0170] In addition, the scaling function MvScale(Mv, PicMv, PicMvRef, CurPic, CurPicRef) is expressed by the following formula: Good too.

[0171] MvScale(Mv,PicMv,PicMvRef,CurPic,CurPicRef) = Mv*DiffPicOrderCnt(CurPic,CurPicRef) / DiffPicOrderCnt(PicMv,PicMvRef) That is, Mv may be scaled according to the ratio between the difference in time information between CurPic and CurPicRef and the difference in time information between PicMv and PicMvRef.

[0172] (Configuration of the intra-prediction parameter derivation unit 304) The intra-prediction parameter derivation unit 304 derives intra-prediction parameters by referring to the prediction parameters stored in the prediction parameter memory 307 based on the input from the parameter decoding unit 302. For example, the intra prediction mode IntraPredMode is derived. The unit 304 outputs the intra prediction parameters to a predicted image generation unit 308 and stores them in a prediction parameter memory 307. The intra prediction parameter derivation unit 304 may derive different intra prediction modes for luma and chroma.

[0173] The loop filter 305 is a filter provided in the encoding loop, and is used to remove block distortion and ringing. The loop filter 305 is a filter that removes distortion and improves image quality. The loop filter 305 applies a deblocking filter, a sample adaptive offset (SAO), and an adaptive filter to the decoded image of the CU generated by the adder 312. Apply a filter such as an adaptive loop filter (ALF).

[0174] The reference picture memory 306 stores the decoded image of the CU in a predetermined format for each target picture and target CU. Store in the location.

[0175] The prediction parameter memory 307 stores prediction parameters at a predetermined location for each CTU or CU. Specifically, the prediction parameter memory 307 stores parameters decoded by the parameter decoding unit 302, parameters derived by the prediction parameter derivation unit 320, and the like.

[0176] The predicted image generation unit 308 receives the parameters derived by the prediction parameter derivation unit 320. The predicted image generation unit 308 also reads a reference picture from the reference picture memory 306. The predicted image generation unit 308 generates a prediction image based on the parameters and the reference picture (reference picture A reference picture block is a set of pixels (usually rectangular, hence the name block) on the reference picture, and is the area referenced to generate a predicted image.

[0177] (Inter-prediction image generation unit 309) When predMode indicates an inter prediction mode, the inter predicted image generation unit 309 Using the inter-prediction parameters and reference pictures input from the prediction parameter derivation unit 303, A predicted image of the block or sub-block is generated by inter-prediction.

[0178] FIG. 14 is a schematic diagram showing the configuration of an inter-prediction image generation unit 309 included in the prediction image generation unit 308 according to this embodiment. The inter-prediction image generation unit 309 is a motion compensation unit (prediction image generation device). The synthesis unit 3095 includes an IntraInter synthesis unit 30951, a Triangle synthesis unit 30952, a BDOF unit 30954, a weighted prediction unit 3094, and a PROF unit 30955.

[0179] (motion compensation) The motion compensation unit 3091 (interpolated image generation unit 3091) receives the input from the inter prediction parameter derivation unit 303. Based on the input inter prediction parameters (predFlagLX, refIdxLX, mvLX), an interpolated image (motion compensated image) is generated by reading reference blocks from the reference picture memory 306. The reference block is a block located at a position shifted by mvLX from the position of the current block on the reference picture RefPicLX specified by refIdxLX. If mvLX does not have integer precision, an interpolated image is generated by applying a filter called a motion compensation filter, which generates pixels at decimal positions.

[0180] The motion compensation unit 3091 first derives the integer position (xInt, yInt) and phase (xFrac, yFrac) corresponding to the coordinates (x, y) in the prediction block using the following equations.

[0181] xInt = xPb+(mvLX[0]>>(log2(MVPREC)))+x xFrac = mvLX[0]&(MVPREC-1) yInt = yPb+(mvLX[1]>>(log2(MVPREC)))+y yFrac = mvLX[1]&(MVPREC-1) Here, (xPb, yPb) is the top left coordinate of a block of size cbWidth*cbHeight, x=0...cbWidth-1 , y=0...cbHeight-1, and MVPREC indicates the precision of mvLX (1 / MVPREC pixel precision). For example, MVPREC=16.

[0182] The motion compensation unit 3091 derives the temporary image temp[][] by performing horizontal interpolation on the reference picture refImg using an interpolation filter. In the following, Σ is the sum over k, where k=0..NTAP-1, shift1 is a normalization parameter that adjusts the value range, and offset1=1<<(shift1-1).

[0183] temp[x][y] = (ΣmcFilter[xFrac][k]*refImg[xInt+k-NTAP / 2+1][yInt]+offset1)>>shift1 Next, the motion compensation unit 3091 derives the interpolated image Pred[][] by vertically interpolating the temporary image temp[][]. In the following, Σ is the sum for k=0..NTAP-1, shift2 is a normalization parameter that adjusts the value range, and offset2=1<<(shift2-1).

[0184] Pred[x][y] = (ΣmcFilter[yFrac][k]*temp[x][y+k-NTAP / 2+1]+offset2)>>shift2 In the case of bi-prediction, the above Pred[][] is derived for each L0 list and L1 list (called interpolated images PredL0[][] and PredL1[][]), and the interpolated image Pred[][] is generated from PredL0[][] and PredL1[][].

[0185] The synthesis unit 3095 includes an IntraInter synthesis unit 30951 , a Triangle synthesis unit 30952 , a weighted prediction unit 3094 , and a BDOF unit 30954 .

[0186] (IntraInter synthesis processing) The IntraInter synthesis unit 30951 performs weighted summation of the inter-predicted image and the intra-predicted image. A predicted image is generated.

[0187] (Triangle synthesis processing) When MergeTriangleFlag is 1, the triangle synthesis unit 30952 generates the predicted image pbSamples.

[0188] In the following, pbSamples is a prediction block of size cbWidth*cbHeight. predSamplesLA and predSamplesLB are prediction images generated by the motion compensation unit 3091 using motion information of PU0 and PU1. be.

[0189] The triangle synthesis unit 30952 generates pbSamples according to triangleDir. In , weighted prediction processing is applied to the diagonal edge of the boundary between PU0 and PU1 using wValue using the following equation.

[0190] pbSamples[x][y] = Clip3(0, (1 << bitDepth) - 1, (predSamplesLA[x][y] * wValue + predSamplesLB[x][y] * (8 - wValue) + offset1) >> shift1) where shift1 = Max(5, 17 - bitDepth) and offset1 = 1 << (shift1 - 1).

[0191] The problem with the above formula is that the value of shift1 is incorrect as a prediction formula. In this embodiment, taking into consideration that the maximum value of wValue is 8, the above problem is solved by using shift1 = Max(6, 18 - bitDepth).

[0192] Another problem with Non-Patent Document 1 is that it does not explicitly state how to perform triangle synthesis processing when weighted prediction is applied. Triangle prediction is a merge mode, so it can only be switched on and off on a slice-by-slice basis. Therefore, PPS If pps_weighted_pred_flag or pps_weighted_bipred_flag is 1, Triangle pre- There are also methods that do not perform weighted prediction, or methods that do not apply weighted prediction even if weighting factors exist in the case of triangle prediction. However, both of these methods have problems in terms of coding efficiency.

[0193] Therefore, in this embodiment, the following weighted prediction process is performed on the predicted images predSamplesLA and predSamplesLB, and then triangle synthesis process is performed.

[0194] predSamplesLA[x][y] = Clip3(0,(1< <Max(14, bitDepth+2)-1, ((PredsampleLA[x][y]*w0+(1<<(log2WD-1))>>log2WD)+o0) predSamplesLB[x][y] = Clip3(0,(1< <Max(14, bitDepth+2)-1, ((PredsampleLB[x][y]*w1+(1<<(log2WD-1))>>log2WD)+o1) pbSamples[x][y] = Clip3(0, (1 << bitDepth) - 1, (predSamplesLA[x][y] * wValue + predSamplesLB[x][y] * (8 - wValue) + offset1) >> shift1) where shift1 = Max(6, 18 - bitDepth) and offset1 = 1 << (shift1 - 1).

[0195] In this way, by generating an interpolated image that has been subjected to weighted prediction processing in advance and then performing triangle synthesis processing, triangle prediction can be performed efficiently even when the brightness fluctuates, such as in a faded image.

[0196] In another embodiment, a weighted prediction process, described below, is performed on two predicted images predSamplesLA and predSamplesLB according to refIdxA and refIdxB to generate a predicted image with a pixel bit length of bitDepth, and then triangular synthesis processing is performed as follows.

[0197] pbSamples[x][y] = (predSamplesLA[x][y] * wValue + predSamplesLB[x][y] * (8 - wValue) + 4) >> 3 In this way, by generating a predicted image that has undergone weighted prediction processing in advance and then performing triangle synthesis processing, triangle prediction can be performed efficiently even when brightness fluctuates, such as in faded images. In the above-described method, it is necessary to specially generate an interpolated image that has undergone weighted prediction processing, but in this embodiment, triangle synthesis processing can be performed after normal weighted prediction processing.

[0198] 18 is a diagram illustrating the triangulation synthesis unit 30952 of this embodiment, which receives motion compensation information from the motion compensation unit 3091 and outputs a predicted image to the addition unit 312. The triangulation synthesis unit 30952 generates an L0 default predicted image from an L0 weighted predicted image generator 309521, an L0 weighted predicted image generator 309522, and an L1 default predicted image. The image generation unit 309523, an L1 weighted predicted image generation unit 309524, and a triangle predicted image generation unit 309525. The predicted images predSamplesLA and predSamplesLB are associated with L0 prediction and L1 prediction, and default prediction or weighted prediction is selected depending on whether a weighting coefficient is present. After processing, the triangle predicted image generation unit 309525 performs synthesis processing of the triangle prediction.

[0199] (BDOF prediction) In bi-prediction mode, the BDOF unit 30954 generates two predicted images (a first predicted image and a second predicted image). A predicted image is generated by referring to the predicted image and the gradient correction term.

[0200] When the inter-prediction parameter decoding unit 303 determines that the L0 unidirectional prediction is used, the motion compensation unit 3091 generates PredL0[x][y]. The inter-prediction parameter decoding unit 303 determines that L1 is unidirectional prediction. On the other hand, if the inter prediction parameter decoding unit 303 determines that the mode is bi-prediction, the following processing is performed. If bdofAvailableFlag indicates TRUE, the BDOF unit 30954 executes BDOF processing to generate a bidirectionally predicted image, and if it indicates FALSE, the synthesis unit 3095 generates a predicted image using normal bidirectionally predicted image generation.

[0201] (Weight prediction) The weighted prediction unit 3094 generates a predicted image pbSamples of the block from the interpolated image PredLX. First, the syntax related to the weight prediction unit 3094 will be explained.

[0202] FIG. 19(a) shows an example of the syntax of sps_weighted_pred_flag and sps_weighted_bipred_flag in a Sequence Parameter Set (SPS).

[0203] sps_weighted_pred_flag equal to 1 indicates that weighted prediction is applied to P slices that refer to the SPS. sps_weighted_pred_flag equal to 0 indicates that weighted prediction is not applied to P slices that reference an SPS. sps_weighted_bipred_flag equal to 1 indicates that weighted prediction may be applied to B slices that reference an SPS. sps_weighted_bipred_flag equal to 0 indicates that weighted prediction is not applied to B slices that reference an SPS. Indicates that it does not apply.

[0204] FIG. 19(b) shows an example of the syntax of pps_weighted_pred_flag and pps_weighted_bipred_flag in the Picture Parameter Set (PPS).

[0205] pps_weighted_pred_flag equal to 0 means that weighted prediction is applied to the P slices that refer to the PPS. pps_weighted_pred_flag equal to 1 indicates that the PPS that refers to the PPS is not used. Indicates that weighted prediction is applied to the Rice. When sps_weighted_pred_flag is equal to 0, The weighted prediction unit 3094 sets the value of pps_weighted_pred_flag to 0. If it does not exist, set the value to 0.

[0206] pps_weighted_bipred_flag equal to 0 means that weighted prediction is used for B slices that refer to PPS. Indicates that weighted prediction is not applied. pps_weighted_bipred_flag equal to 1 indicates that weighted prediction is applied to B slices that refer to the PPS. sps_weighted_bipred_flag equal to 0 indicates that weighted prediction is not applied to B slices that refer to the PPS. When the weighted prediction unit 3094 detects a weighted bipred flag, the weighted prediction unit 3094 sets the value of the flag to 0. If the flag does not exist, the weighted prediction unit 3094 sets the value to 0.

[0207] Fig. 20 shows the Weighted prediction parameters syntax() of Non-Patent Document 1, which is called in the slice header. Here, when luma_weight_l0_flag[i] is 1, it indicates that there is a weighting coefficient for the luminance component of L0 prediction. When luma_weight_l0_flag[i] is 0, it indicates that there is a weighting coefficient for the luminance component of L0 prediction. Indicates that a weighting factor for the chroma prediction value for L0 prediction is not present. If luma_weight_l0_flag[i] is not present, the weight predictor 3094 infers it to be equal to 0. If chroma_weight_l0_flag[i] is 1, indicates that a weighting factor for the chroma prediction value for L0 prediction is present. If chroma_weight_l0_flag[i] is 0, This flag indicates that a weighting factor for the chrominance predicted value of the L1 prediction is not present. If chroma_weight_l0_flag[i] is not present, the weight predictor 3094 infers it to be equal to 0. Similarly, if luma_weight_l1_flag[i] is 1, it indicates that a weighting factor for the luminance component of the L1 prediction is present. If luma_weight_l1_flag[i] is 0, it indicates that a weighting factor for the luminance component of the L1 prediction is not present. If luma_weight_l1_flag[i] is not present, the weight predictor 3094 infers it to be equal to 0. If chroma_weight_l1_flag[i] is 1, it indicates that a weighting factor for the chrominance predicted value of the L1 prediction is present. If chroma_weight_l1_flag[i] is 0, it indicates that a weighting factor for the chrominance predicted value of the L1 prediction is not present. If chroma_weight_l1_flag[i] is not present, the weight predictor 3094 infers it to be equal to 0.

[0208] In Non-Patent Document 1, the variable weightedPredFlag is derived as follows. If slice_type is equal to P, weightedPredFlag is set equal to pps_weighted_pred_flag defined in PPS. Otherwise, if slice_type is equal to B, weightedPredFlag is set equal to pps_weighted_bipred_flag defined in PPS.

[0209] However, the above setting has a problem in that it is not possible to fully express the relationship between the combination of the prediction methods (DMVR, BDOF, PROF, BCW) defined in Non-Patent Document 1 and weighted prediction.

[0210] Therefore, in this embodiment, the weighted prediction unit 3094 derives the variable weightedPredFlag as follows. ·If slice_type is equal to P, set weightedPredFlag to (pps_weighted_pred_flag &&((cIdx == 0)? luma_weight_l0_flag [refIdxL0]:chroma_weight_l0_flag[refIdxL0])). Otherwise (slice_type equals B), set weightedPredFlag to (pps_weighted_bipred_flag && ((cIdx == 0) ? (luma_weight_l0_flag[refIdxL0] || luma_weight_l1_flag[refIdxL1]) : (chroma_weight_l0_flag[refIdxL0] || chroma_weight_l1_flag[refIdxL1])). By deriving the weighting coefficients as described above, it becomes possible to specify separately for the luminance and color difference signals that weighted prediction is not performed when no weighting coefficient exists, thereby solving the above problem.

[0211] If one of the prediction list usage flags (predFlagL0 or predFlagL1) is 1 (uni-prediction) and weightedPredFlag is 0 (weighted prediction is not used), PredLX (LX is L0 or L1) is used. The following equation is processed to match the pixel bit depth.

[0212] pbSamples[x][y] = Clip3(0,(1<<bitDepth)-1,(PredLX[x][y]+offset1)> >shift1) Here, shift1=14-bitDepth, offset1=1<<(shift1-1).

[0213] In addition, both prediction list usage flags (predFlagL0 and predFlagL1) are 1 (bi-prediction PRED_BI ), and if weighted prediction is not used, the following equation is processed to average PredL0 and PredL1 and adjust the average to the number of pixel bits.

[0214] pbSamples[x][y] = Clip3(0,(1<<bitDepth)-1,(PredL0[x][y]+PredL1[x][y]+offset2)> >shift2) Here, shift2=15-bitDepth, offset2=1<<(shift2-1).

[0215] Furthermore, when uni-prediction and weighted prediction are performed, the weighted prediction unit 3094 derives a weighted prediction coefficient w0 and an offset o0 from the coded data, and performs processing according to the following equations.

[0216] pbSamples[x][y] = Clip3(0,(1< <bitDepth)-1, ((PredLX[x][y]*w0+(1<<(log2WD-1)))>>log2WD)+o0) Here, log2WD is a variable indicating a predetermined shift amount.

[0217] Furthermore, when bi-prediction PRED_BI and weighted prediction are performed, the weighted prediction unit 3094 derives weighted prediction coefficients w0, w1, o0, and o1 from the coded data and performs the processing of the following equations.

[0218] pbSamples[x][y] = Clip3(0,(1< <bitDepth)-1,(PredL0[x][y]*w0+PredL1[x][y]*w1+((o0+o1+1)<<log2WD))> >(log2WD+1)) In addition, in Non-Patent Document 1, the syntax of the Reference picture list structure syntax is In the semantics of abs_delta_poc_st[listIdx][rplsIdx][i], the value of the variable AbsDeltaPocSt[listIdx][rplsIdx][i] is changed depending on the values ​​of sps_weighted_pred_flag and sps_weighted_bipred_flag. However, because the Reference picture list structure syntax (ref_pic_list_struct) is called before sps_weighted_pred_flag and sps_weighted_bipred_flag are decoded in SPS, a problem occurs where decoding cannot be performed correctly.

[0219] As an embodiment to solve the above problem and enable correct decoding, ·Inside ref_pic_list_struct, prohibit the use of flags that turn tools on and off. ref_pic_list_struct is decoded using PPS and slice headers, not SPS. The ref_pic_list_struct is decoded after the flag that turns the SPS tool on and off is decoded. Using either of the above methods can solve the above problem.

[0220] (BCW forecast) Bi-prediction with CU-level Weights (BCW) prediction is a prediction method that allows switching of weighting factors determined in advance at the CU level. Two variables nCbW and nCbH that specify the width and height of the current coding block, two (nCbW) x (nCbH) arrays predSamplesL0 and predSamplesL1, flags predFlagL0 and predFlagL1 that indicate whether to use a prediction list, reference indices refIdxL0 and refIdxL1, and the index of BCW prediction. The BCW prediction process is performed using the index bcw_idx and the variable cIdx that specifies the index of the luminance and chrominance components, and the predicted sample values ​​of the (nCbW) x (nCbH) array pbSamples are output.

[0221] sps_bcw_enabled_flag, which indicates whether to use this prediction at the SPS level, is set to TRUE, and two reference indexes are used. If the reference pictures indicated by the indexes refIdxL0 and refIdxL1 do not have weighted prediction coefficients and the number of coding blocks is equal to or less than a certain number, the bcw_idx at the CU level is explicitly coded and decoded in the syntax, and the value is substituted for the variable bcwIdx. If bcw_idx does not exist, 0 is substituted for the variable bcwIdx.

[0222] If the variable bcwIdx is 0, the predicted sample values ​​are derived as follows:

[0223] pbSamples[x][y] = Clip3(0, (1 << bitDepth)- 1, (predSamplesL0[x][y] + predSamplesL1[x][y] + offset2)>> shift2) Otherwise, if bcwIdx is not equal to 0, the following applies:

[0224] The variable w1 is set equal to bcwWLut[bcwIdx]. bcwWLut[k] = {4, 5, 3, 10, -2}. do.

[0225] The variable w0 is set to (8-w1), and the predicted sample values ​​are derived as follows:

[0226] pbSamples[x][y] = Clip3(0, (1 << bitDepth)- 1, (w0 * predSamplesL0[x][y] + w1 * predSamplesL1[x][y] + offset3)>>(shift2 + 3)) When BCW prediction is used in the AMVP prediction mode, the inter prediction parameter decoding unit 303 decodes bcw_idx and sends it to the BCW unit 30955. When BCW prediction is used in the merge prediction mode, the inter prediction parameter decoding unit 303 decodes the merge index merge_idx, and the merge candidate derivation unit 30361 derives the bcwIdx of each merge candidate. The merge candidate derivation unit 30361 calculates the weighting coefficients of the neighboring blocks used to derive the merge candidates by In other words, in merge mode, the weighting factors used in the past are inherited as the weighting factors of the current block.

[0227] (Intra-predicted image generation unit 310) When predMode indicates an intra prediction mode, the intra predicted image generation unit 310 Intra prediction is performed using the intra prediction parameters input from the prediction parameter derivation unit 304 and reference pixels read from the reference picture memory 306 .

[0228] The inverse quantization and inverse transform unit 311 inverse quantizes the quantized transform coefficients input from the parameter decoding unit 302 to obtain transform coefficients.

[0229] The adder 312 adds, for each pixel, the predicted image of the block input from the predicted image generator 308 and the prediction error input from the inverse quantization and inverse transformer 311 to generate a decoded image of the block. The adder 312 stores the decoded image of the block in the reference picture memory 306 and also outputs it to the loop filter 305 .

[0230] (Configuration of a video encoding device) Next, the configuration of the video encoding device 11 according to this embodiment will be described. Fig. 15 is a block diagram showing the configuration of the video encoding device 11 according to this embodiment. The video encoding device 11 includes a prediction image generation unit 101, a subtraction unit 102, a transformation and quantization unit 103, an inverse quantization and inverse transformation unit 105, an addition unit 106, a loop filter 107, a prediction parameter memory (prediction parameter storage unit, frame memory) 108, a reference picture memory (reference image storage unit, frame memory) 109, a coding parameter determination unit 110, a parameter coding unit 111, a prediction parameter derivation unit 120, and an entropy coding unit 104.

[0231] The predicted image generation unit 101 generates a predicted image for each CU. The predicted image generation unit 101 includes the inter predicted image generation unit 309 and the intra predicted image generation unit 310, which have already been described, and therefore further description thereof will be omitted.

[0232] The subtraction unit 102 generates a prediction error by subtracting pixel values ​​of the predicted image of the block input from the predicted image generation unit 101 from pixel values ​​of the image T. The subtraction unit 102 outputs the prediction error to the transformation and quantization unit 103.

[0233] The transform / quantization unit 103 calculates transform coefficients by frequency transforming the prediction errors input from the subtraction unit 102, and derives quantized transform coefficients by quantizing the prediction errors. The quantized transform coefficients are output to the parameter coding unit 111 and the inverse quantization and inverse transform unit 105 .

[0234] The inverse quantization and inverse transform unit 105 is the same as the inverse quantization and inverse transform unit 311 (FIG. 7) in the video decoding device 31. The calculated prediction error is output to the adder 106.

[0235] The parameter coding unit 111 includes a header coding unit 1110, a CT information coding unit 1111, and a CU coding unit 1112 (prediction mode coding unit). The CU coding unit 1112 further includes a TU coding unit 1114. The outline of the operation of each module is explained below.

[0236] The header encoding unit 1110 performs encoding processing of parameters such as header information, division information, prediction information, and quantized transform coefficients.

[0237] The CT information encoding unit 1111 encodes QT, MT (BT, TT) division information and the like.

[0238] The CU encoding unit 1112 encodes CU information, prediction information, division information, and the like.

[0239] When a prediction error is included in a TU, the TU encoding unit 1114 encodes the QP update information and the quantized prediction error.

[0240] The CT information encoding unit 1111 and the CU encoding unit 1112 supply syntax elements such as inter prediction parameters (predMode, merge_flag, merge_idx, inter_pred_idc, refIdxLX, mvp_LX_idx, mvdLX), intra prediction parameters, and quantized transform coefficients to the parameter encoding unit 111.

[0241] The entropy coding unit 104 receives the quantized transform coefficients and coding parameters (division information, prediction parameters) from the parameter coding unit 111. These are then entropy coded to generate and output a coded stream Te.

[0242] The prediction parameter derivation unit 120 is a means including an inter-prediction parameter coding unit 112 and an intra-prediction parameter coding unit 113, and derives intra-prediction parameters and intra-prediction parameters from the parameters input from the coding parameter determination unit 110. The derived intra-prediction parameters and intra-prediction parameters are output to the parameter coding unit 111. can be.

[0243] (Configuration of Inter-Prediction Parameter Encoding Unit) As shown in FIG. 16, the inter prediction parameter coding unit 112 includes a parameter coding control unit 1121 and an inter prediction parameter derivation unit 303. The inter prediction parameter derivation unit 303 has the same configuration as the video decoding device. The parameter coding control unit 1121 controls the merge input. It includes an index derivation unit 11211 and a vector candidate index derivation unit 11212 .

[0244] The merge index derivation unit 11211 derives merge candidates and the like, and calculates inter prediction parameters The vector candidate index derivation unit 11212 derives predicted vector candidates and outputs them to the inter prediction parameter derivation unit 303 and the parameter coding unit 111.

[0245] (Configuration of the intra-prediction parameter encoding unit 113) The intra-prediction parameter coding unit 113 performs intra-prediction parameter coding with a parameter coding control unit 1131. The video decoding device includes a parameter derivation unit 304. The intra-prediction parameter derivation unit 304 has the same configuration as the video decoding device.

[0246] However, unlike the video decoding device, the inter prediction parameter derivation unit 303 and the intra prediction The input to the parameter derivation unit 304 is the encoding parameter determination unit 110 and the prediction parameter memory 108. and outputs it to parameter coding section 111.

[0247] The adder 106 calculates the pixel values ​​of the predicted block input from the predicted image generator 101 and the inverse quantized and inverse The adder 106 generates a decoded image by adding, for each pixel, the prediction errors input from the converter 105. The adder 106 stores the generated decoded image in the reference picture memory 109.

[0248] The loop filter 107 performs deblocking filtering, SAO, and ALF on the decoded image generated by the adder 106. Note that the loop filter 107 does not necessarily include the above three types of filters. For example, the filter may be configured with only a deblocking filter.

[0249] The prediction parameter memory 108 stores the prediction parameters generated by the coding parameter determination unit 110 in a predetermined location for each current picture and CU.

[0250] The reference picture memory 109 stores the decoded image generated by the loop filter 107 at a predetermined location for each current picture and CU.

[0251] The encoding parameter determination unit 110 determines one set of encoding parameters from among a plurality of sets of encoding parameters. The coding parameters are the above-mentioned QT, BT or TT division information, prediction parameters, or parameters to be coded that are generated in relation to these. The predicted image generation unit 101 generates a predicted image using these coding parameters.

[0252] The encoding parameter determination unit 110 determines the size of the information amount and the encoding parameter for each of the plurality of sets. The RD cost value indicating the error is calculated. The RD cost value is, for example, the sum of the code amount and the value obtained by multiplying the squared error by a coefficient λ. The code amount is the information amount of the coded stream Te obtained by entropy coding the quantization error and the coding parameters. The squared error is calculated in the subtraction unit 102. The coefficient λ is a preset real number greater than zero. The coding parameter determination unit 110 determines the set of coding parameters that minimizes the calculated cost value. The encoding parameter determination unit 110 selects the encoding parameter. The result is output to the encoding unit 111 and the prediction parameter derivation unit 120.

[0253] Note that, in the above-described embodiment, the video encoding device 11 and a part of the video decoding device 31, for example, the entropy decoding unit 301, the parameter decoding unit 302, the loop filter 305, the predicted image generation unit 306, The control unit 308, the inverse quantization and inverse transform 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 unit 103, the entropy coding unit 104, the inverse quantization and inverse transform unit 105, the loop filter 107, the coding parameter determination unit 110, the parameter coding unit 111, and the prediction parameter derivation unit 120 may be realized by a computer. The program for realizing the above may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read and executed by a computer system. Note that the "computer system" here refers to a computer system built into either the video encoding device 11 or the video decoding device 31, and includes hardware such as an OS and peripheral devices. Also, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a computer-readable medium. "A computer-readable recording medium" refers to a storage device, such as a hard disk, built into a computer system. Furthermore, "computer-readable recording medium" may also include a device that dynamically stores a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, or a device that stores a program for a fixed period of time, such as volatile memory within a computer system that serves as a server or client in such cases. Furthermore, the program may be one that realizes part of the aforementioned functions, or may be one that can realize the aforementioned functions in combination with a program already stored in the computer system.

[0254] Furthermore, part or all of the video encoding device 11 and video decoding device 31 in the above-described embodiments may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each functional block of the encoding device 11 and the video decoding device 31 may be implemented as a processor individually, or part or all of them may be integrated into a processor. The integrated circuit method is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, an integrated circuit based on that technology may also be used.

[0255] One embodiment of the present invention has been described in detail above with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes and the like are possible within the scope that does not deviate from the gist of the present invention.

[0256] [Application example] The above-described video encoding device 11 and video decoding device 31 can be mounted on various devices that transmit, receive, record, and play back video. The video may be a natural video captured by a camera or the like, or an artificial video (including CG and GUI) generated by a computer or the like.

[0257] First, it will be explained with reference to FIG. 2 that the above-described video encoding device 11 and video decoding device 31 can be used for transmitting and receiving video.

[0258] 2(a) is a block diagram showing the configuration of a transmitting device PROD_A equipped with a video encoding device 11. As shown in the figure, the transmitting device PROD_A includes an encoding unit PROD_A1 that encodes video to obtain encoded data, a modulation unit PROD_A2 that modulates a carrier wave with the encoded data obtained by the encoding unit PROD_A1 to obtain a modulated signal, and a transmitting unit PROD_A3 that transmits the modulated signal obtained by the modulation unit PROD_A2. The above-described video encoding device 11 is used as this encoding unit PROD_A1.

[0259] The transmitting device PROD_A captures moving images as a supply source of moving images to be input to the encoding unit PROD_A1. a recording medium PROD_A5 on which moving images are recorded; an input terminal PROD_A6 for inputting moving images from the outside; and an image processing unit A7 for generating or processing images. In the figure, the transmitting device PROD_A is shown as having all of these components, but some of them may be omitted.

[0260] The recording medium PROD_A5 may also be one that records unencoded moving images. Alternatively, the recording medium PROD_A5 may be a recording medium that has been coded using a coding method for recording that is different from the coding method for transmission. In the latter case, a decoding unit ( It is advisable to use a device (not shown) between the two.

[0261] 2(b) is a block diagram showing the configuration of a receiving device PROD_B equipped with a video decoding device 31. As shown in the figure, the receiving device PROD_B includes a receiving unit PROD_B1 that receives a modulated signal, and a demodulating unit PROD_B2 that obtains coded data by demodulating the modulated signal received by the receiving unit PROD_B1. and a decoding unit PROD_B3 that obtains a moving image by decoding the coded data obtained by the demodulation unit PROD_B2. The above-mentioned moving image decoding device 31 is used as this decoding unit PROD_B3. .

[0262] The receiving device PROD_B is a supply destination of the video output from the decoding unit PROD_B3, and displays the video. The device may further include a display PROD_B4 for recording moving images, a recording medium PROD_B5 for recording moving images, and an output terminal PROD_B6 for outputting moving images to the outside. Although the receiving device PROD_B is illustrated as having the above components, some of these may be omitted.

[0263] The recording medium PROD_B5 is for recording unencoded moving images. In the latter case, a signal from the decoder PROD_B3 to the recording medium PROD_B5 is inserted between the decoder PROD_B3 and the recording medium PROD_B5. It is preferable to interpose an encoding unit (not shown) that encodes the acquired moving images according to an encoding method for recording.

[0264] The transmission medium for transmitting the modulated signal may be wireless or wired. The transmission mode for transmitting the modulated signal may be broadcast (here, this refers to a transmission mode in which the destination is not specified in advance) or communication (here, this refers to a transmission mode in which the destination is specified in advance). In other words, the transmission of the modulated signal may be realized by any of wireless broadcasting, wired broadcasting, wireless communication, and wired communication.

[0265] For example, a broadcasting station (such as a broadcasting facility) / receiving station (such as a television receiver) for terrestrial digital broadcasting is an example of a transmitting device PROD_A / receiving device PROD_B that transmits and receives modulated signals via wireless broadcasting. Also, a broadcasting station (such as a broadcasting facility) / receiving station (such as a television receiver) for cable television broadcasting is an example of a transmitting device PROD_A / receiving device PROD_B that transmits and receives modulated signals via cable broadcasting.

[0266] Furthermore, a server (such as a workstation) / client (such as a television receiver, personal computer, or smartphone) of an Internet-based VOD (Video On Demand) service or video sharing service is an example of a transmitter PROD_A / receiver PROD_B that transmits and receives modulated signals via communication (usually, a LAN uses either a wireless or wired transmission medium, while a WAN uses a wired transmission medium). Here, personal computers include desktop PCs, laptop PCs, and tablet PCs. Smartphones also include multi-function mobile phone terminals.

[0267] The client of the video hosting service has the function of decoding the encoded data downloaded from the server and displaying it on a display, as well as the function of encoding the video images captured by a camera and uploading them to the server. In other words, the client of the video hosting service functions as both the transmitting device PROD_A and the receiving device PROD_B.

[0268] Next, it will be explained with reference to FIG. 3 that the above-described video encoding device 11 and video decoding device 31 can be used for recording and reproducing video.

[0269] Fig. 3(a) is a block diagram showing the configuration of a recording device PROD_C equipped with the above-mentioned video encoding device 11. As shown in the figure, the recording device PROD_C is equipped with an encoding unit PROD_C1 that obtains encoded data by encoding video, and a writing unit PROD_C2 that writes the encoded data obtained by the encoding unit PROD_C1 onto a recording medium PROD_M. The above-mentioned video encoding device 11 is It is used as the encoding unit PROD_C1.

[0270] The recording medium PROD_M may be (1) a type built into the recording device PROD_C, such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive), (2) a type connected to the recording device PROD_C, such as an SD memory card or a USB (Universal Serial Bus) flash memory, or (3) a DVD (Digital Versatile Disc: registered). (registered trademark) or BD (Blu-ray Disc: registered trademark), It may also be one that is loaded into a live device (not shown).

[0271] The recording device PROD_C also receives the video as a video source to be input to the encoding unit PROD_C1. The camera PROD_C3 captures an image, an input terminal PROD_C4 receives moving images from an external device, a receiving unit PROD_C5 receives moving images, and an image processing unit PROD_C6 generates or processes images. In the figure, the recording device PROD_C is shown as having all of these components, but some of them may be omitted.

[0272] The receiving unit PROD_C5 may receive unencoded video. Alternatively, the receiving unit PROD_C5 may receive coded data coded by a coding method for transmission that is different from the coding method for recording. In the latter case, it is preferable to interpose a decoding unit for transmission (not shown) between the receiving unit PROD_C5 and the coding unit PROD_C1, which decodes the coded data coded by the coding method for transmission.

[0273] Examples of such a recording device PROD_C include a DVD recorder, a BD recorder, and an HDD (Hard Disk Drive) recorder (in this case, the input terminal PROD_C4 or the receiving unit PROD_C5 is the main source of the moving image). Also, a camcorder (in this case, the camera PROD_C3 is the main source of the moving image), a personal computer (in this case, the receiving unit PROD_C5 or the image The processing unit C6 is the main source of video images), a smartphone (in this case, the camera PROD_C3 or the receiving unit PROD_C5 is the main source of the moving image), such a recording device PROD_C This is an example.

[0274] Fig. 3(b) is a block diagram showing the configuration of a playback device PROD_D equipped with the above-mentioned video decoding device 31. As shown in the figure, the playback device PROD_D includes a reading unit PROD_D1 that reads out coded data written on a recording medium PROD_M, and a decoding unit PROD_D2 that obtains video by decoding the coded data read by the reading unit PROD_D1. The above-mentioned video decoding device 31 is , this is used as the decoding unit PROD_D2.

[0275] The recording medium PROD_M may be (1) a type that is built into the playback device PROD_D, such as an HDD or SSD, or (2) a type that is not built into the playback device PROD_D, such as an SD memory card or a USB flash memory. (3) DVD, BD, etc. As shown in the figure, the disc may be loaded into a drive device (not shown) built into the playback device PROD_D.

[0276] Furthermore, the playback device PROD_D receives the video output from the decoding unit PROD_D2 and sends the video to The image processing device may further include a display PROD_D3 for displaying the moving image, an output terminal PROD_D4 for outputting the moving image to the outside, and a transmission unit PROD_D5 for transmitting the moving image. Although the configuration of the playback device PROD_D is illustrated, some of the components may be omitted.

[0277] The transmission unit PROD_D5 may transmit unencoded video. Alternatively, the decoder PROD_D2 may transmit coded data coded by a coding method for transmission that is different from the coding method for recording. In the latter case, it is preferable to interpose a coding unit (not shown) between the decoder PROD_D2 and the transmitter PROD_D5, which codes the video by the coding method for transmission.

[0278] Examples of such a playback device PROD_D include a DVD player, a BD player, and an HDD player (in this case, the output terminal PROD_D4 to which a television receiver or the like is connected operates). In addition, television receivers (in this case, the display PROD_D3 is the main supply destination of moving images), digital signage (also called electronic billboards or electronic bulletin boards, etc.) a display PROD_D3 or a transmitter PROD_D5 is the main supply destination of the moving image), a desktop PC (in this case, the output terminal PROD_D4 or a transmitter PROD_D5 is the main supply destination of the moving image), a laptop or tablet PC (in this case, the display PROD_D3 or a transmitter PROD_D5 is the main supply destination of the moving image). Examples of such a playback device PROD_D include a playback device PROD_D1 (in which case the display PROD_D3 or the transmission unit PROD_D5 is the main supply destination of the video images) and a smartphone (in which case the display PROD_D3 or the transmission unit PROD_D5 is the main supply destination of the video images).

[0279] (hardware and software implementations) Furthermore, each block of the video decoding device 31 and the video encoding device 11 may be realized in hardware by a logic circuit formed on an integrated circuit (IC chip), or may be realized by a CPU. This may be realized in software using a Central Processing Unit (Central Processing Unit).

[0280] In the latter case, each of the above devices includes a CPU that executes instructions from a program to realize each function, ROM (Read Only Memory) stores the program, and RAM (Random Access Memory) expands the program. The device may include a storage device (recording medium) such as an access memory (access memory) for storing the above programs and various data. The object of the embodiment of the present invention can also be achieved by supplying each of the devices with a recording medium on which program code (executable program, intermediate code program, source program) of the control program for each of the devices, which is software for realizing the above functions, is recorded in a computer-readable manner, and having the computer (or CPU or MPU) read and execute the program code recorded on the recording medium.

[0281] Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy disks (registered trademark) and hard disks, and CD-ROMs (Compact Disc Read-Only Memory), MO disks (Magneto-Optical discs), MDs (Mini Discs), DVDs (Digital Versatile Discs: registered trademark), CD-Rs (CD Recordable), and Blu-ray discs. Discs, including optical discs such as (Disc: registered trademark), IC cards (including memory cards) / Optical cards and other cards, mask ROM / EPROM (Erasable Programmable Read-Only Memory) / EEPROM (Electrically Erasable and Programmable Read-Only Memory: registered trademark) Semiconductor memories such as flash ROMs, or logic circuits such as PLDs (Programmable logic devices) and FPGAs (Field Programmable Gate Arrays) can be used.

[0282] Furthermore, each of the above devices may be configured to be connectable to a communications network, and the program code may be supplied via the communications network. This communications network may be any network capable of transmitting the program code. For example, the Internet, an intranet, an extranet, a local area network (LAN), an integrated services digital network (ISDN), a value-added network (VAN), a community antenna television / cable television (CATV) communications network, a virtual private network, a telephone line network, a mobile communications network, a satellite communications network, etc. Furthermore, the transmission media constituting this communications network may be any medium capable of transmitting the program code, and are not limited to any particular configuration or type. For example, the present invention can be used in wired communication such as IEEE (Institute of Electrical and Electronic Engineers) 1394, USB, power line carrier, cable TV line, telephone line, or ADSL (Asymmetric Digital Subscriber Line) line, or in wireless communication such as IrDA (Infrared Data Association), infrared such as that used in remote controls, Bluetooth (registered trademark), IEEE 802.11 wireless, HDR (High Data Rate), NFC (Near Field Communication), DLNA (Digital Living Network Alliance: registered trademark), mobile phone networks, satellite lines, or terrestrial digital broadcasting networks. Note that the present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

[0283] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. In other words, embodiments obtained by combining technical means modified appropriately within the scope of the claims are also included in the technical scope of the present invention. [Industrial Applicability]

[0284] The embodiments of the present invention can be suitably applied to a video decoding device that decodes coded data in which image data has been coded, and a video coding device that generates coded data in which image data has been coded. Therefore, it can be suitably applied to the data structure of the referenced coded data. [Explanation of symbols]

[0285] 31 Image decoding device 301 Entropy Decoding Unit 302 Parameter Decoding Unit 303 Inter-prediction parameter derivation unit 304 Intra prediction parameter derivation unit 305, 107 Loop filter 306, 109 Reference Picture Memory 307, 108 Prediction parameter memory 308, 101 Prediction image generation unit 309 Inter-prediction image generation unit 310 Intra-prediction image generation unit 311, 105 Inverse quantization and inverse transform unit 312, 106 Addition section 320 Prediction parameter derivation part 11 Image encoding device 102 Subtraction section 103 Transformation and Quantization Unit 104 Entropy coding unit 110 Encoding parameter determination unit 111 Parameter Encoding Unit 112 Inter-prediction parameter coding unit 113 Intra prediction parameter coding unit 120 Prediction parameter derivation part

Claims

1. an affine prediction unit that derives affine prediction parameters from motion vectors of a plurality of control points; a PROF (Prediction Refinement with Optical Flow) unit that receives a motion vector difference array derived from the affine prediction parameters and a predicted image array derived from the affine prediction parameters and derives predicted sample values ​​from the motion vector difference array and the predicted image array, 10. A video decoding device, comprising: a motion vector difference array clipped to a range using a fixed value that is independent of pixel bit length; and a motion vector difference array clipped to a range using a fixed value that is independent of pixel bit length;

2. an affine prediction unit that derives affine prediction parameters from motion vectors of a plurality of control points; a PROF (Prediction Refinement with Optical Flow) unit that receives a motion vector difference array derived from the affine prediction parameters and a predicted image array derived from the affine prediction parameters and derives predicted sample values ​​from the motion vector difference array and the predicted image array, 10. A video encoding device, comprising: a motion vector differential array clipped to a range using a fixed value that is independent of pixel bit length; and a motion vector differential array clipped to a range using a fixed value that is equal to 32.

Images