JP2021013110A - Image decoding device and image encoding device - Google Patents

Abstract

To solve a problem that in the case of use of joint color difference residual coding, when mapping of quantization parameters of brightness and color difference are changed, three tables of first color difference, second color difference, and joint color difference residual coding are transmitted, which causes increase in table size.SOLUTION: An image decoding device includes a quantization parameter driving unit for referring to a color difference quantization table and deriving a quantization parameter of a color difference from an intermediate quantization parameter derived from a quantization parameter of brightness in a joint color difference residual coding mode in which a predicted residual of a first color component is decoded to derive a predicted residual of a second color component, and derives a color difference quantization table mode, and sets the quantization table of a first color difference or second color difference in the color difference quantization table of the joint color difference residual coding mode according to the color difference quantization table mode.SELECTED DRAWING: Figure 16

Description

Embodiments of the present invention relate to a moving image decoding device and a moving image coding device.

In order to efficiently transmit or record a moving image, a moving image coding device that generates encoded data by encoding the moving image, and a moving image that generates a decoded image by decoding the encoded data. An image decoding device is used.

Specific examples of the moving image coding method include methods proposed by H.264 / AVC and HEVC (High-Efficiency Video Coding).

In such a moving image coding method, the image (picture) constituting the moving image is a slice obtained by dividing the image and a coding tree unit (CTU) obtained by dividing the slice. ), A coding unit obtained by dividing the coding tree unit (sometimes called a coding unit (CU)), and a conversion unit (TU:) obtained by dividing the coding unit. It is managed by a hierarchical structure consisting of (Transform Unit), and is encoded / decoded for each CU.

Further, in such a moving image coding method, a predicted image is usually generated based on a locally decoded image obtained by encoding / decoding an input image, and the predicted image is obtained from the input image (original image). The prediction error obtained by subtraction (sometimes referred to as "difference image" or "residual image") is encoded. Examples of the method for generating a prediction image include inter-screen prediction (inter-screen prediction) and in-screen prediction (intra-prediction).

In addition, Non-Patent Document 1 is mentioned as a recent moving image coding and decoding technique. Non-Patent Document 1 discloses a joint color difference residual coding technique for deriving the residual of one color difference from the residual of the other color difference. Non-Patent Document 2 knows a technique for transmitting a table for deriving a color difference quantization parameter QPC from a brightness quantization parameter QPY.

"Versatile Video Coding (Draft 5)", JVET-N1001-v10, Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29/WG 11 "AHG15: Flexible luma-to-chroma quantization parameter tables", JVET-O0562-v1, Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29/WG 11, 2019- 06-26 "CE7: Joint coding of chrominance residuals (CE7-1)", JVET-N0054-v1, Joint Video Exploration Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29/WG 11, 2019 -03-12

In Non-Patent Document 2, the relationship (mapping) between the brightness quantization parameter and the color difference quantization parameter can be changed. However, when joint color difference residual coding is used as in Non-Patent Document 1, the relationship (mapping) is changed. Since the three tables of the first color difference, the second color difference, and the joint color difference residual coding are transmitted, there is a problem that the table size becomes large.

In order to solve the above problems, the image decoding device according to one aspect of the present invention is an image decoding device provided with a decoding unit that decodes the predicted residual, and the decoding unit is a first color component. It has a joint color difference residual coding mode that decodes the predicted residuals to derive the predicted residuals for the second color component, and refers to the color difference quantization table for intermediate quantization derived from the luminance quantization parameters. A quantization parameter derivation unit for deriving color difference quantization parameters from parameters is provided, and the above-mentioned quantization parameter derivation unit derives a color difference quantization table mode, and a joint color difference residual according to the color difference quantization table mode. It is characterized in that a first color difference quantization table or a second color difference quantization table is set in the color difference quantization table of the coding mode.

In the image decoding apparatus according to one aspect of the present invention, the quantization parameter derivation unit uses the color difference quantization table used in the joint color difference residual coding mode according to the color difference quantization table mode as the color difference quantum of the first color difference. It is characterized in that it is derived using a conversion table and a color difference quantization table of a second color difference.

The image decoding device according to one aspect of the present invention is an image decoding device provided with a decoding unit that decodes the predicted residual, and the decoding unit decodes the predicted residual of the first color component to obtain a first. It has a joint color difference residual coding mode that derives the predicted residuals for the color components of 2, and refers to the color difference quantization table to obtain the color difference quantization parameters from the intermediate quantization parameters derived from the brightness quantization parameters. It is provided with a quantization parameter derivation unit to be derived, and the above-mentioned quantization parameter derivation unit derives a color difference quantization table mode and uses it as a color difference quantization parameter of the joint color difference residual coding mode according to the color difference quantization table mode. , The case where the quantization parameter of the first color difference or the quantization parameter of the second color difference is set is provided.

In the image decoding apparatus according to one aspect of the present invention, the quantization parameter derivation unit uses the quantization parameter used in the joint color difference residual coding mode as the first color difference quantization parameter according to the color difference quantization table mode. It is characterized by providing a case of deriving using the quantization parameter of the second color difference.

According to the above configuration, any of the above problems can be solved.

It is the schematic which shows the structure of the image transmission system which concerns on this embodiment. It is a figure which showed the structure of the transmission device which carried out the moving image coding device which concerns on this embodiment, and the receiving device which carried out moving image decoding device. PROD_A indicates a transmitting device equipped with a moving image encoding device, and PROD_B indicates a receiving device equipped with a moving image decoding device. It is a figure which showed the structure of the recording apparatus which carried out the moving image coding apparatus which concerns on this embodiment, and the reproduction apparatus which mounted on moving image decoding apparatus. PROD_C indicates a recording device equipped with a moving image encoding device, and PROD_D indicates a playback device equipped with a moving image decoding device. It is a figure which shows the hierarchical structure of the data of a coded stream. It is a figure which shows the division example of CTU. It is the schematic which shows the structure of the moving image decoding apparatus which concerns on this embodiment. It is a flowchart explaining the schematic operation of the moving image decoding apparatus which concerns on this embodiment. It is a figure which shows an example of the syntax table about a plurality of sign flags which concerns on this embodiment. It is a figure which shows an example of the syntax table about a plurality of sign flags which concerns on this embodiment. It is a figure which shows the syntax table of transform_unit () which concerns on this embodiment. It is a figure which shows the relationship between the value of tu_cbf_cb [x0] [y0] and tu_cbf_cr [x0] [y0] which concerns on this embodiment, and a joint chroma coding mode. It is a block diagram which shows the structure of the moving image coding apparatus which concerns on this embodiment. It is a block diagram which shows the structure of the inverse quantization unit and the inverse conversion unit which concerns on this embodiment. This is an example of the syntax configuration of the quantization table information of this embodiment. This is an example of the syntax configuration of the quantization table information of this embodiment. It is a figure which shows the derivation method of the quantization table used for the joint color difference residual coding of this embodiment. It is a figure which shows the derivation method of the quantization table used for the joint color difference residual coding of this embodiment. This is an example of the default quantization table of this embodiment.

(First Embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing a configuration of an image transmission system 1 according to the present embodiment.

The image transmission system 1 is a system that transmits a coded stream in which a coded image is encoded, decodes the transmitted coded stream, and displays an image. The image transmission system 1 includes a moving image coding device (image coding device) 11, a network 21, a moving image decoding device (image decoding device) 31, and a moving image display device (image display device) 41. ..

The image T is input to the moving image coding device 11.

The network 21 transmits the coded stream Te generated by the moving image coding device 11 to the moving image decoding device 31. The network 21 is an Internet (Internet), a wide area network (WAN: Wide Area Network), a small network (LAN: Local Area Network), or a combination thereof. 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 and satellite broadcasting. Further, the network 21 may be replaced with a storage medium such as a DVD (Digital Versatile Disc: registered trademark) or BD (Blue-ray Disc: registered trademark) on which a coded stream Te is recorded.

The moving image decoding device 31 decodes each of the coded streams Te transmitted by the network 21 and generates one or a plurality of decoded images Td.

The moving image display device 41 displays all or a part of one or a plurality of 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 display form include stationary, mobile, and HMD. Further, when the moving image decoding device 31 has a high processing capacity, an image having a high image quality is displayed, and when the moving image decoding device 31 has a lower processing capacity, an image which does not require a high processing capacity and a display capacity is displayed. ..

<Operator>
The operators used herein are described below.

>> is right bit shift, << is left bit shift, & is bitwise AND, | is bitwise OR
, | = Is the OR assignment operator, and || indicates the OR.

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

Clip3 (a, b, c) is a function that clips c to a value greater than or equal to a and less than or equal to b, returning a if c <a, returning b if c> b, and other cases. Is a function that returns c (where a <= b).

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

Int (a) is a function that returns an integer value of a.

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

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

a / d represents the division of a by d (rounded down to the nearest whole number).

<Structure of coded stream Te>
Prior to the detailed description of the moving image coding device 11 and the moving image decoding device 31 according to the present embodiment, the data of the coded stream Te generated by the moving image coding device 11 and decoded by the moving image decoding device 31. The structure will be described.

FIG. 4 is a diagram showing a hierarchical structure of data in the coded stream Te. The coded stream Te typically includes a sequence and a plurality of pictures that make up the sequence. In FIG. 4, the coded video sequence that defines the sequence SEQ, the coded picture that defines the picture PICT, the coded slice that defines the slice S, the coded slice data that defines the slice data, and the coded slice data, respectively. A diagram showing a coded tree unit included and a coded unit included in the coded tree unit is shown.

(Encoded video sequence)
The coded video sequence defines a set of data that the moving image decoding device 31 refers to in order to decode the sequence SEQ to be processed. The sequence SEQ includes a video parameter set (Video Parameter Set), a sequence parameter set SPS (Sequence Parameter Set), a picture parameter set PPS (Picture Parameter Set), a picture PICT, and a picture PICT, as shown in the encoded video sequence of FIG. Includes Supplemental Enhancement Information (SEI).

The video parameter set VPS is a set of coding parameters common to a plurality of moving images in a moving image composed of a plurality of layers, and a set of coding parameters related to the plurality of layers included in the moving image and individual layers. The set is defined.

The sequence parameter set SPS defines a set of coding parameters that the moving image decoding device 31 refers to in order to decode the target sequence. For example, the width and height of the picture are specified. There may be a plurality of SPSs. In that case, select one of multiple SPSs from PPS.

The picture parameter set PPS defines a set of coding parameters that the moving image decoding device 31 refers to in order to decode each picture in the target sequence. For example, a reference value of the quantization width used for decoding a picture (pic_init_qp_minus26) and a flag indicating the application of weighted prediction (weighted_pred_flag) are included. There may be a plurality of PPSs. In that case, one of a plurality of PPSs is selected from each picture in the target sequence.

(Encoded picture)
The coded picture defines a set of data referred to by the moving image decoding device 31 in order to decode the picture PICT to be processed. The picture PICT includes slices 0 to NS-1 as shown in the coded picture in FIG. 4 (NS is the total number of slices contained in the picture PICT).
..

In the following, when it is not necessary to distinguish between slice 0 and slice NS-1, the subscripts of the symbols may be omitted. The same applies to the data included in the coded stream Te described below and with subscripts.

(Coded slice)
The coded slice defines a set of data referred to by the moving image decoding device 31 in order to decode the slice S to be processed. The slices are as shown in the coded slice of FIG.
Contains slice header and slice data.

The slice header contains a group of coding parameters referred to by the moving image decoding device 31 to determine the decoding method of the target slice. The slice type specification information (slice_type) that specifies the slice type is an example of the coding parameters included in the slice header.

Slice types that can be specified by the slice type specification information include (1) I slices that use only intra-prediction during coding, and (2) P-slices that use unidirectional prediction or intra-prediction during coding. (3) Examples include a B slice that uses unidirectional prediction, bidirectional prediction, or intra prediction at the time of coding. Note that the inter-prediction is not limited to single prediction and bi-prediction, and a prediction image may be generated using more reference pictures. Below, P
, B slices refer to slices containing blocks for which inter-prediction can be used.

The slice header may include a reference (pic_parameter_set_id) to the picture parameter set PPS.

(Coded slice data)
The coded slice data defines a set of data referred to by the moving image decoding device 31 in order to decode the slice data to be processed. The slice data contains a CTU, as shown in the coded slice header of FIG. A CTU is a fixed-size (for example, 64x64) block that constitutes a slice, and is sometimes called a maximum coding unit (LCU: Largest Coding Unit).

(Encoded tree unit)
The coded tree unit of FIG. 4 defines a set of data referred to by the moving image decoding device 31 in order to decode the CTU to be processed. CTU is recursive quadtree division (QT (Quad Tree) division), binary tree division (BT (Binary Tree) division) or ternary tree division (TT (Ternary Tree) division).
) Divide) into the coding unit CU, which is the basic unit of coding processing. The combination of BT division and TT division is called multi-tree division (MT (Multi Tree) division). A tree-structured node obtained by recursive quadtree division is called a coding node. 4
The intermediate nodes of the branch tree, the binary tree, and the ternary tree are coding nodes, and the CTU itself is also defined as the highest-level coding node.

CT is a QT division flag (cu_split_flag) indicating whether or not to perform QT division, MT as CT information.
It includes an MT division flag (split_mt_flag) indicating the presence or absence of division, an MT division direction (split_mt_dir) indicating the division direction of MT division, and an MT division type (split_mt_type) indicating the division type of MT division. cu_split_flag, split_mt_flag, split_mt_dir, split_mt_type are transmitted for each encoding node.

When cu_split_flag is 1, the coding node is divided into 4 coding nodes (QT in FIG. 5).

When cu_split_flag is 0 and split_mt_flag is 0, the coded node is not divided and has one CU as a node (no division in FIG. 5). The CU is the terminal node of the encoding node and is not divided any further. CU is a basic unit of coding processing.

When split_mt_flag is 1, the encoding node is MT split as follows. When split_mt_type is 0, the coded node is horizontally divided into two coded nodes when split_mt_dir is 1 (BT (horizontal split) in Fig. 5), and when split_mt_dir is 0, the coded node is coded in two. It is vertically divided into nodes (BT (vertical division) in Fig. 5). Also, when split_mt_type is 1, and when split_mt_dir is 1, the coded node is horizontally divided into 3 coded nodes (TT (horizontal division) in FIG. 5).
, When split_mt_dir is 0, the coded node is vertically divided into 3 coded nodes (Fig. 5).
TT (vertical division)). These are shown in the CT information in FIG.

If the CTU size is 64x64 pixels, the CU size is 64x64 pixels, 64x32 pixels, 32x64 pixels, 32x32 pixels, 64x16 pixels, 16x64 pixels, 32x16 pixels, 16x32 pixels, 16x16 pixels, 64x8 pixels, 8x64 pixels. , 32x8 pixels, 8x32 pixels, 16x8 pixels, 8x16 pixels, 8x8 pixels, 64x4 pixels, 4x64 pixels, 32x4 pixels, 4x32 pixels, 16x4 pixels, 4x16 pixels, 8x4 pixels, 4x8 pixels, and 4x4 pixels. ..

(Encoding unit)
As shown in the coding unit of FIG. 4, a set of data referred to by the moving image decoding device 31 in order to decode the coding unit to be processed is defined. Specifically, the CU is composed of a CU header CUH, a prediction parameter, a conversion parameter, a quantization conversion coefficient, and the like. The CU header defines the prediction mode and so on.

The prediction process may be performed in CU units or in sub-CU units that are further divided CUs. If the size of the CU and the sub CU are equal, there is only one sub CU in the CU. If the CU is larger than the size of the sub CU, the CU is split into sub CUs. For example, when the CU is 8x8 and the sub CU is 4x4, the CU is divided into four sub CUs consisting of two horizontal divisions and two vertical divisions.

There are two types of prediction (prediction mode): intra prediction and inter prediction. Intra prediction refers to prediction within the same picture, and inter prediction refers to prediction processing performed between different pictures (for example, between display times and between layer images).

The conversion / quantization process is performed in CU units, but the quantization conversion coefficient may be entropy-encoded in subblock units such as 4x4.

(Prediction parameter)
The prediction image is derived by the prediction parameters associated with the block. Prediction parameters include intra-prediction and inter-prediction prediction parameters.

(Configuration of moving image decoding device)
The configuration of the moving image decoding device 31 (FIG. 6) according to the present embodiment will be described.

The moving image decoding device 31 includes an entropy decoding unit 301, a parameter decoding unit (predicted image decoding device) 302, a loop filter 305, a reference picture memory 306, a predicted parameter memory 307, a predicted image generator (predicted image generator) 308, and a reverse. It is composed of a quantization / inverse conversion unit 311 and an addition unit 312. In addition, in accordance with the moving image coding device 11 described later, there is also a configuration in which the moving image decoding device 31 does not include the loop filter 305.

The parameter decoding unit 302 further includes a header decoding unit 3020, a CT information decoding unit 3021, and a CU decoding unit 3022 (prediction mode decoding unit), and the CU decoding unit 3022 further includes a TU decoding unit 3024. These may be generically called a decoding module. The header decoding unit 3020 decodes the parameter set information such as VPS, SPS, and PPS, and the slice header (slice information) from the encoded data. The CT information decoding unit 3021 decodes the CT from the encoded data. The CU decoding unit 3022 decodes the CU from the encoded data. The TU decoding unit 3024 decodes the QP update information (quantization correction value) and the quantization prediction error (residual_coding) from the coded data when the TU contains a prediction error. Details of the TU decoding unit 3024 will be described later. In addition, the quantization prediction error may be called a transform coefficient.

Further, the parameter decoding unit 302 includes an inter-prediction parameter decoding unit 303 and an intra-prediction parameter decoding unit 304 (not shown). The prediction image generation unit 308 includes an inter prediction image generation unit 309 and an intra prediction image generation unit 310.

The stIdx decoding unit 131 of the TU decoding unit 3024 decodes the value stIdx indicating whether or not the inverse secondary conversion is used and the conversion basis from the encoded data, and outputs the value to the inverse secondary conversion unit 31121. The mts_idx decoding unit 132 of the TU decoding unit 3024 decodes the value mts_idx indicating the conversion matrix of the inverse core conversion (MTS) from the encoded data and outputs it to the inverse core conversion unit 31123. When stIdx is 0, the secondary transformation is not applied, when stIdx is 1, the transformation of one of the set (pair) of the secondary transformation matrix is shown, and when stIdx is 2, the above pair The transformation of the other is shown.

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

The entropy decoding unit 301 performs entropy decoding on the coded stream Te input from the outside, separates and decodes each code (syntax element). For entropy coding, a method of variable-length coding of syntax elements using a context (probability model) adaptively selected according to the type of syntax element and the surrounding situation, a predetermined table, or There is a method of variable-length coding the syntax element using a calculation formula. The former CABAC (Context Adaptive Binary Arithmetic Coding) stores a stochastic model updated for each encoded or decoded picture (slice) in memory. And P picture,
Alternatively, as the initial state of the B picture context, a picture probability model using the same slice type and the same slice level quantization parameter is set from the probability models stored in the memory. This initial state is used for encoding and decoding processing. The separated codes include prediction information for generating a prediction image, prediction error for generating a difference image, and the like.

The entropy decoding unit 301 outputs the separated codes to the parameter decoding unit 302. The separated codes are, for example, prediction mode predMode, merge flag merge_flag, merge index merge_idx, inter prediction identifier inter_pred_idc, reference picture index refIdxLX,
Prediction vector index mvp_LX_idx, difference vector mvdLX, etc. The control of which code is decoded is performed based on the instruction of the parameter decoding unit 302.

(Basic flow)
FIG. 7 is a flowchart illustrating a schematic operation of the moving image decoding device 31.

(S1100: Parameter set information decoding) The header decoding unit 3020 decodes the parameter set information such as VPS, SPS, and PPS from the encoded data.

(S1200: Decoding of slice information) The header decoding unit 3020 decodes the slice header (slice information) from the encoded data.

Hereinafter, the moving image decoding device 31 will perform S1300 to S5000 for each CTU included in the target picture.
The decoded image of each CTU is derived by repeating the process of.

(S1300: CTU information decoding) The CT information decoding unit 3021 decodes the CTU from the encoded data.

(S1400: CT information decoding) The CT information decoding unit 3021 decodes the CT from the encoded data.

(S1500: CU decoding) The CU decoding unit 3022 executes S1510 and S1520 to decode the CU from the encoded data.

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

(S1520: TU information decoding) When the TU contains a prediction error, the TU decoding unit 3024 decodes the QP update information (quantization correction value) and the quantization prediction error (residual_coding) from the encoded data. The QP update information is a difference value from the quantization parameter prediction value qPpred, which is the prediction value of the quantization parameter QP.

(S2000: Prediction image generation) The prediction image generation unit 308 generates a prediction image based on the prediction information for each block included in the target CU.

(S3000: Inverse quantization / inverse conversion) Inverse quantization / inverse conversion unit 311 executes inverse quantization / inverse conversion processing for each TU included in the target CU.

(S4000: Decoded image generation) The addition unit 312 decodes the target CU by adding the prediction image supplied by the prediction image generation unit 308 and the prediction error supplied by the inverse quantization / inverse conversion unit 311. Generate an image.

(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.

The loop filter 305 is a filter provided in the coding loop, which removes block distortion and ringing distortion to improve image quality. The loop filter 305 applies filters such as a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to the decoded image of the CU generated by the addition unit 312.

The reference picture memory 306 stores the decoded image of the CU generated by the addition unit 312 at a predetermined position for each target picture and the target CU.

The prediction parameter memory 307 stores the prediction parameters at a predetermined position for each CTU or CU to be decoded. Specifically, the prediction parameter memory 307 stores the parameters decoded by the parameter decoding unit 302 and the pred mode and the like separated by the entropy decoding unit 301.

PredMode, prediction parameters, etc. are input to the prediction image generation unit 308. Further, the prediction image generation unit 308 reads the reference picture from the reference picture memory 306. Prediction image generator 308
Generates a predicted image of a block or subblock using the predicted parameters and the read reference picture (reference picture block) in predMode. Here, the reference picture block is a set of pixels on the reference picture (usually called a block because it is rectangular), and is an area to be referred to for generating a predicted image.

The inverse quantization / inverse conversion unit 311 inversely quantizes the quantization conversion coefficient input from the entropy decoding unit 301 to obtain the conversion coefficient. This quantization transform coefficient is a coefficient obtained by performing frequency conversion such as DCT (Discrete Cosine Transform) or DST (Discrete Sine Transform) on the prediction error in the coding process. Is. The inverse quantization / inverse conversion unit 311 performs inverse frequency conversion such as inverse DCT and inverse DST on the obtained conversion coefficient, and calculates a prediction error. The inverse quantization / inverse conversion unit 311 outputs the prediction error to the addition unit 312.

The addition unit 312 adds the prediction image of the block input from the prediction image generation unit 308 and the prediction error input from the inverse quantization / inverse conversion unit 311 for each pixel to generate a decoded image of the block.
The addition unit 312 stores the decoded image of the block in the reference picture memory 306, and outputs the decoded image to the loop filter 305.

(Quantization parameter derivation unit)
The quantization parameter derivation unit 3026 decodes the quantization table information from the coded data and derives the quantization table ChromaQPTable [] []. For example, the quantization table information may be derived using piecewise linear approximation. Here, piecewise linear approximation is a method of defining end points called Pivot points and determining the value at the midpoint by connecting the end points linearly. Further, the slope of the section from 0 to the initial section and from the final section to the maximum value may be fixed at 1. Also, joint_cbcr_qp_table_idx described later
May be used to derive the quantization parameters for joint color difference residual coding.

(Decoding example 1 of quantization table)
FIG. 14 is an example of the syntax configuration of the quantization table information of the present embodiment, and includes joint_cbcr_qp_table_idx. The num_points_in_qp_table [i] of the syntax element is the number of Pivot points in the i-th color difference quantization table, and delta_qp_in_val [i] [j] is the horizontal distance of the j-th Pivot point in the i-th color difference quantization table. (Difference value from the j-1st horizontal coordinate for deriving the horizontal coordinate), delta_qp_out_val [i] [j] is the vertical distance of the Pivot point (the jth of the i-th color difference quantization table). The difference value from the j-1st vertical coordinate for deriving the vertical coordinate).

(S100) Initialize qpVal [i] [0] and cQPTable [i] [0]. QpBdOffsetC is the offset value that defines the range of color difference quantization parameters, qpVal [i] [] is the horizontal coordinates (input value) of the Pivot point, and cQPTable [i] [] is the vertical coordinates (output value) of the Pivot point. ..

qpVal [i] [0] = -QpBdOffsetC + delta_qp_in_val [i] [0]
cQPTable [i] [0] = -QpBdOffsetC + delta_qp_out_val [i] [0]
(S102) Pivot Point coordinates qpVal [i] [j] and cQPTable [i] [j] are derived.

for (j = 1; j <num_points_in_qp_table [i]; j ++) {
qpVal [i] [j] = qpVal [i] [j-1] + delta_qp_in_val [i] [j]
cQPTable [i] [j] = cQPTable [i] [j-1] + delta_qp_out_val [i] [j]
}
(S110) Derivation of the quantization table ChromaQpTable [i] [k] for the initial interval (from 0 to the first Pivot point). The following is an example of deriving a quantization table with the slope fixed at 1.

ChromaQpTable [i] [qpVal [i] [0]] = cQPTable [i] [0]
if (qpVal [i] [0] <-QpBdOffsetC) {
for (k = qpVal [i] [0] ―― 1; k> = -QpBdOffsetC; k-)
ChromaQpTable [i] [k] = Clip3 (-QpBdOffsetC, 69, ChromaQpTable [i] [k + 1] -1)
}
(S120) Derivation of the quantization table between the first Pivot point and the last Pivot point. This interval is a linear interval, and the quantization table is derived using the slope indicated by (delta_qp_out_val [j + 1] * m + sh) / delta_qp_in_val [j + 1].

for (j = 0; j <num_points_in_qp_table [i] -1; j ++) {
for (k = cQpTable [j] + 1, m = 1; k <= cQPTable [j + 1]; k ++, m ++)
sh = delta_qp_in_val [j + 1] >> 1
ChromaQpTable [i] [k] = ChromaQpTable [i] [cQpTable [j]] +
(delta_qp_out_val [j + 1] * m + sh) / delta_qp_in_val [j + 1]
(S130) Derivation of the quantization table for the final interval (from the last Pivot point to the end point). The following is an example of deriving with the slope fixed at 1.

if (qpVal [i] [num_points_in_qp_table [i] -1]! = 69)
for (k = qpVal [i] [num_points_in_qp_table [i] ―― 1] + 1; k <= 69; k ++)
ChromaQpTable [i] [k] = Clip3 (-QpBdOffsetC, 69, ChromaQpTable [i] [k-1] + 1)
(Decoding example 2 of the quantization table)
FIG. 15 is an example of the syntax configuration of the quantization table information of the present embodiment, and includes joint_cbcr_qp_table_idx. The example of FIG. 15 is characterized in that the slope of the linear section is limited to 1 or 0.

The syntax element qpc_start_idx [i] is the position of the first Pivot point in the i-th color difference quantization table, qpc_end_idx [i] is the position of the last Pivot point in the i-th color difference quantization table, qpc_delta [i] Indicates whether the difference between the quantization table values between the first Pivot point and the last Pivot point is 1 or 0. First, the flag separate_qpc_table_flag indicating whether to use the same table for the first color difference and the second color difference is decoded, and if separate_qpc_table_flag is 1, the loop of i = 0.1 is executed, otherwise i = 0. Process only.
(S210) Derivation of the quantization table of the initial interval (from 0 to the first Pivot point).

for (j = 0; j <= qpc_start_idx [i]; j ++)
ChromaQPTable [i] [j] = j
(S220) Derivation of the quantization table between the first Pivot point and the last Pivot point.

for (j = qpc_start_idx + 1; j <= qpc_end_idx; j ++)
ChromaQPTable [i] [j] = ChromaQPTable [i] [j-1] + qpc_delta [i] [j]
(S230) Derivation of the quantization table for the final interval (from the last Pivot point to the end point).

for (j = qpc_end_idx + 1; j <69; j ++)
deltaEnd = qpc_end_idx --ChromaQPTable [qpc_end_idx]
ChromaQPTable [i] [j] = j --deltaEnd
When separate_qpc_table_flag is 0, the first color difference quantization table is copied to the second color difference quantization table.

ChromaQPTable [1] [j] = ChromaQPTable [0] [j] j = 0..69
(Method of deriving the quantization table of joint color difference residual coding 1)
FIG. 16 is a diagram showing a method of deriving the quantization table used for the joint color difference residual coding of the present embodiment.

When joint_cbcr_qp_table_idx == 0, the quantization parameter derivation unit 3026 derives the quantization table ChromaQPTable [2] [] for the joint color difference residual coding from the first color difference quantization table ChromaQPTable [0] []. joint_cbcr_qp_table_idx is a color difference quantization table mode that notifies the color difference quantization table to be referenced to derive ChromaQPTable [2] [].

ChromaQPTable [2] [j] = ChromaQPTable [0] [j] j = 0..num_points_in_qp_table [0] -1
When joint_cbcr_qp_table_idx == 1, the quantization parameter derivation unit 3026 derives the quantization table ChromaQPTable [2] [] of the joint color difference residual coding from the second color difference quantization table ChromaQPTable [0] [].

ChromaQPTable [2] [j] = ChromaQPTable [1] [j] j = 0..num_points_in_qp_table [1] -1
Alternatively, it may be derived by the following equation.

ChromaQPTable [2] [j] = ChromaQPTable [joint_cbcr_qp_table_idx] [j] j = 0..num_points_in_qp_table [joint_cbcr_qp_table_idx] -1
Here, num_points_in_qp_table [joint_cbcr_qp_table_idx] = 64 may be used.

(Method 2 for deriving the quantization table for joint color difference residual coding)
The quantization parameter derivation unit 3026 may derive the quantization table of the above-mentioned joint color difference residual coding by the following processing.

In the case of joint_cbcr_qp_table_idx == 2, the quantization parameter derivation unit 3026 uses the joint color difference residual code from the first color difference quantization table ChromaQPTable [0] [] and the second color difference quantization table ChromaQPTable [1] []. Derivation of the quantization table ChromaQPTable [2] [].

ChromaQPTable [2] [j] = (ChromaQPTable [1] [j] + ChromaQPTable [0] [j]) / 2 j = 0..num_points_in_qp_table [0] -1
The averaging process of the above equation may be performed by a shift operation, or a constant for rounds, for example, 1 may be added. For example, the following processing may be performed.

ChromaQPTable [2] [j] = (ChromaQPTable [1] [j] + ChromaQPTable [0] [j] + 1) >> 1 j = 0..num_points_in_qp_table [0] -1
In the above, ChromaQPTable [2] [] is a configuration derived from the average value of the quantization table for Cb and the quantization table for Cr, but other configurations may be used.

In decoding the conversion coefficient of the target TU, the quantization parameter derivation unit 3026 includes a quantization parameter qPY for brightness (cIdx = 0), a quantization parameter qPCb for the first color difference (cIdx = 1), and a second color difference (cIdx).
Derivation of the quantization parameter qPCr of = 2) and the quantization parameter qPCbCr of the joint color difference residual coding (tu_joint_cbcr_flag! = 0).

The quantization parameter derivation unit 3026 derives the luminance quantization parameter qPY. Specifically, at the beginning of the slice, the value of SliceQPY decoded from the slice header is set to qPY. Otherwise, CuQPDeltaVal is added to the predicted value of qPY qQPYPred to derive qPY. CuQPDeltaVal is the difference value of the luminance quantization parameter.

qPY = qPYPred + CuQPDeltaVal
Further, in order to keep the value after addition within a certain range as described below, wraparound processing using the remainder calculation may be performed.

qPY = (qPYPred + CuQPDeltaVal + 64 + 2 * QpBdOffsetY)% (64 + QpBdOffsetY) --QpBdOffsetY
Here, QpBdOffsetY is an offset value that defines the range of luminance quantization parameters.

Further, the offset is added to derive the luminance quantization parameter.

qPY = qPY + QpBdOffsetY
(Color difference and joint quantization parameter derivation)
The quantization parameter derivation unit 3026 adds the offset (for example, pps_cb_qp_offset, slice_cb_qp_offset) transmitted in PPS and the slice header to the luminance quantization parameter qPY, and adds the intermediate value (intermediate quantization parameter) qPICb of qPCb and qPCr qPCbCr. , QPICr, qPICbCr are derived.

qPICb = qPY + pps_cb_qp_offset + slice_cb_qp_offset
qPICr = qPY + pps_cb_qp_offset + slice_cr_qp_offset
qPICbCr = qPY + pps_cb_cr_qp_offset + slice_cb_cr_qp_offset
Further clipping may be performed here.

qPICb = Clip3 (-QpBdOffsetC, 63 --QpBdOffsetC, qPY + pps_cb_qp_offset + slice_cb_qp_offset)
qPICr = Clip3 (-QpBdOffsetC, 63 --QpBdOffsetC, qPY + pps_cb_qp_offset + slice_cr_qp_offset)
qPICbCr = Clip3 (-QpBdOffsetC, 63 --QpBdOffsetC, qPY + pps_cb_cr_qp_offset + slice_cb_cr_qp_offset)
The quantization parameter derivation unit 3026 uses qPCb, qPCr using the first color difference quantization table ChromaQPTable [0], the second color difference quantization table ChromaQPTable [1], and the joint color difference residual coding quantization table ChromaQPTable [2]. Derivation of qPCbCr.

qPCb = ChromaQPTable [0] [qPICb] (Equation QP-1)
qPCr = ChromaQPTable [1] [qPICr]
qPCbCr = ChromaQPTable [2] [qPICbCr]
Further, the offset value QpBdOffsetC may be added.

qPCb = qPCb + QpBdOffsetC
qPCr = qPCr + QpBdOffsetC
qPCbCr = qPCbCr + QpBdOffsetC
(Color difference and joint quantization parameter derivation example 2)
FIG. 17 is a diagram showing a method of deriving the quantization parameter used for the joint color difference residual coding of the present embodiment.

The quantization parameter derivation unit 3026 derives the quantization parameters qPCb and qPCr qPCbCr using the first color difference quantization table ChromaQPTable [0] and the second color difference quantization table ChromaQPTable [1].

qPCb = ChromaQPTable [0] [qPICb]
qPCr = ChromaQPTable [1] [qPICr]
The quantization parameter derivation unit 3026 derives qPCbCr from the first color difference quantization table ChromaQPTable [0] when joint_cbcr_qp_table_idx == 0.

qPCbCr = ChromaQPTable [0] [qPICb]
That is, qPCbCr = qPICb, and the quantization parameter of the first color difference is set to the quantization parameter for joint color difference residual coding.

The quantization parameter derivation unit 3026 derives qPCbCr from the second color difference quantization table ChromaQPTable [1] when joint_cbcr_qp_table_idx == 1.

qPCbCr = ChromaQPTable [1] [qPICb]
That is, qPCbCr = qPICr, and the quantization parameter of the second color difference is set to the quantization parameter for joint color difference residual coding.

Alternatively, it may be derived as follows.

qPCbCr = ChromaQPTable [joint_cbcr_qp_table_idx] [qPICb]
Further, in the case of joint_cbcr_qp_table_idx == 2, qPCbCr may be derived from the average value of the first color difference quantization table ChromaQPTable [0] and the second color difference quantization table ChromaQPTable [1].

qPCbCr = (ChromaQPTable [1] [qPICb] + ChromaQPTable [2] [qPICr]) / 2
Further, the following processing may be performed.

qPCbCr = (qPICb + qPICr + 1) >> 1
Further, the offset value QpBdOffsetC may be added.

qPCb = qPCb + QpBdOffsetC
qPCr = qPCr + QpBdOffsetC
qPCbCr = qPCbCr + QpBdOffsetC
(Color difference and joint quantization parameter derivation example 3)
In (color difference and joint quantization parameter derivation), the quantization parameter derivation unit 3026 uses the quantization table information notified by the encoded data to use the first color difference quantization table ChromaQPTable [0] and the second color difference quantization table. ChromaQPTable [1] and the quantization table ChromaQPTable [2] for joint color difference residual coding were derived. Using these quantization tables, the quantization parameters qPCb and qPCr qPCbCr were derived.

In the present embodiment, the quantization parameter derivation unit 3026 derives the quantization parameter of the joint color difference residual coding by using the default color difference quantization table. Figure 18 shows an example of the default color difference quantization table. FIG. 18 (a) is the default quantization table ChromaDefaultQPTable [0] for the first color difference, and FIG. 18 (b) is the default quantization table ChromaDefaultQPTable [1] for the second color difference.

In the syntax table of FIG. 15, sps_default_qpc_table_flag is a flag indicating whether to use the default quantization table for deriving the quantization parameter. When the default quantization table is not used, the quantization table derived from the quantization information notified by the coded data is used. default_qpc_idc is an index indicating how to derive the default quantization table ChromaDefaultQPTable [2] for joint color difference residual coding when the default quantization table is used. The parameter decoding unit 302 decodes these syntaxes. The quantization parameter derivation unit 3026, for example, when default_qpc_idc = 0, ChromaDefaultQPTable [
Set 0] to ChromaDefaultQPTable [2], if default_qpc_idc = 1, set ChromaDefaultQPTable [1] to ChromaDefaultQPTable [2], and if default_qpc_idc = 2, set the average value of ChromaDefaultQPTable [0] and ChromaDefaultQPTable [1] to ChromaDefaultQPTable Set to [2].

if (default_qpc_idc <2)
ChromaDefaultQPTable [2] [j] = ChromaQPTable [default_qpc_idc] [j] j = 0..63
else else
ChromaDefaultQPTable [2] [j] = (ChromaQPTable [0] [j] + ChromaQPTable [1] [j]) / 2 j = 0..63
Alternatively, it may be as follows.

if (default_qpc_idc <2)
ChromaDefaultQPTable [2] [j] = ChromaQPTable [default_qpc_idc] [j] j = 0..63
else else
ChromaDefaultQPTable [2] [j] = (ChromaQPTable [0] [j] + ChromaQPTable [1] [j] +1) >> 1
j = 0..63
The quantization parameter derivation unit 3026 derives the quantization parameters using these default quantization tables. In the quantization table of FIG. 18, qPi corresponds to qPICb and QPc corresponds to qPCb, qPCr, and qPCbCr. In this embodiment, (formula QP-1) is replaced with (formula QP-2).

qPCb = ChromaDefaultQPTable [0] [qPICb] (Equation QP-2)
qPCr = ChromaDefaultQPTable [1] [qPICr]
qPCbCr = ChromaDefaultQPTable [2] [qPICbCr]
By using the default quantization table to derive the quantization parameters of the color difference, the code amount of the quantization table information can be reduced.

(Color difference and joint quantization parameter derivation example 4)
In this embodiment, another example of the default quantization table will be described. FIG. 18 (c) shows the HDR HLG method default quantization table ChromaDefaultQPTable [1], and FIG. 18 (d) shows the HDR PQ method default quantization table ChromaDefaultQPTable [2]. HLG (Hybrid Log Gamma) and PQ (Perceptual Quantization) are gamma curves defined by BT.2100. (a) is the SDR default quantization table ChromaDefaultQPTable [0].

In the syntax table of FIG. 15, default_qpc_idc is an index indicating which default quantization table is used for the color difference quantization table.

The quantization parameter derivation unit 3026 derives the quantization parameters using these default quantization tables. In this embodiment, (Equation QP-2) is replaced with (Equation QP-3).

qPCb = ChromaDefaultQPTable [default_qpc_idc] [qPICb] (Equation QP-3)
qPCr = ChromaDefaultQPTable [default_qpc_idc] [qPICr]
qPCbCr = ChromaDefaultQPTable [default_qpc_idc] [qPICbCr]
By notifying the default quantization table corresponding to various gamma curves, an appropriate quantization table suitable for the decoded image can be used.

FIG. 13 is a block diagram showing the configuration of the inverse quantization / inverse conversion unit 311 of the present embodiment. The inverse quantization / inverse conversion unit 311 is composed of a scaling unit 31111, an inverse secondary conversion unit 31121, an inverse core conversion unit 31123, and a joint error derivation unit 3113.

(Scaling section 31111)
The scaling unit 31111 uses the quantization parameter derived in the quantization parameter derivation unit 3026 to scale the conversion coefficient decoded by the TU decoding unit using the weight in coefficient units.

Here, the quantization parameter qP is derived as follows using the color component cIdx of the target conversion coefficient and the joint color difference residual coding flag tu_joint_cbcr_flag.

qP = qPY (cIdx == 0)
qP = qPCb (cIdx == 1 && tu_joint_cbcr_flag == 0)
qP = qPCr (cIdx == 2 && tu_joint_cbcr_flag == 0)
qP = qPCbCr (tu_joint_cbcr_flag! = 0)
When the transformation skip is enabled (transform_skip == 1), the scaling unit 31111 performs scaling by the following formula.

r [x] [y] = d [x] [y] << tsShift
Where tsShift = 5 + ((log2 (nTbW) + log2 (nTbH)) / 2).

In cases other than the above, the quantization matrix m [x] [y] and the scaling factor ls [x] [y] are derived by the following equations.

ls [x] [y] = (m [x] [y] * levelScale [(qP + 1)% 6]) << (qP / 6)
Alternatively, it may be derived by the following formula.

ls [x] [y] = (m [x] [y] * levelScale [qP% 6]) << (qP / 6)
Where levelScale [] = {40, 45, 51, 57, 64, 72}.

The value of the quantization matrix m [x] [y] may be decoded from the coded data, or m [x] [y] = 16 may be used as the uniform quantization.

The scaling unit 31111 derives dnc [] [] from the product of the scaling factor ls [] [] and the decoded conversion coefficient TransCoeffLevel, and performs inverse quantization.

dnc [x] [y] = (TransCoeffLevel [xTbY] [yTbY] [cIdx] [x] [y] * ls [x] [y] * rectNorm + bdOffset) >> bdShift
Finally, the scaling unit 31111 clips the inverse quantized conversion coefficient and derives d [x] [y].

d [x] [y] = Clip3 (CoeffMin, CoeffMax, dnc [x] [y])
d [x] [y] is transmitted to the reverse core conversion unit 31123 or the reverse secondary conversion unit 31121. The secondary transformation unit (second transformation unit) 31121 applies the secondary transformation to the transformation coefficient d [] [] after the inverse quantization and before the core transformation.

The inverse secondary conversion unit 31121 applies a conversion using a transformation matrix to a part or all of the conversion coefficients d [] [] received from the scaling unit 31111, thereby causing a correction conversion coefficient (second conversion unit). (Conversion coefficient after conversion by) d [] [] is restored. The inverse secondary conversion unit 31121 applies the inverse secondary conversion to the conversion coefficient d [] [] of a predetermined unit for each conversion unit TU. The secondary transformation is applied only in the intra CU, and the transformation basis is determined with reference to the intrapred mode. The selection of the conversion basis will be described later. The inverse secondary conversion unit 31121 outputs the restored modified conversion coefficient d [] [] to the inverse core conversion unit 31123.

The core conversion unit 31123 acquires the conversion coefficient d [] [] or the correction conversion coefficient d [] [] restored by the inverse secondary conversion unit 31121, performs conversion, and derives the prediction error r [] []. .. Then, the r [] [] is scaled according to the bit depth, and the error resSamples [] [] with the same accuracy as the predicted image derived by the predicted image generation unit 308 is derived. For example, scaling is expressed as:

resSamples [x] [y] = (r [x] [y] + (1 << (bdShift -1))) >> bdShift (expression BD-1)
bdShift = Max (20 --bitDepth, 0)
In this operation, resSamples [] [] with bitDepth accuracy is obtained by shift operation from r [] [] with 20-bit accuracy. The value indicating the accuracy is not limited to 20, and other values between 8 and 24 may be used (the same shall apply hereinafter). Scaling according to bitDepth may be performed by providing a bit depth scale unit (not shown). The derived error is output to the addition unit 312.

The joint error derivation unit 3113 uses the prediction error r [] [] of the first color component (cIdx = cIdx0).
Is used to derive the prediction error resSamples [] [] for the second color component (eg cIdx = cIdx1). Color components can be identified by cIdx, for example, cIdx = 0 indicates luminance, cIdx = 1 indicates color difference Cb, and cIdx = 2 indicates color difference Cr. Note that the joint error derivation unit does not process the brightness, so cIdx0 and cIdx1 are 1 or 2 (the same applies hereinafter). resSamples [] [] with cIdx == 1 is written as resSamplesCb [] [] or resCb [] []. resSamples [] [] of cIdx == 2 is written as resSamplesCr [] [] or resCr [] []. Further, the joint error derivation unit 3113 uses the addition and difference of the prediction error r [] [] of the two color components (cIdx = cIdx0, cIdx = cIdx1) to use the two color components (cIdx = cIdx0, cIdx = cIdx1). ) ResSamples [] [] may be derived. Further, the joint error derivation unit 3113 uses the prediction error r [] [] of the first color component (cIdx = cIdx0) by the shift operation depending on the bitDepth of the image as described later, and uses the second color component. You may derive resSamples [] [] of (for example, cIdx = cIdx1). The variables cIdx0 and cIdx1 indicating a specific color component may be 1, 2 (Cr is derived from Cb) or 2, 1 (Cb is derived from Cr). Also, when cIdx0 = 1, the relationship of cIdx1 = 2 is satisfied, and when cIdx0 = 2, the relationship of cIdx1 = 1 is satisfied. That is, the relationship of cIdx1 = 3-cIdx0 is satisfied.

(Decoding process of quantization prediction error)
In the following, the decoding process of the quantization prediction error will be described more specifically.

(Decryption processing example)
In this example, the TU decoding unit 3024 decodes one quantization prediction error (also called a prediction residual, or simply a residual) to derive a prediction residual for a plurality of color components (Cb and Cr as an example). Performs joint color difference decoding processing.

In many cases, the predicted residuals for multiple color components are correlated with each other. In the joint color difference decoding process, the predicted residuals of Cb and Cr are not individually encoded, only one of the color components (first color component) is encoded, and the other color component (second color component) is encoded. The prediction error of is derived from the prediction error of the first color component. As a result, the amount of coded data can be reduced by performing the joint color difference decoding process.

Further, as will be described later, the TU decoding unit 3024 determines the relational expression between the plurality of color components for each mode (joint mode), and sets a sign flag indicating a positive or negative code used in the relational expression. Derived for each mode.

In this example, first, the header decoding unit 3020 decodes a plurality of sine flags in the header obtained by dividing the picture into segments (for example, slice header (slice_header) and tile group header (tile_group_header)).

As an example, as shown in FIG. 8, the following three sign flags are decoded.
・ Joint_mode1_cb_cr_sign_flag
・ Joint_mode2_cb_cr_sign_flag
・ Joint_mode3_cb_cr_sign_flag
These flags are used to identify a plurality of positive and negative codes referred to in the joint color difference decoding process described later.

Note that FIG. 8 is an example of a syntax table relating to a plurality of sign flags, and the present embodiment is not limited to this. For example, as shown in FIG. 9, a plurality of sine flags may be decoded as an array as shown below.
・ Joint_cb_cr_sign_flag [0]
・ Joint_cb_cr_sign_flag [1]
・ Joint_cb_cr_sign_flag [2]
Each of these flags corresponds to each of the above-mentioned joint_mode1_cb_cr_sign_flag to joint_mode3_cb_cr_sign_flag as an example.

Subsequently, the TU decoding unit 3024 decodes the following in block units.
-Flag tu_joint_chroma_residual_flag [x0] [y0] indicating whether to encode the color difference with the joint color difference
-Block flag information (tu_cbf_cb [x0] [y0], tu_cbf_cr [x0] [y0])
Block flag information tu_cbf_cb and tu_cbf_cr are flags that indicate whether or not there is information on the quantization prediction error resSamples corresponding to Cb and Cr (whether or not there is one or more non-zero conversion coefficients). May have the meaning of. A combination of tu_cbf_cb and tu_cbf_cr may be used to indicate whether or not information on the prediction error resSamples exists.

FIG. 10 shows the syntax table of transform_unit () including the above flag and block flag information. As an example, the TU decoding unit 3024 decodes tu_cbf_cb [x0] [y0] and tu_cbf_cr [x0] [y0] when the tree type is SINGLE_TREE or DUAL_TREE_CHROMA. Here, "if ()" in the figure indicates that some condition may be added (the same applies to the following figures). If tu_cbf_cb [x0] [y0] is true (the TU of Cb has a non-zero factor), or if tu_cbf_cr [x0] [y0] is true (the TU of Cr has a non-zero factor). Decrypt tu_joint_chroma_residual_flag [x0] [y0].

FIG. 11 shows the relationship between the values of tu_cbf_cb [x0] [y0] and tu_cbf_cr [x0] [y0] and the joint mode (joint_chroma_coding_mode). Joint mode 1 (mode1) is selected when tu_cbf_cb is true (1) and tu_cbf_cr is false (0), and joint mode 2 (mode2) is selected when tu_cbf_cb is true and tu_cbf_cr is true. When tu_cbf_cb is false and tu_cbf_cr is true, joint mode 3 (mode3) is selected.

Returning to FIG. 10 again, the TU decoding unit 3024 decodes the first color difference residual residual_coding (xC, yC, Log2 (wC), Log2 (hC), 1) when tu_cbf_cb [x0] [y0] = 1. To do.

Here, wC and hC are the sizes of the color difference conversion unit TU. For example, when the size of the luminance TU is tbWidth and tbHeight and the ratio of the luminance and color difference width and height is SubWidthC and SubHeightC, it is derived as follows. You may.

wC = tbWidth / SubWidthC
hC = tbHeight / SubHeightC
Even when tu_joint_chroma_residual_flag [x0] [y0] = 1, the first color difference residual residual_coding (xC, yC, Log2 (wC), Log2 (hC), 1) is decoded.

When tu_cbf_cr [x0] [y0] = 1 and tu_joint_chroma_residual_flag [x0] [y0] = 0,
Decode the second color difference residual residual_coding (xC, yC, Log2 (wC), Log2 (hC), 2).

When the result obtained by decoding residual_coding () as described above is expressed as res [] [], the TU decoding unit 3024 further performs the following derivation processing to obtain the quantization prediction error of the target color component. Derivation of resSamples [] [].
-When the mode is 2 and cIdx = 2, the residual resSamples of Cr is decoded by the following formula.
resSamples [x] [y] = (joint_mode2_cb_cr_sign_flag? -1: 1) * res [x] [y]
-When the mode is 1 and cIdx = 2, the residual resSamples of Cr is decoded by the following formula.
resSamples [x] [y] = (joint_mode1_cb_cr_sign_flag? -1: 1) * res [x] [y]) >> 1
-When the mode is 3 and cIdx = 1, the residual resSamples of Cb is decoded by the following formula.
resSamples [x] [y] = (joint_mode3_cb_cr_sign_flag? -1: 1) * res [x] [y]) >> 1
As is clear from the above derivation formula, in this example, the sine coefficient (sometimes called the sine flag) multiplied by res [x] [y] on the right side of the above derivation formula is decoded for each joint mode. To. In the above derivation formula, cIdx is a value indicating a color component, as an example, cIdx = 0 indicates a luminance component Y, cIdx = 1 indicates a color difference component Cb, and cIdx = 2 indicates a color difference component Cr. The configuration of this specification is also applicable when the color space is RGB or GBR instead of YCbCr. In this case, replace Y, Cb, Cr with R, G, B or G, B, R.

Therefore, among the quantization prediction errors derived as described above, the quantization prediction error corresponding to the color difference component Cb is expressed as resSamplesCb, and the quantization prediction error corresponding to the color difference component Cr is expressed as resSamplesCr. The quantization prediction error of can be derived from the following relational expression for each joint mode. In the following description of the present specification, the process of multiplying by 1/2 may be replaced with a 1-bit right shift (for example, resCb = -resCr >> 1).

mode2: resSamplesCr = CSign2 * resCb
mode1: resSamplesCr = CSign1 * resCb / 2
mode3: resSamplesCb = CSign3 * resCr / 2
Here, the sine flags CSign2, CSign1, and CSign3 correspond to the following parts in the derivation formula of the quantization prediction error, respectively.

(joint_mode2_cb_cr_sign_flag? -1: 1),
(joint_mode1_cb_cr_sign_flag? -1: 1),
(joint_mode3_cb_cr_sign_flag? -1: 1)
resCb and resCr are the quantization prediction error ress decoded as the information of Cb and Cr, respectively. That is, the above processing can also be regarded as a transformation or update of the quantization prediction error.

That is, the derivation process of the TU decoding unit 3024 may be replaced with the following.
-When the mode is 2 and cIdx = 2, the predicted residual is decoded by the following formula.

resSamplesCb [x] [y] = res [x] [y]
resSamplesCr [x] [y] = (joint_mode2_cb_cr_sign_flag? -1: 1) * res [x] [y]
-When the mode is 1 and cIdx = 2, the predicted residual is decoded by the following formula.

resSamplesCb [x] [y] = res [x] [y]
resSamplesCr [x] [y] = (joint_mode1_cb_cr_sign_flag? -1: 1) * (res [x] [y]) >> 1)
-When the mode is 3 and cIdx = 1, the predicted residual is decoded by the following formula.

resSamplesCr [x] [y] = res [x] [y]
resSamplesCb [x] [y] = (joint_mode3_cb_cr_sign_flag? -1: 1) * (res [x] [y]) >> 1)
In this example, the sine coefficient (sine flag) is decoded for each joint mode as described above. As a result, compared to the case where the sine flag is fixedly used for each slice or picture, in other words, the more appropriate target color component is compared to the case where the fixed value is used for each slice or picture regardless of the mode. Quantization prediction error resSamples [] [] can be derived.

(Configuration of moving image encoding device)
Next, the configuration of the moving image coding device 11 according to the present embodiment will be described. FIG. 12 is a block diagram showing the configuration of the moving image coding device 11 according to the present embodiment. The moving image coding device 11 includes a prediction image generation unit 101, a subtraction unit 102, a conversion / quantization unit 103, an inverse quantization / inverse conversion unit 105, an addition unit 106, a loop filter 107, and a prediction parameter memory (prediction parameter storage unit). , Frame memory) 108, reference picture memory (reference image storage unit, frame memory) 109, coding parameter determination unit 110, parameter coding unit 111, and entropy coding unit 104.

The prediction image generation unit 101 generates a prediction image for each CU, which is a region in which each picture of the image T is divided. The prediction image generation unit 101 has the same operation as the prediction image generation unit 308 described above, and the description thereof will be omitted.

The subtraction unit 102 subtracts the pixel value of the predicted image of the block input from the prediction image generation unit 101 from the pixel value of the image T to generate a prediction error. The subtraction unit 102 outputs the prediction error to the conversion / quantization unit 103.

The conversion / quantization unit 103 calculates the conversion coefficient by frequency conversion for the prediction error input from the subtraction unit 102, and derives the quantization conversion coefficient by quantization. The conversion / quantization unit 103
The quantization conversion coefficient is output to the entropy coding unit 104 and the inverse quantization / inverse conversion unit 105.

The inverse quantization / inverse conversion unit 105 is the inverse quantization / inverse conversion unit 311 (FIG. 6) in the moving image decoding device 31.
The same as above, and the description thereof will be omitted. The calculated prediction error is output to the addition unit 106.

A quantization conversion coefficient is input to the entropy coding unit 104 from the conversion / quantization unit 103, and a coding parameter is input from the parameter coding unit 111. Coding parameters include, for example, reference picture indexes refIdxLX, mvp_LX_idx, mvdLX, predMode, and merge_idx.

The entropy coding unit 104 entropy-codes the division information, the prediction parameters, the quantization conversion coefficient, and the like to generate a coded stream Te and outputs it.

The parameter coding unit 111 includes a header coding unit 1110 (not shown), a CT information coding unit 1111 and a CU.
It includes a coding unit 1112 (prediction mode coding unit), an inter prediction parameter coding unit 112, and an intra prediction parameter coding unit 113. The CU coding unit 1112 further includes a TU coding unit 1114.

The outline operation of each module will be described below. The parameter coding unit 111 performs parameter coding processing such as header information, division information, prediction information, and quantization conversion coefficient.

The CT information coding unit 1111 encodes QT, MT (BT, TT) division information and the like from the coded data.

The CU coding unit 1112 encodes CU information, prediction information, split_transform_flag, cbf_cb, cbf_cr, cbf_luma and the like.

The TU coding unit 1114 encodes the QP update information (quantization correction value) and the quantization prediction error (residual_coding) when the TU includes a prediction error.

The CT information coding unit 1111, CU coding unit 1112, and TU coding unit 1114 include inter-prediction parameters (predMode, merge_flag, merge_idx, inter_pred_idc, refIdxLX, mvp_LX_idx, mvdLX), intra-prediction parameters (intra_luma_pred_flag, intra_luma_mpm_lum_flag, intra_luma_mpm_. ), Quantization conversion factor, resJoint1, resJoint2, sine flag, tu_joint_chroma_residual_flag [x0] [y0], tu_joint_chroma_residual_mode [x0] [y0], tu_cbf_cb [x0] [y0], tu_cbf_cr [x0] [y0], tu_cbf_cr [x0] The syntax elements such as joint_cb_cr_mode, JointCbCrWeightFlag, joint_cb_cr_dir, joint_cb_cr_mode_idx, tu_joint_stereo_mode [x0] [y0] are supplied to the entropy encoding unit 104.

The addition unit 106 generates a decoded image by adding the pixel value of the prediction image of the block input from the prediction image generation unit 101 and the prediction error input from the inverse quantization / inverse conversion unit 105 for each pixel. The addition unit 106 stores the generated decoded image in the reference picture memory 109.

The loop filter 107 applies a deblocking filter, SAO, and ALF to the decoded image generated by the addition unit 106. The loop filter 107 does not necessarily have to include the above three types of filters, and may have, for example, a configuration of only a deblocking filter.

The prediction parameter memory 108 stores the prediction parameters generated by the coding parameter determination unit 110 at positions predetermined for each target picture and CU.

The reference picture memory 109 stores the decoded image generated by the loop filter 107 at a predetermined position for each target picture and CU.

The coding parameter determination unit 110 selects one set from the plurality of sets of coding parameters. The coding parameter is the above-mentioned QT, BT or TT division information, prediction parameter, or a parameter to be coded generated in connection with these. The prediction image generation unit 101 generates a prediction image using these coding parameters.

The coding parameter determination unit 110 calculates an RD cost value indicating the magnitude of the amount of information and the coding error for each of the plurality of sets. The coding parameter determination unit 110 selects the set of coding parameters that minimizes the calculated cost value. As a result, the entropy coding unit 104 outputs the selected set of coding parameters as the coding stream Te. The coding parameter determination unit 110 stores the determined coding parameter in the prediction parameter memory 108.

A part of the moving image coding device 11 and the moving image decoding device 31 in the above-described embodiment, for example, the entropy decoding unit 301, the parameter decoding unit 302, the loop filter 305, the predicted image generation unit 308, and the inverse quantization / reverse. Conversion unit 311, Addition unit 312, Prediction image generation unit 101, Subtraction unit 102, Conversion / quantization unit 103, Entropy coding unit 104, Inverse quantization / inverse conversion unit 105, Loop filter 107, Coding parameter determination unit 110 , The parameter coding unit 111 may be realized by a computer. In that case, the program for realizing this control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read by the computer system and executed. The "computer system" referred to here is a computer system built into either the moving image coding device 11 or the moving image decoding device 31, and includes hardware such as an OS and peripheral devices. Further, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, or a storage device such as a hard disk built in a computer system. Furthermore, a "computer-readable recording medium" is a medium that dynamically holds a program for a short period of time, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In that case, a program may be held for a certain period of time, such as a volatile memory inside a computer system serving as a server or a client. Further, the above-mentioned program may be a program for realizing a part of the above-mentioned functions, and may further realize the above-mentioned functions in combination with a program already recorded in the computer system.

Further, a part or all of the moving image coding device 11 and the moving image decoding device 31 in the above-described embodiment may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each functional block of the moving image coding device 11 and the moving image decoding device 31 may be made into a processor individually, or a part or all of them may be integrated into a processor. Further, the method of making an integrated circuit is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Further, when an integrated circuit technology that replaces an LSI appears due to advances in semiconductor technology, an integrated circuit based on this technology may be used.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like are made without departing from the gist of the present invention. It is possible to do.

[Application example]
The moving image coding device 11 and the moving image decoding device 31 described above can be mounted on and used in various devices for transmitting, receiving, recording, and reproducing moving images. The moving image may be a natural moving image captured by a camera or the like, or an artificial moving image (including CG and GUI) generated by a computer or the like.

First, it will be described with reference to FIG. 2 that the moving image coding device 11 and the moving image decoding device 31 described above can be used for transmitting and receiving moving images.

FIG. 2 shows a block diagram showing the configuration of the transmission device PROD_A equipped with the moving image coding device 11. As shown in the figure, the transmission device PROD_A has a coding unit PROD_A1 that obtains coded data by encoding a moving image, and a modulation signal by modulating a carrier with the coded data obtained by the coding unit PROD_A1. It includes a modulation unit PROD_A2 to obtain and a transmission unit PROD_A3 to transmit the modulation signal obtained by the modulation unit PROD_A2. The moving image coding device 11 described above is used as the coding unit PROD_A1.

The transmitter PROD_A has a camera PROD_A4 for capturing a moving image, a recording medium PROD_A5 for recording a moving image, an input terminal PROD_A6 for inputting a moving image from the outside, and a moving image as a source of the moving image to be input to the coding unit PROD_A1. , An image processing unit A7 for generating or processing an image may be further provided. In the figure, the configuration in which the transmitter PROD_A is provided with all of these is illustrated, but some of them may be omitted.

The recording medium PROD_A5 may be a recording of an unencoded moving image, or a moving image encoded by a recording coding method different from the transmission coding method. It may be a thing. In the latter case, a decoding unit (decoding unit) that decodes the coded data read from the recording medium PROD_A5 between the recording medium PROD_A5 and the coding unit PROD_A1 according to the coding method for recording.
It is advisable to intervene (not shown).

Further, FIG. 2 shows a block diagram showing the configuration of the receiving device PROD_B equipped with the moving image decoding device 31. As shown in the figure, the receiving device PROD_B is obtained by a receiving unit PROD_B1 that receives a modulated signal, a demodulating unit PROD_B2 that obtains coded data by demodulating the modulated signal received by the receiving unit PROD_B1, and a demodulating unit PROD_B2. It includes a decoding unit PROD_B3 that obtains a moving image by decoding the coded data. The moving image decoding device 31 described above is used as the decoding unit PROD_B3.

The receiving device PROD_B is a display PROD_B4 for displaying a moving image, a recording medium PROD_B5 for recording a moving image, and an output terminal for outputting the moving image to the outside as a supply destination of the moving image output by the decoding unit PROD_B3. It may also have PROD_B6. In the figure, the configuration in which the receiving device PROD_B is provided with all of these is illustrated, but some of them may be omitted.

The recording medium PROD_B5 may be used for recording an unencoded moving image, or may be encoded by a recording encoding method different from the transmission coding method. You may. In the latter case, a coding unit (not shown) that encodes the moving image acquired from the decoding unit PROD_B3 according to the recording coding method may be interposed between the decoding unit PROD_B3 and the recording medium PROD_B5.

The transmission medium for transmitting the modulated signal may be wireless or wired. Further, the transmission mode for transmitting the modulated signal may be broadcasting (here, a transmission mode in which the destination is not specified in advance) or communication (here, transmission in which the destination is specified in advance). Refers to an aspect). That is, the transmission of the modulated signal may be realized by any of wireless broadcasting, wired broadcasting, wireless communication, and wired communication.

For example, a broadcasting station (broadcasting equipment, etc.) / receiving station (television receiver, etc.) of terrestrial digital broadcasting is an example of a transmitting device PROD_A / receiving device PROD_B that transmits and receives modulated signals by radio broadcasting. Further, a broadcasting station (broadcasting equipment, etc.) / receiving station (television receiver, etc.) of cable television broadcasting is an example of a transmitting device PROD_A / receiving device PROD_B that transmits and receives modulated signals by wired broadcasting.

In addition, servers (workstations, etc.) / clients (television receivers, personal computers, smartphones, etc.) such as VOD (Video On Demand) services and video sharing services using the Internet are transmitters that send and receive modulated signals via communication. This is an example of PROD_A / receiver PROD_B (usually, in LAN, either wireless or wired is used as a transmission medium, and in WAN, wired is used as a transmission medium). Here, personal computers include desktop PCs, laptop PCs, and tablet PCs. Smartphones also include multifunctional mobile phone terminals.

The client of the video sharing service has a function of decoding the encoded data downloaded from the server and displaying it on the display, as well as a function of encoding the moving image captured by the camera and uploading it to the server. That is, the client of the video sharing service functions as both the transmitting device PROD_A and the receiving device PROD_B.

Next, it will be described with reference to FIG. 3 that the moving image coding device 11 and the moving image decoding device 31 described above can be used for recording and reproducing a moving image.

FIG. 3 shows a block diagram showing the configuration of the recording device PROD_C equipped with the moving image coding device 11 described above. As shown in the figure, the recording device PROD_C has a coding unit PROD_C1 that obtains coded data by encoding a moving image and a writing unit PROD_C2 that writes the coded data obtained by the coding unit PROD_C1 to the recording medium PROD_M. And have. The moving image encoding device 11 described above.
Is used as this coding unit PROD_C1.

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

Further, the recording device PROD_C has a camera PROD_C3 that captures a moving image, an input terminal PROD_C4 for inputting a moving image from the outside, and a reception for receiving the moving image as a source of the moving image to be input to the coding unit PROD_C1. A unit PROD_C5 and an image processing unit PROD_C6 for generating or processing an image may be further provided. In the figure, the configuration provided by the recording device PROD_C is illustrated, but some of them may be omitted.

The receiving unit PROD_C5 may receive an unencoded moving image, or receives coded data encoded by a transmission coding method different from the recording coding method. It may be something to do. In the latter case, it is preferable to interpose a transmission decoding unit (not shown) between the receiving unit PROD_C5 and the coding unit PROD_C1 to decode the coded data encoded by the transmission coding method.

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 moving images). .. In addition, a camcorder (in this case, the camera PROD_C3 is the main source of moving images), a personal computer (in this case, the receiving unit PROD_C5 or the image processing unit C6 is the main source of moving images), and a smartphone (this In this case, the camera PROD_C3 or the receiver PROD_C5 is the main source of moving images) is also an example of such a recording device PROD_C.

Further, FIG. 3 shows a block diagram showing the configuration of the reproduction device PROD_D equipped with the above-mentioned moving image decoding device 31. As shown in the figure, the reproduction device PROD_D includes a reading unit PROD_D1 that reads the coded data written in the recording medium PROD_M, and a decoding unit PROD_D2 that obtains a moving image by decoding the coded data read by the reading unit PROD_D1. , Is equipped. The moving image decoding device 31 described above is used as the decoding unit PROD_D2.

The recording medium PROD_M may be of a type built into the playback device PROD_D, such as (1) HDD or SSD, or (2) such as an SD memory card or USB flash memory. It may be of a type connected to the playback device PROD_D, or may be loaded into a drive device (not shown) built in the playback device PROD_D, such as (3) DVD or BD. Good.

Further, the playback device PROD_D has a display PROD_D3 for displaying the moving image, an output terminal PROD_D4 for outputting the moving image to the outside, and a transmitting unit for transmitting the moving image as a supply destination of the moving image output by the decoding unit PROD_D2. It may also have PROD_D5. In the figure, the configuration in which the playback device PROD_D is provided with all of these is illustrated, but some of them may be omitted.

The transmission unit PROD_D5 may transmit an unencoded moving image, or transmits coded data encoded by a transmission coding method different from the recording coding method. It may be something to do. In the latter case, it is preferable to interpose a coding unit (not shown) that encodes the moving image by a coding method for transmission between the decoding unit PROD_D2 and the transmitting unit PROD_D5.

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

(Hardware realization and software realization)
Further, each block of the moving image decoding device 31 and the moving image coding device 11 described above may be realized by hardware by a logic circuit formed on an integrated circuit (IC chip), or may be realized by a CPU.
It may be realized by software by using (Central Processing Unit).

In the latter case, each of the above devices is a CPU that executes instructions of a program that realizes each function, a ROM (Read Only Memory) that stores the above program, and a RAM (Random) that expands the above program.
Access Memory), a storage device (recording medium) such as a memory for storing the above programs and various data. Then, an object of the embodiment of the present invention is a record in which the program code (execution format program, intermediate code program, source program) of the control program of each of the above devices, which is software for realizing the above-mentioned functions, is recorded readable by a computer. It can also be achieved by supplying a medium to each of the above devices and having the computer (or CPU or MPU) read and execute the program code recorded on the recording medium.

Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic discs such as floppy (registered trademark) discs / hard disks, and CD-ROMs (Compact Disc Read-Only Memory) / MO discs (Magneto-Optical discs). ) / MD (Mini Disc) / DVD (Digital Versatile Disc: registered trademark) / CD-R (CD Recordable) / Blu-ray Disc (registered trademark) and other optical discs, IC cards (memory cards) (Including) / Optical cards and other cards, mask ROM / EPROM (Erasable Programmable Read-Only Memory) / EEPROM (Electrically Erasable and Programmable Read-Only Memory: registered trademark) / Flash ROM and other semiconductor memories, or PLD ( Logic circuits such as Programmable logic device) and FPGA (Field Programmable Gate Array) can be used.

Further, each of the above devices may be configured to be connectable to a communication network, and the above program code may be supplied via the communication network. This communication network is not particularly limited as long as it can transmit the program code. For example, Internet, Intranet, Extranet, LAN (Local Area Network), ISDN (Integrated Services Digital Network), VAN (Value-Added Network), CATV (Community Antenna television / Cable Television) communication network, Virtual Private network (Virtual Private) Network), telephone line network, mobile communication network, satellite communication network, etc. can be used. Further, the transmission medium constituting this communication network may be any medium as long as it can transmit the program code, and is not limited to a specific configuration or type. For example, even wired such as IEEE (Institute of Electrical and Electronic Engineers) 1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared data such as IrDA (Infrared Data Association) and remote control , BlueTooth (registered trademark), IEEE802.11 wireless, HDR (High Data Rate), NFC (Near Field Communication), DLNA (Digital Living Network Alliance: registered trademark), mobile phone network, satellite line, terrestrial digital broadcasting network, etc. It is also available wirelessly. The embodiment of 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.

The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.

The embodiment of the present invention is suitably applied to a moving image decoding device that decodes encoded data in which image data is encoded, and a moving image coding device that generates encoded data in which image data is encoded. be able to. Further, it can be suitably applied to the data structure of the coded data generated by the moving image coding device and referenced by the moving image decoding device.

31 Image decoder
301 Entropy Decryptor
302 Parameter decoder
3020 Header decoder
303 Inter prediction parameter decoding unit
304 Intra Prediction Parameter Decoder
308 Prediction image generator
309 Inter-prediction image generator
310 Intra prediction image generator
311 Inverse quantization / inverse conversion
312 Addition part
11 Image coding device
101 Predictive image generator
102 Subtraction section
103 Conversion / Quantization Department
104 Entropy encoding section
105 Inverse quantization / inverse conversion
107 Loop filter
110 Coded parameter determination unit
111 Parameter encoding section
112 Inter-prediction parameter encoding section
113 Intra Prediction Parameter Encoding Unit
1110 Header encoding
1111 CT information coding unit
1112 CU encoding unit (prediction mode encoding unit)
1114 TU coder
31111 Scaling section
31121 Inverse secondary converter
31123 Reverse core converter
3113 Joint error derivation part

Claims (4)

An image decoding device provided with a decoding unit that decodes the predicted residuals.
The decoding unit
It has a joint color difference residual coding mode that decodes the predicted residuals of the first color component and derives the predicted residuals for the second color component.
It is equipped with a quantization parameter derivation unit that derives the color difference quantization parameter from the intermediate quantization parameter derived from the brightness quantization parameter with reference to the color difference quantization table.
The quantization parameter derivation unit derives the color difference quantization table mode, and depending on the color difference quantization table mode, the first color difference quantization table or the first color difference quantization table is added to the color difference quantization table of the joint color difference residual coding mode. An image decoding device characterized by setting a second color difference quantization table. The above-mentioned quantization parameter derivation unit uses the color difference quantization table used in the joint color difference residual coding mode as the first color difference color difference quantization table and the second color difference color difference quantization according to the color difference quantization table mode. The image decoding apparatus according to claim 1, wherein the image decoding device is derived by using a table. An image decoding device provided with a decoding unit that decodes the predicted residuals.
The decoding unit
It has a joint color difference residual coding mode that decodes the predicted residuals of the first color component and derives the predicted residuals for the second color component.
It is equipped with a quantization parameter derivation unit that derives the color difference quantization parameter from the intermediate quantization parameter derived from the brightness quantization parameter with reference to the color difference quantization table.
The above-mentioned quantization parameter derivation unit derives the color difference quantization table mode, and depending on the color difference quantization table mode, the first color difference quantization parameter or the color difference quantization parameter is used as the color difference quantization parameter of the joint color difference residual coding mode. , An image decoding apparatus characterized in that the quantization parameter of the second color difference is set. The above-mentioned quantization parameter derivation unit uses the quantization parameter used in the joint color difference residual coding mode according to the color difference quantization table mode, the first color difference quantization parameter and the second color difference quantization parameter. The image decoding apparatus according to claim 3, wherein the image decoding device is derived.

Images