JP2014099672A - Decoder, encoder, and data structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform suitable filter processing on the color difference components of an image.SOLUTION: An adaptive filter 30 comprises: a color difference adaptive filter unit 32 composed of a Cr filter processing unit 322 for performing adaptive filter processing on a color difference component Cr and a Cb filter processing unit 323 for performing adaptive filter processing on a color difference component Cb; and a color difference adaptive filter information decoding unit 31 for decoding filter coefficient information to be used for the adaptive filter processing of the color difference components.

Description

  The present invention relates to an encoding device and an decoding device including an image filter device that performs image filtering. The present invention also relates to a data structure of encoded data decoded by such a decoding device.

  In order to efficiently transmit or record a moving image, a moving image encoding device (encoding device) that generates encoded data by encoding the moving image, and decoding by decoding the encoded data A video decoding device (decoding device) that generates an image is used. As a specific moving picture encoding method, for example, H.264 is used. H.264 / MPEG-4. There is AVC.

  In this encoding method, an input image is divided into one luminance component (luminance component Y) and two color difference components (color difference component Cr and color difference component Cb, respectively), and encoding / decoding processing is performed.

  Usually, a predicted image is generated based on a local decoded image obtained by encoding / decoding an input image, and difference data between the predicted image and the input image is encoded. As methods for generating a predicted image, methods called inter-screen prediction (inter prediction) and intra-screen prediction (intra prediction) are known.

  In addition, the decoded image or the image obtained by subjecting the decoded image to block noise reduction processing is subjected to filter processing using adaptively set filter coefficient groups, whereby the decoded image is reduced in noise. There is a technique called an adaptive loop filter (hereinafter also referred to simply as “adaptive filter”). The filter coefficient group used for the adaptive filter is adaptively determined so as to minimize the square error between the encoding target image and the filtered decoded image obtained by applying the adaptive filter to the decoded image. It is a thing.

  Also in the adaptive filter, the presence / absence of filter processing and the filter coefficient group are independently determined for the luminance component and the color difference component. Which color difference component is subjected to filtering is determined by a flag. When the filter for the color difference component is turned off, the filter process may be applied to both the color difference component Cb and the color difference component Cr when the filter process is applied to either the color difference component Cb or the color difference component Cr. When filter processing is applied to both the color difference component Cb and the color difference component Cr, the color difference component Cb and the color difference component Cr are processed by the same filter coefficient group.

  An encoding device and a decoding device including such an adaptive filter can improve prediction accuracy and encoding efficiency by generating a prediction image with reference to the filtered decoded image.

`` JCTVCA-A121 '', Joint Collaborative Team on Video Coding (JCT-VC) of ITU-T SG16 WP3 and ISO / IEC JTC1 / SC29 / WG11, 1st Mee-ting: Dresden, DE, 04/2010

  However, the same filter coefficient group is used for adaptive filter processing applied to the color difference component Cr and the color difference component Cb of the encoding target image. For this reason, the color difference component Cr and the color difference component Cb are not effectively filtered, and there is a problem that the encoding efficiency is not improved.

  The present invention has been made on the basis of the knowledge obtained by the inventor in view of the above-described problems, and an object thereof is to generate individual filter coefficient groups for the color difference component Cr and the color difference component Cb. Another object of the present invention is to realize an image filter device that can perform effective filter processing on each color difference component and improve encoding efficiency, and a decoding device and an encoding device including such an image filter device.

  In order to solve the above problem, the moving picture decoding apparatus according to the first configuration of the present invention is a moving picture decoding apparatus that decodes an image having a plurality of color components, and specifies a color component to be subjected to filter processing. And filter information decoding means for decoding the filter coefficient group, and information specifying the filter coefficient group and the color component decoded by the filter information decoding means, to filter each color component to be processed And filtering means for performing processing.

  Further, the filter information decoding means includes at least one filter coefficient of a filter coefficient group of a certain color component, a filter coefficient of a filter coefficient group of another color component that has already been decoded, and a value decoded from the encoded data. Decoding is performed using an addition value or a subtraction value.

  Further, the filter information decoding means decodes a filter coefficient group used for filter processing for a plurality of color components, and decodes without using filter coefficient groups of other color components that have already been decoded, and Decoding one or more dependent filter coefficient groups to be decoded using filter coefficient groups of other color components that have already been decoded, decoding an assignment flag indicating a color component to be filtered using an independent filter coefficient group, and The filter means performs filter processing using a filter coefficient group derived according to the allocation flag.

  The moving picture decoding apparatus according to the second configuration of the present invention is a moving picture decoding apparatus that decodes an input image having a plurality of color components, and includes a filter in each of a plurality of unit regions that constitute the input image. Filter information decoding means for decoding filter on / off information including one or more on / off flags that specify whether or not to perform processing, and a filter coefficient group, and color components for each unit region with reference to the filter on / off information And filtering means for performing the filtering process.

  The two or more colors may be determined by determining on / off of the unit region existing at the same position of two or more color components of the input image with reference to one on / off flag in the filter on / off information. The filter processing of components is controlled in common.

  Further, the filter information decoding means may select a selection flag for selecting whether the on / off flag included in the filter on / off information is used as an on / off flag for a specific color component or as a common on / off flag for a plurality of color components. It is characterized by decoding.

  The color component includes at least a luminance component and a color difference component, and the filter information decoding unit includes, as the selection flag, one filter on / off flag included in the filter on / off information as an on / off flag of the luminance component. It is characterized by decoding a flag that selects whether to use or as a common on / off flag for a luminance component and a color difference component.

  Further, the filter information decoding means outputs a control pattern 1 using an on / off flag only for a luminance component, a control pattern 2 using a common on / off flag for a luminance component and a color difference component, or a common on / off flag for a plurality of color difference components. When a selection mode indicating at least one of the control pattern 3 to be used or at least one of the control pattern 4 using an independent on / off flag with a luminance component and a plurality of color difference components is decoded, and the selection mode indicates the control pattern 1 or the control pattern 2 Decodes one on / off flag, decodes two on / off flags when the selection mode indicates control pattern 2, and decodes three on / off flags when the selection mode indicates control pattern 4 And

  In addition, the moving image encoding apparatus according to the first configuration of the present invention is an encoding apparatus that encodes an image having a plurality of color components, the information specifying the color component to be filtered, and the filter processing A filter information group for determining the filter information to be encoded as a filter parameter, and for each color component to be processed using the filter coefficient group determined by the filter information determination unit Filter means for performing filter processing and variable length encoding means for encoding filter information are provided.

  The filter information determining means determines at least one element of filter information based on a difference value between the determined filter coefficient of one filter coefficient group and the filter coefficient of another color component filter coefficient group. It is characterized by.

  In addition, the filter information determination means includes one independent filter coefficient group that is encoded without using filter coefficient groups of other color components, and a filter coefficient group that is encoded using filter coefficient groups of other color components. In addition, an allocation flag indicating a color component to be filtered is determined using an independent filter coefficient group, and the variable length encoding unit encodes the allocation flag.

  The moving image encoding apparatus according to the second configuration of the present invention is a moving image encoding apparatus that encodes an input image having a plurality of color components, and each of a plurality of unit regions that constitute the input image. The filter on / off information for specifying whether or not to perform the filter processing, the filter information determining means for determining the filter coefficient group used for the filter processing and the filter information to be encoded, and the filter on / off information and the filter coefficient group. Filter means for performing filter processing for each unit region, and variable length coding means for coding filter parameters including filter on / off information and filter information.

  The moving image encoding device is a moving image encoding device that encodes an image having two or more color components, and is configured to turn on and off the unit area existing at the same position of the two or more color components. Filter information determining means for determining a common on / off flag to be determined is provided.

  In addition, the filter information determination unit selects whether to use the already-encoded filter on / off information as an on / off flag for a specific color component or as an on / off flag common to a plurality of color components. It is characterized by determining.

  The color component includes at least a luminance component and a color difference component, and the filter information determination unit uses the already decoded filter on / off information as an on / off flag of the luminance component, or the luminance component and the color difference. A flag for selecting whether to use as a common on / off flag for components is determined.

  In addition, the filter information determination unit may output a control pattern 1 using an on / off flag only for the luminance component, a control pattern 2 using a common on / off flag for the luminance component and the color difference component, or a common on / off flag for a plurality of color difference components. When the selection mode indicating at least one of the control pattern 3 to be used or at least one of the control pattern 4 using the independent on / off flag with the luminance component and the plurality of color difference components is determined, and the selection mode indicates the control pattern 1 or the control pattern 2 Determines one on / off flag, determines two on / off flags when the selection mode indicates the control pattern 2, and determines three on / off flags when the selection mode indicates the control pattern 4. To do.

  Further, the data structure of the encoded data according to the first configuration of the present invention includes information specifying a color component to be subjected to filter processing, filter information decoding means for decoding a filter coefficient group, and decoding by the filter information decoding means. A plurality of filter means for performing a filtering process on each color component to be processed using the filter coefficient group and the information for designating the color component. The data structure of the encoded data used for the filtering process of the image having the color components includes information specifying the color components used by the filter means and a filter coefficient group.

  In addition, the data structure of the encoded data according to the second configuration of the present invention includes a filter including one or more on / off flags that specify whether or not to perform filter processing in each of a plurality of unit regions constituting the input image. A moving image comprising: filter information decoding means for decoding on / off information and a filter coefficient group; and filter means for performing color component filtering processing for each unit region with reference to the filter on / off information. A data structure of encoded data used for filter processing of an image having a plurality of color components referred to by a decoding device, comprising filter on / off information and a filter coefficient group used by the filter means And

  According to the moving picture decoding apparatus and the moving picture encoding apparatus of the present invention, different filter coefficient groups can be used for an image having a plurality of color difference components. Compared to the above, the image quality of the color difference component can be improved. Further, by encoding the filter coefficient group of at least one color difference component as a difference value of the filter coefficient group of other color difference components, the code amount of the filter coefficient group can be reduced.

It is a figure which shows the data structure of the encoding data produced | generated by the moving image encoder which concerns on 1st Embodiment, and is referred by the moving image decoder which concerns on embodiment of this invention. (A) shows the configuration of the picture layer of the encoded data, (b) shows the configuration of the slice layer included in the picture layer, and (c) shows the LCU layer included in the slice layer. (D) shows the configuration of the leaf CU included in the CU layer, (e) shows the configuration of the inter prediction information for the leaf CU, ( f) shows the configuration of the intra prediction information for the leaf CU, and (g) shows the configuration of the filter parameter included in the slice header. It is a figure which shows the data structure of the colour-difference filter information contained in the coding data produced | generated by the moving image encoder which concerns on 1st Embodiment, and is referred by the moving image decoder which concerns on embodiment of this invention. (A)-(e) has shown the structure of the color difference filter information when color difference filter mode alf_chroma_idc is 0-4. (I) of (e) shows the configuration of the color difference filter information when the first color difference component is designated in advance when the color difference filter mode alf_chroma_idc is 4. (Ii) shows the configuration of the color difference filter information when the first color difference component is specified by sw_flag when the color difference filter mode alf_chroma_idc is 4. It is a figure which shows each syntax contained in the color difference filter information of the coding data which concerns on 1st Embodiment, and when the color difference filter mode alf_chroma_idc is 4, it is a case where the 1st color difference component is designated beforehand. It is a block diagram which shows the structure of the moving image decoding apparatus which concerns on 1st Embodiment. It is a block diagram which shows the structure of the adaptive filter with which the moving image decoding apparatus which concerns on 1st Embodiment is provided. It is a figure for demonstrating the color difference adaptive filter coefficient deriving part with which the adaptive filter which concerns on 1st Embodiment is equipped, Comprising: (a) is a filter contained in filter coefficient information when color difference filter mode alf_chroma_idc is 1 and 2 It is a block diagram which derives filter coefficient group HCr and filter coefficient group HCb from coefficient group coeff_Cb and filter coefficient group coeff_Cr. (B) is a block diagram for deriving the filter coefficient group HCr and the filter coefficient group HCb from the filter coefficient group coeff_chroma included in the filter coefficient information when the color difference filter mode alf_chroma_idc is 3. It is a figure for demonstrating the color difference adaptive filter coefficient derivation | leading-out part with which the adaptive filter which concerns on 1st Embodiment is equipped, Comprising: (a) is 1st color difference component beforehand color difference component Cr when color difference filter mode alf_chroma_idc is 4. FIG. 6 is a block diagram of a color difference adaptive filter coefficient derivation unit when designated by (B) is a block diagram of the color difference adaptive filter coefficient derivation unit when the first color difference component is designated in advance as the color difference component Cb when the color difference filter mode alf_chroma_idc is 4. It is a figure for demonstrating the color difference adaptive filter coefficient deriving part with which the adaptive filter which concerns on 1st Embodiment is provided, Comprising: When the color difference filter mode alf_chroma_idc is 4, the 1st color difference component C1 is designated by the allocation flag sw_flag FIG. 3 is a block diagram of a color difference adaptive filter coefficient deriving unit in FIG. It is a figure for demonstrating the switch part with which the color difference adaptive filter part which concerns on 1st Embodiment is provided, Comprising: It is a table | surface which shows on / off of the switch designated by color difference filter mode alf_chroma_idc. It is a figure for demonstrating the filter process by the adaptive filter which concerns on 1st Embodiment, Comprising: (a) is referred in order to calculate the pixel value of the filter object pixel in the object unit area | region UR and the object unit area | region UR. FIG. 7 is a diagram illustrating a filter reference region R that is a set of pixels to be filtered and a filter reference range RA defined as a union of the filter reference regions R for each filter target pixel. It is a figure which shows the filter coefficient allocated to each pixel contained in. It is a block diagram which shows the structure of the moving image encoder which concerns on 1st Embodiment. It is a block diagram which shows the structure of the adaptive filter with which the moving image encoder which concerns on 1st Embodiment is provided. It is a block diagram which shows the structure of the color difference filter information determination part with which the adaptive filter which concerns on 1st Embodiment is provided. It is a figure which shows the data structure of the filter on / off information of the coding data which concerns on 2nd Embodiment. (A)-(d) has shown the structure of the filter on-off information at the time of the control pattern 1-the control pattern 4. FIG. It is a figure which shows each syntax contained in the filter parameter of the control pattern 1 of the coding data which concerns on 2nd Embodiment. It is a figure which shows each syntax contained in the filter parameter of the control pattern 2 of the coding data which concerns on 2nd Embodiment. It is a figure which shows each syntax contained in the filter parameter of the control pattern 3 of the coding data which concerns on 2nd Embodiment. It is a figure which shows each syntax contained in the filter parameter of the control pattern 4 of the coding data which concerns on 2nd Embodiment. It is a block diagram which shows the structure of the moving image decoding apparatus which concerns on 2nd Embodiment. It is a block diagram which shows the structure of the adaptive filter with which the moving image decoding apparatus which concerns on 2nd Embodiment is provided. It is a table | surface which shows the correspondence of ON / OFF flag AlfFilterFlagY, AlfFilterFlagCr, AlfFilterFlagCb used for ON / OFF control, and ON / OFF flag alf_cu_flag, alf_cu_flag_luma, alf_cu_flag_chroma, alf_cu_flag_cr, alf_cu_flag_cb of the encoded data which concern on 2nd Embodiment. It is a block diagram which shows the structure of the moving image encoder which concerns on 2nd Embodiment. It is a block diagram which shows the structure of the adaptive filter with which the moving image encoder which concerns on 2nd Embodiment is provided. It is a block diagram which shows the structure of the filter parameter determination part with which the adaptive filter which concerns on 2nd Embodiment is provided. It is a figure which shows each syntax contained in the color difference filter information of the coding data which concerns on 1st Embodiment, and when the color difference filter mode alf_chroma_idc is 4, it is a case where the allocation flag sw_flag is designated for the 1st color difference component. It is a figure for demonstrating the adaptive filter process when applying the on-off flag of the area unit which concerns on 2nd Embodiment, (a) is each encoding used as the object of on-off control in a largest encoding unit. It is a figure which shows the example of a division | segmentation with the branch diagram showing a hierarchical structure, (b) is a figure which shows on / off of the object area designated by the on / off flag. It is a figure which shows each syntax contained in the filter parameter which concerns on 2nd Embodiment, and is a case where the structure of the filter on / off information of the control pattern 1-control pattern 4 is switched by the selection flag alf_cu_control_mode. It is a figure which shows each syntax contained in the filter parameter which concerns on 2nd Embodiment, and is a case where the structure of the filter on / off information of the control pattern 1 and the control pattern 3 is switched by the selection flag alf_cu_control_mode. It is a figure which shows each syntax contained in the color difference filter information of the coding data which concerns on 1st Embodiment, and it replaces with the syntax alf_chroma_idc of FIG. 3, and applies 1st filter mode alf_chroma_idc1 and 2nd filter mode alf_chroma_idc2. Is the case. It is a figure explaining 1st filter mode alf_chroma_idc1 and 2nd filter mode alf_chroma_idc2 which concern on 1st Embodiment, Comprising: (a) is filter processing of color difference component Cr and color difference component Cb designated by 1st filter mode alf_chroma_idc1 (B) is a figure which shows the filter coefficient group of the filter process of the color difference component Cr designated by 2nd filter mode alf_chroma_idc2, and the color difference component Cb.

[Embodiment 1]
Below, the 1st Embodiment of this invention is described with reference to FIGS. 1-13 and FIG. Note that the decoding apparatus according to the present embodiment decodes a moving image from encoded data. Therefore, hereinafter, this is referred to as “moving image decoding apparatus”. In addition, the encoding device according to the present embodiment generates encoded data by encoding a moving image. Therefore, in the following, this is referred to as a “video encoding device”.

However, the scope of application of the first embodiment of the present invention is not limited to this. That is, as will be apparent from the following description, the features of the present invention can be realized without assuming a plurality of frames. That is, the present invention can be applied to a general decoding apparatus and a general encoding apparatus regardless of whether the target is a moving image or a still image.
(Configuration of encoded data # 1)

  Prior to the description of the video decoding device 1 according to the present embodiment, the configuration of the encoded data # 1 generated by the video encoding device 2 according to the present embodiment and decoded by the video decoding device 1 will be described with reference to FIG. Will be described with reference to FIG. The encoded data # 1 has a hierarchical structure including a sequence layer, a GOP (Group Of Pictures) layer, a picture layer, a slice layer, and a maximum coding unit (LCU) layer.

  The hierarchical structure below the picture layer in the encoded data # 1 is shown in FIG. FIGS. 1A to 1F are a picture layer P, a slice layer S, an LCU layer LCU, a leaf CU included in the LCU (denoted as CUL in FIG. 1D), and inter prediction (inter-screen prediction), respectively. It is a figure which shows the structure of inter prediction information PI_Inter which is the prediction information PI about a partition, and intra prediction information PI_Intra which is the prediction information PI about an intra prediction (prediction in a screen) partition.

(Picture layer)
The picture layer P is a set of data that is referenced by the video decoding device 1 in order to decode a target picture that is a processing target picture. As shown in FIG. 1A, the picture layer P includes a picture header PH and slice layers S1 to SNs (Ns is the total number of slice layers included in the picture layer P).

  The picture header PH includes a coding parameter group that is referred to by the video decoding device 1 in order to determine a decoding method of the target picture. For example, the encoding mode information (entropy_coding_mode_flag) indicating the variable length encoding mode used in encoding by the moving image encoding device 2 is an example of an encoding parameter included in the picture header PH.

(Slice layer)
Each slice layer S included in the picture layer P is a set of data referred to by the video decoding device 1 in order to decode a target slice that is a slice to be processed. As shown in FIG. 1B, the slice layer S includes a slice header SH and LCU layers LCU1 to LUNc (Nc is the total number of LCUs included in the slice S).

  The slice header SH includes an encoding parameter group that is referred to by the video decoding device 1 in order to determine a decoding method of the target slice. Slice type designation information (slice_type) for designating a slice type is an example of an encoding parameter included in the slice header SH.

  As slice types that can be specified by the slice type specification information, (1) I slice that uses only intra prediction at the time of encoding, (2) P slice that uses unidirectional prediction or intra prediction at the time of encoding, (3) B-slice using unidirectional prediction, bidirectional prediction, or intra prediction at the time of encoding may be used.

  The slice header SH includes a filter parameter FP that is referred to by an adaptive filter provided in the video decoding device 1. The configuration of the filter parameter FP will be described later and will not be described here.

(LCU layer)
Each LCU layer LCU included in the slice layer S is a set of data that the video decoding device 1 refers to in order to decode the target LCU that is the processing target LCU.

  The LCU layer LCU is configured by a plurality of coding units (CU: Coding Units) obtained by hierarchically dividing the LCU into a quadtree. In other words, the LCU layer LCU is a coding unit corresponding to the highest level in a hierarchical structure that recursively includes a plurality of CUs. As shown in FIG. 1C, each CU included in the LCU layer LCU has a hierarchical structure that recursively includes a CU header CUH and a plurality of CUs obtained by dividing the CU into quadtrees. doing.

  The size of each CU excluding the LCU is half the size of the CU to which the CU directly belongs (that is, the CU one layer higher than the CU), and the size that each CU can take is encoded data # 1. Depending on the size and hierarchical depth of the LCU included in the sequence parameter set SPS. For example, when the size of the LCU is 128 × 128 pixels and the maximum hierarchical depth is 5, the CUs in the hierarchical level below the LCU have five sizes, that is, 128 × 128 pixels and 64 × 64 pixels. , 32 × 32 pixels, 16 × 16 pixels, and 8 × 8 pixels. A CU that is not further divided is called a leaf CU.

(CU header)
The CU header CUH includes a coding parameter referred to by the video decoding device 1 in order to determine a decoding method of the target CU. Specifically, as shown in FIG. 1C, a CU division flag SP_CU for specifying whether or not the target CU is further divided into four subordinate CUs is included. When the CU division flag SP_CU is 0, that is, when the CU is not further divided, the CU is a leaf CU.

(Leaf CU)
A CU (CU leaf) that is not further divided is handled as a prediction unit (PU: Prediction Unit) and a transform unit (TU: Transform Unit).

  As shown in FIG. 1 (d), the leaf CU (denoted as CUL in FIG. 1 (d)) includes (1) PU information PUI that is referred to when the moving image decoding apparatus 1 generates a predicted image, and (2) The TU information TUI that is referred to when the residual data is decoded by the moving picture decoding apparatus 1 is included.

  The skip flag SKIP is a flag indicating whether or not the skip mode is applied to the target PU. When the value of the skip flag SKIP is 1, that is, when the skip mode is applied to the target leaf, PU information PUI and TU information TUI in the leaf CU are omitted. Note that the skip flag SKIP is omitted for the I slice.

  As shown in FIG. 1D, the PU information PUI includes a skip flag SKIP, prediction type information PT, and prediction information PI. The prediction type information PT is information that specifies whether intra prediction or inter prediction is used as a predicted image generation method for the target leaf CU (target PU). The prediction information PI includes intra prediction information PI_Intra or inter prediction information PI_Inter depending on which prediction method is specified by the prediction type information PT. Hereinafter, a PU to which intra prediction is applied is also referred to as an intra PU, and a PU to which inter prediction is applied is also referred to as an inter PU.

  The PU information PUI includes information designating the shape and size of each partition included in the target PU and the position in the target PU. Here, the partition is one or a plurality of non-overlapping areas constituting the target leaf CU, and the generation of the predicted image is performed in units of partitions.

  As shown in FIG. 1D, the TU information TUI specifies a quantization parameter difference Δqp (tu_qp_delta) that specifies the magnitude of the quantization step, and a division pattern for each block of the target leaf CU (target TU). It includes TU partition information SP_TU and quantized prediction residuals QD1 to QDNT (NT is the total number of blocks included in the target TU).

  The quantization parameter difference Δqp is a difference qp−qp ′ between the quantization parameter qp in the target TU and the quantization parameter qp ′ in the TU encoded immediately before the TU.

  Specifically, the TU partition information SP_TU is information that specifies the shape and size of each block included in the target TU, and the position in the target TU. Each TU can be, for example, a size from 64 × 64 pixels to 2 × 2 pixels. Here, the block is one or a plurality of non-overlapping areas constituting the target leaf CU, and encoding / decoding of the prediction residual is performed in units of blocks.

Each quantized prediction residual QD is encoded data generated by the video encoding device 2 performing the following processes 1 to 3 on a target block that is a processing target block. Process 1: DCT transform (Discrete Cosine Transform) is performed on the prediction residual obtained by subtracting the prediction image from the encoding target image. Process 2: The DCT coefficient obtained in Process 1 is quantized. Process 3: The DCT coefficient quantized in Process 2 is variable length encoded. The quantization parameter qp described above represents the magnitude of the quantization step QP used when the moving picture coding apparatus 2 quantizes the DCT coefficient (QP = 2 ^{qp / 6} ).

(Inter prediction information PI_Inter)
The inter prediction information PI_Inter includes a coding parameter that is referred to when the video decoding device 1 generates an inter prediction image by inter prediction. As shown in FIG. 1 (e), the inter prediction information PI_Inter includes inter PU partition information SP_Inter that specifies a partition pattern of the target PU into each partition, and inter prediction parameters PP_Inter1 to PP_InterNe (Ne for each partition). The total number of inter prediction partitions included in the target PU).

Specifically, the inter-PU partition information SP_Inter is information that specifies the shape and size of each inter prediction partition included in the target PU (inter PU) and the position in the target PU.

  The inter PU is composed of 4 symmetric splittings of 2N × 2N pixels, 2N × N pixels, N × 2N pixels, and N × N pixels, and 2N × nU pixels, 2N × nD pixels, nL × 2N With a pixel and four asymmetric splittings of nR × 2N pixels, it can be divided into a total of 8 partitions. Here, the specific value of N is defined by the size of the CU to which the PU belongs, and the specific values of nU, nD, nL, and nR are determined according to the value of N. For example, an inter PU of 128 × 128 pixels is 128 × 128 pixels, 128 × 64 pixels, 64 × 128 pixels, 64 × 64 pixels, 128 × 32 pixels, 128 × 96 pixels, 32 × 128 pixels, and 96 × It is possible to divide into 128-pixel inter prediction partitions.

(Inter prediction parameter PP_Inter)
As illustrated in FIG. 1E, the inter prediction parameter PP_Inter includes a reference image index RI, an estimated motion vector index PMVI, and a motion vector residual MVD.

  The motion vector residual MVD is encoded data generated by the moving image encoding device 2 executing the following processes 4 to 6. Process 4: Select an encoded / decoded locally decoded image (more precisely, an image obtained by performing deblocking processing and adaptive filtering on the encoded / decoded local decoded image) The motion vector mv for the target partition is derived with reference to the selected encoded / decoded local decoded image (hereinafter also referred to as “reference image”). Process 5: An estimation method is selected, and an estimated value (hereinafter also referred to as “estimated motion vector”) pmv of the motion vector mv assigned to the target partition is derived using the selected estimation method. Process 6: The motion vector residual MVD obtained by subtracting the estimated motion vector pmv derived in Process 5 from the motion vector mv derived in Process 4 is encoded.

  The reference image index RI designates the locally decoded image (reference image) that has been encoded / decoded selected in the process 4. The estimated motion vector index PMVI described above is the estimation method selected in the process 5. Is specified. The estimation methods that can be selected in the processing 5 include: (1) a locally decoded image being encoded / decoded (more precisely, a region that has already been decoded in a locally decoded image being encoded / decoded). In an image obtained by performing block processing and adaptive filter processing), a median of a motion vector allocated to a partition adjacent to the target partition (hereinafter also referred to as “adjacent partition”) is used as an estimated motion vector pmv. (2) In a locally decoded image that has been encoded / decoded, a motion vector assigned to a partition (often referred to as a “collocated partition”) occupying the same position as the target partition is used as an estimated motion vector pmv, etc. Is mentioned.

  In addition, as shown in FIG. 1E, the prediction parameter PP related to the partition for which unidirectional prediction is performed includes one reference image index RI, estimated motion vector index PMVI, and one motion vector residual MVD. However, the prediction parameters PP related to the partition performing bi-directional prediction (weighted prediction) include two reference image indexes RI1 and RI2, two estimated motion vector indexes PMVI1 and PMVI2, and two motion vector residuals MVD1. And MVD2.

(Intra prediction information PI_Intra)
The intra prediction information PI_Intra includes an encoding parameter that is referred to when the video decoding device 1 generates an intra predicted image by intra prediction. As shown in FIG. 1 (f), the intra prediction information PI_Intra includes intra PU partition information SP_Intra that specifies a partition pattern of the target PU (intra PU) into each partition, and intra prediction parameters PP_Intra1 to PP_IntraNa for each partition. (Na is the total number of intra prediction partitions included in the target PU).

Specifically, the intra-PU partition information SP_Intra is information that specifies the shape and size of each intra-predicted partition included in the target PU, and the position in the target PU. The intra PU split information SP_Intra includes an intra split flag (intra_split_flag) that specifies whether or not the target PU is split into partitions. If the intra partition flag is 1, the target PU is divided symmetrically into four partitions. If the intra partition flag is 0, the target PU is not divided and the target PU itself is one partition. Are treated as Therefore, if the size of the target PU is 2N × 2N pixels, the intra prediction partition can take any of 2N × 2N pixels (no division) and N × N pixels (four divisions) (where, N = 2 ⁿ , n is an arbitrary integer of 1 or more). For example, a 128 × 128 pixel intra PU can be divided into 128 × 128 pixel and 64 × 64 pixel intra prediction partitions.

(Intra prediction parameter PP_Intra)
The intra prediction parameter PP_Intra includes an estimation flag MPM and a residual prediction mode index RIPM as shown in FIG. The intra prediction parameter PP_Intra is a parameter for designating an intra prediction method (prediction mode) for each partition.

  The estimation flag MPM is a flag indicating whether or not the prediction mode estimated based on the prediction mode allocated to the peripheral partition of the target partition that is the processing target is the same as the prediction mode for the target partition. . Here, examples of partitions around the target partition include a partition adjacent to the upper side of the target partition and a partition adjacent to the left side of the target partition.

  The residual prediction mode index RIPM is an index included in the intra prediction parameter PP_Intra when the estimated prediction mode and the prediction mode for the target partition are different, and is an index for designating a prediction mode assigned to the target partition. It is.

(Filter parameter FP)
As described above, the slice header SH includes the filter parameter FP that is referred to by the adaptive filter included in the video decoding device 1. FIG. 1G shows the data structure of the filter parameter FP. As shown in FIG. 1G, the filter parameter FP includes filter on / off information, luminance filter information, and color difference filter information.

  The filter on / off information includes (1) area designation information for designating a divided area included in the target slice, and (2) on / off information for designating on / off of the filter process for each divided area.

The luminance filter information includes luminance filter coefficient information, and the chrominance filter information includes chrominance filter mode alf_chroma_idc and chrominance filter coefficient information for switching whether or not to perform filter processing on the chrominance component. The color difference filter coefficient information includes the number of color difference component taps alf_length_chroma_minus5_div2 and a color difference filter coefficient group. The filter coefficient group includes (1) filter coefficients a _{0 to} a _NT-1 (NT is the total number of filter coefficients included in the filter coefficient group), and (2) offset o.

  FIG. 2 shows a data structure of color difference filter coefficient information for each alf_chroma_idc. When alf_chroma_idc is 0, the color difference filter coefficient information is omitted as shown in FIG. When alf_chroma_idc is 1, as shown in FIG. 2B, the color difference filter coefficient information includes alf_length_chroma_minus5_div2 and a filter coefficient group alf_coeff_Cr of the color difference component Cr. When alf_chroma_idc is 2, as shown in FIG. 2C, the color difference filter coefficient information includes alf_length_chroma_minus5_div2 and a filter coefficient group alf_coeff_Cb of the color difference component Cb. When alf_chroma_idc is 3, as shown in FIG. 2D, the chrominance filter coefficient information includes alf_length_chroma_minus5_div2 and a filter coefficient group alf_coeff_chroma. When alf_chroma_idc is 4, as shown in (i) of FIG. 2E, the chrominance filter coefficient information includes alf_chroma_idc, an independent filter coefficient group alf_coeff_C1 and a dependent filter coefficient group alf_coeff_C2 for the chrominance component. Here, one of the two color difference components is expressed as a first color difference component C1, and the other is expressed as a second color difference component C2. The filter coefficient group coeff_C1 is a filter coefficient group for deriving the color difference component C1, and the filter coefficient group alf_coeff_C2 is a difference filter coefficient group for deriving the color difference component C2. Further, hereinafter, when the value of alf_chroma_idc is a mode number and alf_chroma_idc is 0, 1, 2, 3, 4, they are also called mode 0, mode 1, mode 2, mode 3, and mode 4, respectively.

  (Ii) of FIG. 2 (e) shows a configuration including a flag sw_flag for designating a color difference component corresponding to the first color difference component C1, as another configuration when alf_chroma_idc is 4.

  FIG. 3 is a syntax included in the color difference filter information of the encoded data # 1 according to the present embodiment. As shown in FIG. 3, the color difference filter information of the encoded data # 1 according to the present embodiment includes (1) syntax (color difference filter mode) alf_chroma_idc that specifies whether or not to perform filter processing on each color difference component , (2) syntax alf_length_chroma_minus5_div2 for specifying the filter length of the color difference adaptive filter, and (3) syntax for specifying the filter coefficient group. The syntax for specifying the filter coefficient group is alf_coeff_Cr [i] when alf_chroma_idc is 1, alf_coeff_Cb [i] when alf_chroma_idc is 2, alf_coeff_chroma [i] when alf_chroma_idc is 3, and alf_chroma_idc is 4. alf_coeff_C1 [i] and alf_coeff_C2 are included. FIG. 25 shows a syntax including a flag sw_flag. In this configuration, when alf_chroma_idc is 4, sw_flag is included.

  Below, the moving image decoding apparatus 1 which concerns on this embodiment is demonstrated with reference to FIGS. The moving picture decoding apparatus 1 includes H.264 as a part thereof. H.264 / MPEG-4. The decoding apparatus includes a technique adopted in a test model HM of AVC, VCEG (Video Coding Expert Group), and HEVC (High Efficiency Video Coding) proposed as a successor codec.

  FIG. 4 is a block diagram showing a configuration of the moving picture decoding apparatus 1. As shown in FIG. 4, the moving image decoding apparatus 1 includes a variable length code decoding unit 11, a motion vector restoration unit 12, an inverse quantization / inverse conversion unit 13, an adder 14, a buffer memory 15, and an inter prediction image generation unit 16. , An intra prediction image generation unit 17, a prediction method determination unit 18, a deblocking filter 19, and an adaptive filter 30. The moving picture decoding apparatus 1 is an apparatus for generating moving picture # 2 by decoding encoded data # 1.

(Variable-length code decoding unit 11)
The variable length code decoding unit 11 decodes the prediction parameter PP for each partition from the encoded data # 1. That is, for the inter prediction partition, the reference image index RI, the estimated motion vector index PMVI, and the motion vector residual MVD are decoded from the encoded data # 1, and these are supplied to the motion vector restoration unit 12. On the other hand, with respect to the intra prediction partition, (1) size designation information for designating the partition size and (2) prediction index designation information for designating the prediction index are decoded from the encoded data # 1, and this is decoded into the intra prediction image. This is supplied to the generation unit 17. Furthermore, the variable-length code decoding unit 11 decodes the quantization prediction residual QD for each block and the quantization parameter difference Δqp for the macroblock including the block from the encoded data # 1, and dequantizes them. This is supplied to the inverse conversion unit 13. In addition, the variable length code decoding unit 11 decodes the filter parameter FP from the encoded data # 1 and supplies it to the adaptive filter 30.

(Motion vector restoration unit 12)
The motion vector restoration unit 12 restores the motion vector mv related to each inter prediction partition from the motion vector residual MVD related to that partition and the restored motion vector mv ′ related to another partition. Specifically, (1) the estimated motion vector pmv is derived from the restored motion vector mv ′ according to the estimation method specified by the estimated motion vector index PMVI, and (2) the derived estimated motion vector pmv and the motion vector remaining are derived. The motion vector mv is obtained by adding the difference MVD. It should be noted that the restored motion vector mv ′ relating to other partitions can be read from the buffer memory 15. The motion vector restoration unit 12 supplies the restored motion vector mv together with the corresponding reference image index RI to the inter predicted image generation unit 16.

(Inter prediction image generation unit 16)
The inter prediction image production | generation part 16 produces | generates the motion compensation image mc regarding each inter prediction partition by inter prediction. Specifically, using the motion vector mv supplied from the motion vector restoration unit 12, the motion compensated image mc from the filtered decoded image P_FL ′ designated by the reference image index RI also supplied from the motion vector restoration unit 12 is used. Is generated. Here, the filtered decoded image P_FL ′ is an image obtained by performing the deblocking process by the deblocking filter 19 and the filtering process by the adaptive filter 30 on the decoded image that has already been decoded for the entire frame. The inter-predicted image generation unit 16 can read out the pixel value of each pixel constituting the filtered decoded image P_FL ′ from the buffer memory 15. The motion compensation image mc generated by the inter prediction image generation unit 16 is supplied to the prediction method determination unit 18 as an inter prediction image Pred_Inter.

(Intra predicted image generation unit 17)
The intra predicted image generation unit 17 generates a predicted image Pred_Intra related to each intra prediction partition. Specifically, first, a prediction mode is specified based on the intra prediction parameter PP_Intra supplied from the variable length code decoding unit 11, and the specified prediction mode is assigned to the target partition in, for example, raster scan order.

  Here, the prediction mode based on the intra prediction parameter PP_Intra can be specified as follows. (1) The estimation flag MPM is decoded, and the estimation flag MPM indicates that the prediction mode for the target partition to be processed is the same as the prediction mode assigned to the peripheral partition of the target partition. If it is, the prediction mode assigned to the partition around the target partition is assigned to the target partition. (2) On the other hand, if the estimation flag MPM indicates that the prediction mode for the target partition to be processed is not the same as the prediction mode assigned to a partition around the target partition, the remaining The prediction mode index RIPM is decoded, and the prediction mode indicated by the residual prediction mode index RIPM is assigned to the target partition.

  The intra predicted image generation unit 17 generates a predicted image Pred_Intra from the (local) decoded image P by intra prediction according to the prediction method indicated by the prediction mode assigned to the target partition. The intra predicted image Pred_Intra generated by the intra predicted image generation unit 17 is supplied to the prediction method determination unit 18. Note that the intra predicted image generation unit 17 may be configured to generate a predicted image Pred_Intra from the filtered decoded image P_FL by intra prediction.

(Prediction method determination unit 18)
The prediction method determination unit 18 determines whether each partition is an inter prediction partition that should perform inter prediction or an intra prediction partition that should perform intra prediction, based on the prediction type information PT for the PU to which each partition belongs. To do. In the former case, the inter prediction image Pred_Inter generated by the inter prediction image generation unit 16 is supplied to the adder 14 as the prediction image Pred. In the latter case, the intra prediction image generation unit 17 generates the inter prediction image Pred_Inter. The intra predicted image Pred_Intra that has been processed is supplied to the adder 14 as the predicted image Pred.

(Inverse quantization / inverse transform unit 13)
The inverse quantization / inverse transform unit 13 (1) inversely quantizes the quantized prediction residual QD, (2) performs inverse DCT (Discrete Cosine Transform) transform on the DCT coefficient obtained by the inverse quantization, and (3) The prediction residual D obtained by the inverse DCT transform is supplied to the adder 14. When the quantization prediction residual QD is inversely quantized, the inverse quantization / inverse transform unit 13 derives the quantization step QP from the quantization parameter difference Δqp supplied from the variable length code decoding unit 11. The quantization parameter qp can be derived by adding the quantization parameter difference Δqp to the quantization parameter qp ′ relating to the TU that has been inversely quantized / inversely DCT transformed immediately before, and the quantization step QP is derived from the quantization step qp, for example, QP = 2 ^{pq / 6} . The generation of the prediction residual D by the inverse quantization / inverse transform unit 13 is performed in units of blocks obtained by dividing TUs or TUs.

(Adder 14)
The adder 14 generates the decoded image P by adding the prediction image Pred supplied from the prediction method determination unit 18 and the prediction residual D supplied from the inverse quantization / inverse conversion unit 13. The generated decoded image P is stored in the buffer memory 15.

(Deblocking filter 19)
When the difference between the pixel values of pixels adjacent to each other via a block boundary or partition boundary in the decoded image P is smaller than a predetermined threshold, the deblocking filter 19 By performing a deblocking process on the partition boundary, the block boundary or an image near the partition boundary is smoothed. The image subjected to the deblocking process by the deblocking filter 19 is output to the adaptive filter 30 as a deblocked decoded image P_DB.

(Adaptive filter 30)
The adaptive filter 30 performs adaptive filter processing on the luminance component Y, the color difference component Cr, and the color difference component Cb on the deblocked decoded image P_DB to generate a filtered decoded image P_FL.

  FIG. 5 is a block diagram of the adaptive filter 30. As shown in FIG. 5, the adaptive filter 30 includes a color difference adaptive filter information decoding unit 31, a color difference adaptive filter unit 32, and a luminance adaptive filter unit 33.

(Color difference adaptive filter information decoding unit 31)
The color difference adaptive filter information decoding unit 31 decodes alf_chroma_idc from the filter parameter FP, and further decodes the number of taps, the filter coefficient group HCr, and the filter coefficient group HCb according to the value of alf_chroma_idc. Here, the filter coefficient group HCr and the filter coefficient group HCb are filter coefficient groups for adaptive filter processing applied to the color difference component Cr and the color difference component Cb.

  As shown in FIG. 5, the color difference adaptive filter information decoding unit 31 includes a color difference adaptive filter coefficient deriving unit 311. The filter coefficient group HCb and the filter coefficient group HCr derived by the color difference adaptive filter coefficient deriving unit 311 are supplied to the color difference adaptive filter unit 32.

(Color difference adaptive filter coefficient deriving unit 311)
The color difference adaptive filter coefficient deriving unit 311 will be described with reference to FIGS. The operation of the color difference adaptive filter coefficient deriving unit 311 is switched by alf_chroma_idc. The color difference adaptive filter coefficient deriving unit 311 derives the filter tap number tap_chroma and the filter coefficient number AlfNumCoeffChroma from alf_length_chroma_minus5_div2 by the following equation.
tap_chroma = (alf_length_chroma_minus5_div2 << 1) +5
AlfNumCoeffChroma = ((tap_chroma * tap_chroma + 1) >> 1) +1

  When alf_chroma_idc = 0, the filter coefficient group HCr and the filter coefficient group HCb are not derived.

When alf_chroma_idc = 1, only the filter coefficient group HCr is derived, and the filter coefficient group HCb is not derived. The filter coefficient group alf_coeff_Cr decoded from the filter parameter FP is assigned to the filter coefficient group HCr by the following expression.
HCr [i] = alf_coeff_Cr [i]
Here, i is an integer from 0 to AlfNumCoeffChroma-1.

When alf_chroma_idc = 2, only the filter coefficient group HCb is derived, and the filter coefficient group HCr is not derived. The filter coefficient group alf_coeff_Cb decoded from the filter parameter FP is assigned to the filter coefficient group HCb by the following expression.
HCb [i] = alf_coeff_Cb [i]
Here, i is an integer from 0 to AlfNumCoeffChroma-1.

When alf_chroma_idc = 3, the filter coefficient group HCr and the filter coefficient group HCb are derived. The filter coefficient group alf_coeff_chroma decoded from the filter parameter FP is assigned to the filter coefficient group HCr and the filter coefficient group HCb according to the following expression.
HCr [i] = alf_coeff_chroma [i]
HCb [i] = alf_coeff_chroma [i]
Here, i is an integer from 0 to AlfNumCoeffChroma-1.

When alf_chroma_idc = 4, the filter coefficient prediction processing unit 3111 included in the color difference adaptive filter coefficient deriving unit 311 performs the second color difference component by subtraction for each element of the independent filter coefficient group alf_coeff_C1 [i] and the dependent filter coefficient group alf_coeff_C2 [i]. A filter coefficient group HC2 for C2 is derived.
HC1 [i] = alf_coeff_C1 [i]
HC2 [i] = alf_coeff_C1 [i] −alf_coeff_C2 [i]
Here, i is an integer from 0 to AlfNumCoeffChroma-1.
The derived filter coefficient group HC1 and filter coefficient group HC2 are assigned to the filter coefficient group HCr and the filter coefficient group HCb according to the correspondence relationship between the first color difference component C1 and the second color difference component C2.

In this case, in the moving picture encoding apparatus 2 described later, a difference value between the filter coefficient HC2 [i] of the filter coefficient group of the second chrominance component C2 and the filter coefficient HC1 [i] of the filter coefficient group of the first chrominance component C1. Dependent filter coefficient group alf_coeff_C2 [i] is defined by the following equation.
alf_coeff_C2 [i] = HC1 [i] −HC2 [i]
Here, i is an integer from 0 to AlfNumCoeffChroma-1.

Note that the filter coefficient prediction processing unit 3111 may derive the filter coefficient group HC2 of the second color difference component C2 by addition of each element of the independent filter coefficient group alf_coeff_C1 [i] and the dependent filter coefficient group alf_coeff_C2 [i]. .
HC2 [i] = alf_coeff_C1 [i] + alf_coeff_C2 [i]
Here, i is an integer from 0 to AlfNumCoeffChroma-1.

In this case, the moving picture coding apparatus 2 to be described later calculates a difference value between the two filter coefficient groups by the following formula to determine a dependent filter coefficient group alf_coeff_C2 [i].
alf_coeff_C2 [i] = HC2 [i] −HC1 [i]
Here, i is an integer from 0 to AlfNumCoeffChroma-1.

In the case where the first color difference component is determined in advance, as shown in FIG. 7A, the filter coefficient group HCr and the filter coefficient group HCb are assigned by the following equations.
HCr [i] = HC1 [i]
HCb [i] = HC2 [i]
Here, i is an integer from 0 to AlfNumCoeffChroma-1.

As shown in FIG. 7B, the first color difference component C1 may be the color difference component Cb. In this case, the filter coefficient group HCr and the filter coefficient group HCb are assigned by the following equations.
HCb [i] = HC1 [i]
HCr [i] = HC2 [i]
Here, i is an integer from 0 to AlfNumCoeffChroma-1.

  When the first color difference component C1 is determined by sw_flag, the filter coefficient group HC1 and the filter coefficient group HC2 are allocated by the color difference filter coefficient allocation unit 3112 as shown in FIG.

  The color difference filter coefficient assigning unit 3112 assigns the filter coefficient group HC1 and the filter coefficient group HC2 according to sw_flag. When sw_flag is 0, the filter coefficient group HC1 is assigned to the filter coefficient group HCr, and the filter coefficient group HC2 is assigned to the filter coefficient group HCb. When sw_flag is 1, the filter coefficient group HC1 is assigned to the filter coefficient group HCb, and the filter coefficient group HC2 is assigned to the filter coefficient group HCr.

(Color difference adaptive filter unit 32)
The color difference adaptive filter unit 32 performs adaptive filter processing on the color difference component Cr and the color difference component Cb of the deblocked decoded image P_DB to generate the color difference component Cr and the color difference component Cb of the filtered decoded image P_FL. Further, the color difference component Cr and the color difference component Cb of the generated filtered decoded image P_FL are stored in the buffer memory 15.

  As shown in FIG. 5, the color difference adaptive filter unit 32 includes a switch unit 321, a Cr filter processing unit 322, and a Cb filter processing unit 323. The switch unit 321 includes a switch unit 321a and a switch unit 321b.

(Switch unit 321)
The switch unit 321 switches whether to perform adaptive filter processing on the color difference component Cr and the color difference component Cb. If the switch unit 321a is on, the color difference component Cr of the deblocked decoded image P_DB is supplied to the Cr filter processing unit 322. If the switch unit 321b is on, the color difference component Cb of the deblocked decoded image P_DB is supplied to the Cb filter processing unit 323. FIG. 9 shows an on / off state of the switch 321a and the switch 321b.

  When alf_chroma_idc is 0, filter processing for the color difference component Cr and the color difference component Cb is not performed. When alf_chroma_idc is 1, the color difference component Cr is filtered. When alf_chroma_idc is 2, the color difference component Cb is filtered. When alf_chroma_idc is 3 or 4, filter processing of the color difference component Cr and the color difference component Cb is performed.

(Switch part 321a)
The switch unit 321a is turned on when alf_chroma_idc is 1, 3, or 4. When ON, the color difference component Cr of the deblocked decoded image P_DB is supplied to the Cr filter processing unit 322, and when OFF, the color difference component Cr of the deblocked decoded image P_DB is used as the color difference component Cr of the filtered decoded image P_FL. Output.

(Switch unit 321b)
The switch unit 321b is turned on when alf_chroma_idc is 2, 3, or 4. When ON, the color difference component Cb of the deblocked decoded image P_DB is supplied to the Cb filter processing unit 323, and when OFF, the color difference component Cb of the deblocked decoded image P_DB is used as the color difference component Cb of the filtered decoded image P_FL. Output.

(Adaptive filtering)
The adaptive filter processing is performed by the following operations in the Cr filter processing unit 322, the Cb filter processing unit 323, and the luminance adaptive filter unit 33.

  The pixel value of the filter target pixel is represented as SF (x ′, y ′), and the pixel values in or around the target macroblock in the deblocked decoded image P_DB (hereinafter also referred to as “pre-filter image”) When expressed as S (x, y), the filter processing unit calculates the pixel value SF (x ′, y ′) by the following equation (1).

Here, the coordinates (x, y) may be the same coordinates as the coordinates (x ′, y ′), or different coordinates as long as they have a one-to-one correspondence. AI (i, j) represents a filter coefficient to be multiplied by the pixel value S (x + i, y + j) of the pre-filter image, and corresponds to the filter coefficient included in the luminance filter information or the color difference filter information of the filter parameter FP. doing. OI represents an offset included in the filter coefficient group I. R represents an area referred to in the filter processing (hereinafter also referred to as “filter reference area R”), and is set according to the position of the filter target pixel. On the other hand, the above-described filter reference range (also referred to as “filter reference range RA”) is defined as the union of filter reference regions R for each filter target pixel. The filter reference range RA can also be expressed as a set of pixels required for calculating all pixel values of the filtered image in the target unit region.

  FIG. 10A shows the filter reference region R and the filter reference range RA when the target unit region UR is 8 × 8 pixels and the filter reference region is 5 × 5 taps. In FIG. 10A, the hatched pixels indicate the filter target pixels S (x ′, y ′).

  An example of how to assign filter coefficients to each pixel included in the filter reference region R is shown in FIG. Also in FIG. 10B, the hatched pixels indicate the filter target pixels S (x ′, y ′). As shown in FIG. 10B, each filter coefficient can be assigned to each pixel included in the filter reference region R so as to have a rotational symmetry of 180 degrees.

  However, the present embodiment is not limited to this, and the assignment of each filter coefficient to each pixel value may not have rotational symmetry. Further, the filter reference region R may be a rhombus region constituted by pixels whose city distance from the filter target pixel is Ncb or less in units of pixels, or regions having other shapes. Good.

  The method of assigning the filter coefficient to each pixel included in the filter reference region R and the shape of the filter reference region R may be appropriately set according to the configuration of the moving picture encoding device that generates the encoded data # 1. Good.

(Cr filter processing unit 322)
The Cr filter processing unit 322 uses the filter coefficient group HCr supplied from the chrominance adaptive filter coefficient derivation unit 311 for the chrominance component Cr of the deblocked decoded image P_DB supplied from the switch unit 321. To generate a color difference component Cr of the filtered decoded image P_FL.

(Cb filter processing unit 323)
The Cb filter processing unit 323 performs adaptive filter processing using the filter coefficient group HCb supplied from the color difference adaptive filter coefficient deriving unit 311 for the color difference component Cb of the deblocked decoded image P_DB supplied from the switch unit 321. To generate a color difference component Cb of the filtered decoded image P_FL.

(Luminance adaptive filter unit 33)
The luminance adaptive filter unit 33 performs adaptive filter processing on the luminance component Y of the deblocked decoded image P_DB using luminance filter information supplied from the filter parameter FP, and the luminance component Y of the filtered decoded image P_FL. Is generated.

(Moving picture encoding device 2)
A configuration of the moving picture encoding apparatus 2 according to the present embodiment will be described with reference to FIGS. The moving image encoding apparatus 2 includes H.264 as a part thereof. H.264 / MPEG-4. It is an encoding device including a technique adopted in a test model HM of AVC, VCEG (Video Coding Expert Group), and HEVC (High Efficiency Video Coding) proposed as a successor codec.

  FIG. 11 is a block diagram illustrating a configuration of the moving image encoding device 2. As illustrated in FIG. 11, the moving image encoding device 2 includes a transform / quantization unit 21, a variable length code encoding unit 22, an inverse quantization / inverse transform unit 23, a buffer memory 24, an intra-predicted image generation unit 25, The inter prediction image generation unit 26, the motion vector detection unit 27, the prediction scheme control unit 28, the motion vector redundancy deletion unit 29, an adder 41, a subtractor 42, a deblocking filter 43, and an adaptive filter 44 are provided. The moving image encoding device 2 is a device that generates encoded data # 1 by encoding moving image # 10 (encoding target image).

(Transformation / quantization unit 21)
The transform / quantization unit 21 performs (1) DCT transform (Discrete Cosine Transform) on the prediction residual D obtained by subtracting the predicted image Pred from the encoding target image, and (2) DCT coefficients obtained by the DCT transform. (3) The quantized prediction residual QD obtained by the quantization is supplied to the variable-length code encoding unit 22 and the inverse quantization / inverse transform unit 23. The transform / quantization unit 21 selects (1) a quantization step QP used for quantization for each TU, and (2) sets a quantization parameter difference Δqp indicating the magnitude of the selected quantization step QP. The variable length code encoding unit 22 is supplied, and (3) the selected quantization step QP is supplied to the inverse quantization / inverse transform unit 23. Here, the quantization parameter difference Δqp is the quantization parameter qp ′ relating to the TU that has been DCT transformed / quantized immediately before from the value of the quantization parameter qp (QP = 2 ^{pq / 6} ) relating to the TU to be DCT transformed / quantized. The difference value obtained by subtracting the value of.

(Variable length code encoder 22)
The variable length code encoding unit 22 includes (1) a quantized prediction residual QD and Δqp supplied from the transform / quantization unit 21, and (2) a quantization parameter PP supplied from a prediction scheme control unit 28 described later, (3) The encoded parameter # 1 is generated by variable-length encoding the filter parameter FP supplied from the adaptive filter 44 described later.

(Inverse quantization / inverse transform unit 23)
The inverse quantization / inverse transform unit 23 (1) inversely quantizes the quantized prediction residual QD, (2) performs inverse DCT (Discrete Cosine Transform) transformation on the DCT coefficient obtained by the inverse quantization, and (3) The prediction residual D obtained by the inverse DCT transform is supplied to the adder 41. When the quantization prediction residual QD is inversely quantized, the quantization step QP supplied from the transform / quantization unit 21 is used. Note that the prediction residual D output from the inverse quantization / inverse transform unit 23 is obtained by adding a quantization error to the prediction residual D input to the transform / quantization unit 21. Common names are used for this purpose.

(Intra prediction image generation unit 25)
The intra predicted image generation unit 25 generates a predicted image Pred_Intra related to each partition. Specifically, (1) a prediction mode used for intra prediction is selected for each partition, and (2) a prediction image Pred_Intra is generated from the decoded image P using the selected prediction mode. The intra predicted image generation unit 25 supplies the generated intra predicted image Pred_Intra to the prediction method control unit 28.

  In addition, the intra prediction image generation unit 25 identifies the prediction index PI for each partition from the prediction mode selected for each partition and the size of each partition, and specifies a prediction index indicating the prediction index PI for each partition. Information is supplied to the prediction method control unit 28.

(Motion vector detection unit 27)
The motion vector detection unit 27 detects a motion vector mv regarding each partition. Specifically, (1) the filtered decoded image P_FL ′ to be used as a reference image is selected, and (2) the target partition is searched by searching for the region that best approximates the target partition in the selected filtered decoded image P_FL ′. Detects a motion vector mv. Here, the filtered decoded image P_FL ′ is obtained by performing deblocking processing by the deblocking filter 43 and adaptive filtering processing by the adaptive filter 44 on the decoded image that has already been decoded. It is an image, and the motion vector detection unit 27 can read out the pixel value of each pixel constituting the filtered decoded image P_FL ′ from the buffer memory 24. The motion vector detection unit 27 supplies the detected motion vector mv to the inter predicted image generation unit 26 and the motion vector redundancy deletion unit 29 together with the reference image index RI that specifies the filtered decoded image P_FL ′ used as the reference image. To do. Note that for a partition that performs bi-directional prediction (weighted prediction), two filtered decoded images P_FL1 ′ and P_FL2 ′ are selected as reference images, and each of the two filtered decoded images P_FL1 ′ and P_FL2 ′ is selected. Corresponding motion vectors mv1 and mv2 and reference image indexes RI1 and RI2 are supplied to the inter prediction image generation unit 26 and the motion vector redundancy deletion unit 29.

(Inter prediction image generation unit 26)
The inter prediction image production | generation part 26 produces | generates the motion compensation image mc regarding each inter prediction partition. Specifically, using the motion vector mv supplied from the motion vector detection unit 27, the motion compensated image mc is obtained from the filtered decoded image P_FL ′ designated by the reference image index RI supplied from the motion vector detection unit 27. Generate. Similar to the motion vector detection unit 27, the inter predicted image generation unit 26 can read out the pixel values of each pixel constituting the filtered decoded image P_FL ′ from the buffer memory 24. The inter prediction image generation unit 26 supplies the generated motion compensated image mc (inter prediction image Pred_Inter) together with the reference image index RI supplied from the motion vector detection unit 27 to the prediction method control unit 28. For the partition with bi-directional prediction (weighted prediction), (1) the motion compensated image mc1 is generated from the filtered decoded image P_FL1 ′ specified by the reference image index RI1 using the motion vector mv1, and (2 ) A motion compensated image mc2 is generated from the filtered reference image P_FL2 ′ designated by the reference image index RI2 using the motion vector mv2, and (3) an offset value is added to the weighted average of the motion compensated image mc1 and the motion compensated image mc2. Is added to generate the inter predicted image Pred_Inter.

(Prediction method control unit 28)
The prediction scheme control unit 28 compares the intra predicted image Pred_Intra and the inter predicted image Pred_Inter with the encoding target image, and selects whether to perform intra prediction or inter prediction. When the intra prediction is selected, the prediction scheme control unit 28 supplies the intra prediction image Pred_Intra as the prediction image Pred to the adder 41 and the subtractor 42 and also predicts the prediction index PI supplied from the intra prediction image generation unit 25. The parameter PP is supplied to the variable length code encoder 22. On the other hand, when the inter prediction is selected, the prediction scheme control unit 28 supplies the inter prediction image Pred_Inter as the prediction image Pred to the adder 41 and the subtractor 42 and the reference image index supplied from the inter prediction image generation unit 26. RI and an estimated motion vector index PMVI and a motion vector residual MVD supplied from a motion vector redundancy deleting unit 29 (described later) are supplied to the variable length code encoding unit 22 as prediction parameters PP.

  The subtracter 42 generates a prediction residual D by subtracting the prediction image Pred selected by the prediction method control unit 28 from the encoding target image. The prediction residual D generated by the subtractor 42 is DCT transformed / quantized by the transform / quantization unit 21 as described above. On the other hand, by adding the prediction image Pred selected by the prediction method control unit 28 to the prediction residual D generated by the inverse quantization / inverse conversion unit 23, the adder 41 generates a local decoded image P. Generated. The local decoded image P generated by the adder 41 is stored in the buffer memory 24 as a filtered decoded image P_FL after passing through the deblocking filter 43 and the adaptive filter 44, and is used as a reference image in inter prediction.

(Motion vector redundancy deletion unit 29)
The motion vector redundancy deletion unit 29 deletes redundancy in the motion vector mv detected by the motion vector detection unit 27. Specifically, (1) an estimation method used for estimating the motion vector mv is selected, (2) an estimated motion vector pmv is derived according to the selected estimation method, and (3) the estimated motion vector pmv is subtracted from the motion vector mv. As a result, a motion vector residual MVD is generated. The motion vector redundancy deletion unit 29 supplies the generated motion vector residual MVD to the prediction method control unit 28 together with the estimated motion vector index PMVI indicating the selected estimation method.

(Deblocking filter 43)
The deblocking filter 43 determines the block boundary in the decoded image P when the difference between the pixel values of pixels adjacent to each other via the block boundary in the decoded image P or the macroblock boundary is smaller than a predetermined threshold value, or By performing deblocking processing on the macroblock boundary, an image near the block boundary or the macroblock boundary is smoothed. The image subjected to the deblocking process by the deblocking filter 43 is output to the adaptive filter 44 as a deblocked decoded image P_DB.

(Adaptive filter 44)
FIG. 12 is a block diagram showing the configuration of the adaptive filter 44. As shown in FIG. 12, the adaptive filter 44 includes a color difference adaptive filter unit 441 and a luminance adaptive filter unit 444. The adaptive filter 44 generates a filtered decoded image P_FL by performing an adaptive filter process on the deblocked decoded image P_DB supplied from the deblocking filter 43. The filtered decoded image P_FL that has been filtered by the adaptive filter 44 is stored in the buffer memory 24. The adaptive filter 44 generates a filter parameter FP and supplies it to the variable length code encoding unit 22.

(Color difference adaptive filter unit 441)
As illustrated in FIG. 12, the color difference adaptive filter unit 441 includes a color difference filter information determination unit 442 and an adaptive filter unit 443. The color difference adaptive filter unit 441 performs color difference filter information and color difference component Cr of the filtered decoded image P_FL from the color difference component Cr and color difference component Cb of the deblocked decoded image P_DB, color difference component Cr of the moving image # 10, and color difference component Cb. Component Cb is generated.

(Color difference filter information determination unit 442)
As illustrated in FIG. 13, the color difference filter information determination unit 442 includes a color difference filter coefficient calculation unit 4421 and a color difference filter coefficient determination unit 4422. The color difference filter information determination unit 442 determines the color difference filter information and supplies it to the adaptive filter unit 443 and the variable length code encoding unit 22.

(Color difference filter coefficient calculation unit 4421)
The color difference filter coefficient calculation unit 4421 calculates a filter coefficient group so that the square error between the color difference component of the deblocked decoded image P_DB and the color difference component of the encoding target image (moving image # 10) is minimized. . The color difference filter coefficient calculation unit 4421 uses a common filter coefficient calculation unit (not shown). The common filter coefficient calculation unit is a means used in common for the luminance component and the color difference component, and the square error between the designated color component and the deblocked decoded image and the encoding target image in the designated region. The filter coefficient group is calculated so as to be minimized. The luminance component Y, the color difference component Cb, the color difference component Cr, and both the color difference component Cb and the color difference component Cr can be specified, and the square error of each of them is given by the following (2), (3), (4) , (5).

  Note that S (x, y), SCb (x, y), and SCr (x, y) are pixels whose coordinates are (x, y) among the pixels included in the deblocked decoded image P_DB. The pixel values of the luminance component Y, the color difference component Cb, and the color difference component Cr are represented. ST (x, y), STCb (x, y), and STCr (x, y) are the pixels included in the encoding target image. Of these, the pixel values of the luminance component Y, the color difference component Cb, and the color difference component Cr of the pixel whose coordinates are (x, y) are represented.

The filter coefficient calculation unit 4421 performs the following three calculations. (Calculation 1) The filter coefficient groups aI (i, j) and oI obtained by minimizing the expression (3) are inversely quantized to obtain alf_coeff_Cr.
(Calculation 2) The filter coefficient groups aI (i, j) and oI obtained by minimizing the equation (4) are inversely quantized to obtain alf_coeff_Cb.
(Calculation 3) The filter coefficient groups aI (i, j) and oI obtained by minimizing the expression (5) are inversely quantized to obtain alf_coeff_chroma. Here, the inverse quantization process is performed according to the quantization bit depth filter_bitdepth of the filter coefficient. Here, the reciprocal 1 <filter_bitdepth of the quantization step determined from the quantization bit depth is applied, and this is performed according to the following equation (6).
Here, coeff represents one of alf_coeff_Cr, alf_coeff_Cb, and alf_coeff_chroma, and i represents a subscript of the filter coefficient a shown in FIG. k1 and k2 are determined so that the positional relationship with i corresponds.

(Color difference filter coefficient determination unit 4422)
The color difference filter coefficient determination unit 4422 is supplied with the filter coefficient group alf_coeff_Cr, the filter coefficient group alf_coeff_Cb, and the filter coefficient group alf_coeff_chroma from the color difference filter coefficient calculation unit 4421. The color difference filter coefficient determination unit 4422 obtains the coding cost in each mode of alf_chroma_idc by the following processing 1 to processing 5, and obtains the optimum alf_chroma_idc by processing 6. The encoding cost is a rate calculated from the square error obtained by comparing the image obtained by the adaptive filter processing in each mode and the encoding target image, and the code amount of the filter coefficient group used in each mode. Use distortion costs.

<When the first color difference component C1 is determined in advance>
(Process 1) The encoding cost 0 of mode 0 is obtained from the square error when the adaptive filter processing is not performed on the color difference component Cr and the color difference component Cb and the code amount when the filter coefficient group is not encoded.

  (Processing 2) The encoding cost 1 of mode 1 is obtained from the square error when adaptive filter processing is performed only on the color difference component Cr using the filter coefficient group alf_coeff_Cr and the code amount of the filter coefficient group of the color difference component Cr. .

  (Process 3) The encoding cost 2 of mode 2 is obtained from the square error when the adaptive filter processing is performed only on the color difference component Cb using the filter coefficient group alf_coeff_Cb and the code amount of the filter coefficient group of the color difference component Cb. .

  (Process 4) The encoding cost 3 of mode 3 is obtained from the square error when the adaptive filter processing is performed on the color difference component Cr and the color difference component Cb using the filter coefficient group alf_coeff_chroma and the code amount of the filter coefficient group alf_coeff_chroma. .

  (Process 5) Square error when adaptive filter processing is performed on the color difference component Cr and the color difference component Cb using the filter coefficient group alf_coeff_Cr and the filter coefficient group alf_coeff_Cb, and the independent filter coefficient group alf_coeff_C1 and the first color difference component C1 The encoding cost 4 of mode 4 is obtained from the code amount of the dependent filter coefficient group alf_coeff_C2 for deriving the two-color difference component C2.

  (Process 6) A mode in which the coding cost (coding cost 1 to coding cost 4) of the five modes is the minimum is defined as alf_chroma_idc. That is, if the coding cost of mode K is the minimum, alf_chroma_idc = K.

<When the first color difference component C1 is determined by sw_flag>
When sw_flag is used, instead of the process 5 and the process 6, the following process 7, process 8, and process 9 are performed to obtain the optimum alf_chroma_idc and sw_flag.

  (Process 7) The square error when adaptive filter processing is performed on the color difference component Cr and the color difference component Cb using the filter coefficient group alf_coeff_Cr and the filter coefficient group alf_coeff_Cb, and when sw_flag = 0, that is, the first color difference component C1 is In the case where the color difference component Cr and the second color difference component C2 are the color difference components Cb, the code amount of the filter coefficient group alf_coeff_C1 and the subordinate filter coefficient group alf_coeff_C2 for deriving the second color difference component C2 is set to mode 4 and sw_flag = 0. The encoding cost 40 is obtained.

  (Process 8) The square error when adaptive filter processing is applied to the color difference component Cr and the color difference component Cb using the filter coefficient group alf_coeff_Cr and the filter coefficient group alf_coeff_Cb, and when sw_flag = 1, that is, the first color difference component C1 is When the color difference component Cb and the second color difference component C2 are the color difference component Cr, the code amount of the mode 4 and sw_flag = 1 is determined from the code amounts of the filter coefficient group alf_coeff_C1 and the subordinate filter coefficient group alf_coeff_C2 for deriving the second color difference component C2. An encoding cost 41 is obtained.

  (Process 9) A mode in which the encoding cost (encoding cost 0 to encoding cost 3, encoding cost 40, encoding cost 41) of the six modes is the minimum is defined as alf_chroma_idc. Furthermore, when mode 4 is the minimum, the smaller one is selected from the encoding cost 40 and the encoding cost 41, and sw_flag is defined. That is, sw_flag = 0 is set when the coding cost 40 is small, and sw_flag = 1 is set when the coding cost 41 is small.

(Adaptive filter unit 443)
The adaptive filter unit 443 performs adaptive filter processing on the color difference component Cr and the color difference component Cb of the deblocked decoded image P_DB using the color difference filter information supplied from the color difference filter information determination unit 442, and performs filtered decoding. A color difference component Cr and a color difference component Cb of the image P_FL are generated. Since the process of the adaptive filter unit 443 is the same as the process of the color difference adaptive filter unit 32 described above, the description thereof is omitted here.

(Luminance adaptive filter unit 444)
The luminance adaptive filter unit 444 uses the luminance filter information calculated from the moving image # 10 and the luminance component Y of the deblocked decoded image P_DB to perform adaptive filter processing on the luminance component Y of the deblocked decoded image P_DB. Apply. The luminance adaptive filter unit 444 generates a luminance component Y, filter on / off information, and luminance filter information of the filtered decoded image P_FL. In addition, since the process of the brightness | luminance adaptive filter part 444 is the same as the process of the brightness | luminance adaptive filter part 33 mentioned above, description is abbreviate | omitted here.

  In the configuration of the first embodiment, different filter coefficient groups can be used for the filter coefficient group of the color difference component Cr and the filter coefficient group of the color difference component Cb. Therefore, when a common filter coefficient group is used between the color difference components. In comparison, the image quality of the color difference component can be improved. Furthermore, when encoding the filter coefficients of a plurality of color difference components using the property that the color difference component filter coefficients are often close to each other, the difference value between one filter coefficient and the other filter coefficient is used. Thus, by encoding as a dependent filter coefficient group, the code amount of the filter coefficient can be reduced. Moreover, the code amount of the filter coefficient can be further reduced by appropriately selecting the independent filter coefficient group that is the color difference component that is not encoded as the difference value. The difference value between the filter coefficient group HCb of the chrominance component Cb and the filter coefficient group HCr of the chrominance component Cr does not change even if either filter coefficient group is encoded as a component that is not a difference value. That is, even if the difference value is calculated by HCb [i] −HCr [i] or the difference value is calculated by HCr [i] −HCb [i], the absolute value is equal only by reversing the sign, When the difference value is encoded, both code amounts are equal. On the other hand, the filter coefficient group HCr of the chrominance component Cr and the filter coefficient group HCb of the chrominance component Cb are generally different in value, and therefore independent of the difference filter coefficient group depending on which of them is encoded as an independent filter coefficient group. The total code amount consisting of filter coefficient groups is different. Therefore, the filter coefficient group of the color difference component with a small code amount is stored in the filter coefficient group of the first color difference component C1, and the other color difference component is set as the second color difference component C2 and is decoded from the difference value between the color difference components. By doing so, the amount of codes can be reduced. In fact, according to the knowledge obtained by the inventor through experiments, the code amount of the filter coefficient group HCr and the filter coefficient group HCb may be twice different. Is possible.

  In the configuration of the first embodiment, the method of deriving the filter coefficient group HC2 from the dependent filter coefficient group alf_coeff_C2 when alf_chroma_idc is 4 is not limited to the above description. In the above description, all the filter coefficients of the filter coefficient group HC2 are derived from the difference between alf_coeff_C2 and alf_coeff_C1, but some filter coefficients are derived from the difference between alf_coeff_C2 and alf_coeff_C1, and other filter coefficients are derived from alf_coeff_C2. It does not matter if the configuration is That is, it means that some filter coefficients of the filter coefficient group HC2 are encoded as difference values, and other filter coefficients are encoded with values (non-difference values) that are not difference values.

For example, it is preferable to encode a filter coefficient other than the offset as a difference value and encode the offset using a non-difference value. In particular,
When AlfNumCoeffChroma-1 is the offset, the calculation method of the filter coefficient group HC2 is expressed by the following equation (7).
Here, i is an integer from 0 to AlfNumCoeffChroma-1.

  Also, a differential encoding flag indicating whether the offset component is encoded as a difference value or non-difference value is included in the encoded data # 1, and the moving image decoding apparatus decodes the flag Depending on the value, the decoding method of the filter coefficient may be changed. This is due to the inventor's knowledge that generally there is often no correlation between offsets of different color difference components. When there is no correlation, the absolute value of the difference value may increase by taking the difference value between the offsets. In general, the filter coefficients of the filter coefficient group including the offset are encoded such that a value close to 0 is expressed by a short code length by using the concentration to 0. In such an encoding method, a difference value that increases the absolute value leads to an increase in the code amount. Therefore, it is appropriate not to use the difference value for the offset.

  Further, in the method using the differential encoding flag, the code amount can be reduced not only when the offsets of different filter coefficient groups are not approximated but also when they are approximated. For this reason, the method using the differential encoding flag indicating whether or not to take the difference value of the offset is not only used for encoding the filter coefficient between the color difference components, but in general, other filter coefficients that have already been decoded are used as other filters. It can be used when decoding using a difference value from a coefficient. For example, the present invention can be used when decoding a filter coefficient to be decoded from a previously decoded slice, a decoded filter coefficient of the current slice, or the like.

  Note that the color space handled in the first embodiment is not limited to the YUV space, and can be extended to other color spaces such as RGB, CMYK, and XYZ. Even in this case, a flag (which is a flag corresponding to alf_chroma_idc and more generally referred to as a filter mode) indicating which component is to be filtered in at least two color components included in the color space is decoded. To do. This also means that it can be expanded to filter processing between YU, YV, and YUV without being limited to filtering between UVs in the YUV space. Furthermore, when a plurality of components are filtered, a specific color component is a component to be encoded as an independent filter coefficient group, and filter coefficients of other color components are encoded as a dependent filter coefficient group. Thus, the code amount of the filter coefficient can be reduced. Furthermore, by encoding a flag (corresponding to sw_flag) indicating which color component is encoded as an independent filter coefficient group, the code amount of the filter coefficient can be further reduced.

  Further, instead of the filter mode of the color difference filter mode alf_chroma_idc described in the first embodiment, another filter mode having the same kind of function can be used. The color difference filter mode alf_chroma_idc has the function of indicating the following two pieces of information, but can be encoded as two pieces of information that play the role of function 1 and function 2.

  (Function 1) A function indicating whether or not to perform filter processing on each color component in at least two color components subjected to filter processing by the adaptive filter 30.

  (Function 2) A function indicating whether a common filter coefficient group is used for each color component or an individually derived filter coefficient group is used when there are two color components to be filtered by the adaptive filter 30 .

  FIG. 29 shows filter parameter syntax when the first filter mode alf_chroma_idc1 and the second filter mode alf_chroma_idc2 are used instead of the color difference filter mode alf_chroma_idc. The first filter mode alf_chroma_idc1 takes a value of 0 to 3, and the second filter mode alf_chroma_idc2 takes a value of 0 or 1. The first filter mode alf_chroma_idc1 indicates whether or not to perform filter processing on each color component of the color difference component Cr and the color difference component Cb, and plays the role of the function 1 described above. The second filter mode alf_chroma_idc2 indicates whether to use a shared filter coefficient group between two color difference components or to use individually derived filter coefficient groups, and plays the role of the function 2 described above.

The color difference adaptive filter coefficient deriving unit 311 does not decode the filter coefficient group when the first filter mode alf_chroma_idc1 is 0. When the first filter mode alf_chroma_idc1 is 1, the filter coefficient group HCr is decoded from alf_coeff_Cr. When the first filter mode alf_chroma_idc1 is 2, the filter coefficient group HCb is decoded from alf_coeff_Cb. When the first filter mode alf_chroma_idc1 is 3, the second filter mode alf_chroma_idc2 is further decoded. When the second filter mode alf_chroma_idc2 is 0
The filter coefficient group HCr and the filter coefficient group HCb are decoded from alf_coeff_chroma. When the second filter mode alf_chroma_idc2 is 1, the filter coefficient group HCr and the filter coefficient group HCb are decoded from the independent filter coefficient group alf_coeff_C1 and the dependent filter coefficient group alf_coeff_C2.

  FIG. 30A shows the relationship between the first filter mode alf_chroma_idc1 and the value of the color difference component Cr and the presence / absence of the filter processing of the color difference component Cb. FIG. 30B shows the relationship between the second filter mode alf_chroma_idc2 and the filter coefficient group included in the encoded data # 1. When the second filter mode alf_chroma_idc2 is 0, one common filter coefficient group _alf_coeff_chroma is included in the encoded data # 1, and the corresponding filter coefficient group is used for the filter processing of the color difference component Cr and the color difference component Cb. When the second filter mode alf_chroma_idc2 is 1, two filter coefficient groups alf_coeff_Cr and a filter coefficient group alf_coeff_Cb are included in the encoded data # 1. Corresponding filter coefficient groups are used for filtering each color difference component.

[Embodiment 2]
Below, the 2nd Embodiment of this invention is described with reference to FIGS. 14-24, FIG. 26, FIG. The adaptive filter according to the present embodiment encodes an on / off flag that specifies on / off of the filter process for each of the coding units up to a predetermined division depth. This embodiment is characterized in that the code amount of the on / off flag is reduced by using a common on / off flag among a plurality of color components. Specifically, any one of the control patterns 2 to 4 among the following four control patterns is used as a configuration.

  (Control Pattern 1) When performing on / off control in units of areas for the luminance component Y using one set of on / off flags. In this case, the color difference component does not perform on / off control in units of regions.

  (Control pattern 2) When on / off control of each color component is performed using a set of on / off flags common to the luminance component Y, the color difference component Cb, and the color difference component Cr.

  (Control Pattern 3) Using two sets of on / off flags, on / off control of the luminance component Y is performed with one set of on / off flags, and common on / off control is performed with the color difference component Cr and the color difference component Cb using another set of on / off flags. If you do.

  (Control pattern 4) When independent on / off control is performed for each of the luminance component Y, the color difference component Cb, and the color difference component Cr by using three sets of on / off flags.

  However, the scope of application of the second embodiment of the present invention is not limited to this. That is, as will be apparent from the following description, the features of the present invention can be realized without assuming a plurality of frames. That is, the present invention can be applied to a general decoding apparatus and a general encoding apparatus regardless of whether the target is a moving image or a still image.

(Configuration of encoded data # 3)
Prior to detailed description of the video encoding device 4 and the video decoding device 3 according to the present embodiment, the encoded data # 3 generated by the video encoding device 4 and decoded by the video decoding device 3 is described. The data structure will be described. The data structure of the encoded data # 3 is substantially the same as the data structure of the encoded data # 1 according to the first embodiment, but the configuration of the filter parameter FP is different. FIG. 14 is a diagram showing the data structure of the filter on / off information included in the filter parameter FP of the encoded data # 3. FIGS. 15 to 18 show the filter parameter FP (denoted as alf_param) of the encoded data # 3. It is a figure which shows each syntax contained. 15 to 18 are diagrams showing syntaxes included in the filter parameter FP in the control patterns 1 to 4, respectively.

  As shown in FIGS. 15 to 18, the filter parameter FP of the encoded data # 3 includes (1) syntax adaptive_loop_filter_flag that specifies whether or not to perform adaptive filter processing on the target slice, and (2) adaptive filter. Syntax alf_cu_control_flag that specifies whether or not processing on / off is controlled for each coding unit, (3) Syntax that specifies the maximum division depth from the maximum coding unit for a coding unit that is subject to on / off control. (Hierarchy designation information) alf_cu_control_max_depth, (4) The syntax alf_length_cu_control_info for designating the number of coding units to be subjected to on / off control is included in common to all control patterns.

  In the case of the control pattern 1, as shown in FIG. 15, an on / off flag alf_cu_flag is included in the filter parameter FP for each coding unit to be subjected to on / off control.

  In the case of the control pattern 2, as shown in FIG. 16, the on / off flag alf_cu_flag for adaptive filter processing and the flag alf_cu_control_flag_chroma for designating whether to apply the on / off flag alf_cu_flag to the color difference adaptive filter are included in the filter parameter FP.

  In the case of the control pattern 3, as shown in FIG. 17, the on / off flag alf_cu_flag_luma related to the adaptive filter for the luminance component Y and the on / off flag alf_cu_flag_chroma related to the adaptive filter for the color difference component Cr and the color difference component Cb are included in the filter parameter FP.

  In the case of the control pattern 4, as shown in FIG. 18, on / off flags relating to adaptive filters of the luminance component Y, the color difference component Cr, and the color difference component Cb, alf_cu_flag_luma, alf_cu_flag_cr, and alf_cu_flag_cb are included in the filter parameter FP.

  Note that i in FIGS. 15 to 18 is an index of an on / off flag used for control of adaptive filter processing, and is an integer from 0 to NumAlfCuFlag-1. NumAlfCuFlag is the total number of on / off flags for performing adaptive filter processing, and is determined by the hierarchy designation information alf_cu_control_max_depth and the CU structure. Note that NumAlfCuFlag can be explicitly encoded in the encoded data instead of determining NumAlfCuFlag from the hierarchy designation information alf_cu_control_max_depth and the CU structure.

(Moving picture decoding apparatus 3)
Below, the moving image decoding apparatus 3 which concerns on this embodiment is demonstrated with reference to FIGS. In the following, the same parts as those already described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 19 is a block diagram showing a configuration of the moving picture decoding apparatus 3. As illustrated in FIG. 19, the video decoding device 3 includes an adaptive filter 50 instead of the adaptive filter 30 included in the video decoding device 1. The filter parameter FP included in the encoded data # 3 is supplied to the adaptive filter 50. In addition, since the other structure of the moving image decoding apparatus 3 is the same as the moving image decoding apparatus 1, description is abbreviate | omitted.

(Adaptive filter 50)
The adaptive filter 50 performs an adaptive filter process on the deblocked decoded image P_DB to generate a filtered decoded image P_FL. FIG. 20 is a block diagram showing the configuration of the adaptive filter 50. As illustrated in FIG. 20, the adaptive filter 50 includes an adaptive filter information restoration unit 51, a color difference adaptive filter unit 52, and a luminance adaptive filter unit 53.

(Adaptive filter information restoration unit 51)
The adaptive filter information restoration unit 51 decodes the filter parameter FP. As shown in FIG. 20, the adaptive filter information restoration unit 51 includes an on / off information restoration unit 511 and a filter information restoration unit 512.

(On / off information restoration unit 511)
The on / off information restoration unit 511 decodes the luminance component Y, the chrominance component Cr, and the chrominance component Cb on / off flags AlfFilterFlagY, AlfFilterFlagCb, and AlfFilterFlagCr from the filter on / off information included in the filter parameter FP.

  FIG. 26A shows an example of coding unit division for the luminance component Y in the maximum coding unit LCU when the value of alf_cu_control_max_depth is 2, along with a branch diagram representing a hierarchical structure. All coding units can be identified by an index assigned in raster scan order. FIG. 26B shows the correspondence between the filter processing control and the on / off flag AlfFilterFlagY [i] for the divided region shown in FIG. When the on / off flag AlfFilterFlagY [i] for the coding unit including the target unit region is 0, it is specified that adaptive filter processing is not performed on the coding unit. On the other hand, when the on / off flag AlfFilterFlagY [i] for the coding unit including the target unit region is 1, it specifies that adaptive filter processing is performed on the coding unit. AlfFilterFlagCr and AlfFilterFlagCb also specify whether or not to perform adaptive filter processing for the coding units of the color difference component Cr and the color difference component Cb in the same manner.

  The correspondence relationship between the ON / OFF flag in each encoded data # 3 and the ON / OFF flag used for control in the case of control pattern 1 to control pattern 4 is shown in the table of FIG. The correspondence relationship between on / off flags AlfFilterFlagY, AlfFilterFlagCr, AlfFilterFlagCb used for control and on / off flags alf_cu_flag, alf_cu_flag_luma, alf_cu_flag_chroma, alf_cu_flag_cr, alf_cu_flag_cb in encoded data # 3 will be described.

  As described above, AlfFilterFlagY, AlfFilterFlagCr, and AlfFilterFlagCb mean on / off flags used for adaptive filter control for luminance component Y, chrominance component Cr, and chrominance component Cb, and alf_cu_flag and alf_cu_flag_luma, alf_cu_flag_chroma, alf_cu_flag_cr_c, cf The ON / OFF flag in the encoded data # 3.

  In the case of control pattern 1, the on / off flag alf_cu_flag is decoded for each coding unit to be subjected to on / off control. At this time, as shown in FIG. 21, alf_cu_flag is stored in AlfFilterFlagY, and a value of 1 is stored in AlfFilterFlagCb and AlfFilterFlagCr.

  In the case of the control pattern 2, the flag alf_cu_flag that specifies on / off of the adaptive filter process and the flag alf_cu_control_flag_chroma that specifies whether the on / off flag alf_cu_flag is applied to the color difference adaptive filter are decoded. That is, alf_cu_control_flag_chroma is a flag for selecting whether the decoded on / off flag alf_cu_flag is used as an on / off flag for the luminance component Y, or an on / off flag common to the luminance component Y, the color difference component Cr, and the color difference component Cb. At this time, as shown in FIG. 21, when alf_cu_control_flag_chroma is true, alf_cu_flag is decoded and stored in AlfFilterFlagY, AlfFilterFlagCb, and AlfFilterFlagCr. When alf_cu_control_flag_chroma is false, alf_cu_flag is decoded and stored in AlfFilterFlagY. 1 is always stored in AlfFilterFlagCb and AlfFilterFlagCr.

  In the case of the control pattern 3, the on / off flag alf_cu_flag_luma and the on / off flag alf_cu_flag_chroma are decoded. At this time, as shown in FIG. 21, alf_cu_flag_luma is stored in AlfFilterFlagY, and alf_cu_flag_chroma is stored in AlfFilterFlagCb and AlfFilterFlagCr.

  In the case of the control pattern 4, the on / off flags alf_cu_flag_luma, alf_cu_flag_cb, and alf_cu_flag_cr are decoded. At this time, as shown in FIG. 21, alf_cu_flag_luma, alf_cu_flag_cb, and alf_cu_flag_cr are stored in AlfFilterFlagY, AlfFilterFlagCb, and AlfFilterFlagCr, respectively.

(Filter information restoration unit 512)
The filter information restoration unit 512 uses the luminance filter information and the chrominance filter information included in the filter parameter FP, and the adaptive filter coefficient group HY of the luminance component Y, the adaptive filter coefficient group HCr of the chrominance component Cr, and the adaptive filter coefficient group of the chrominance component Cb. Decode HCb. The filter coefficient group HY is supplied to the luminance adaptive filter unit 53, and the filter coefficient group HCr and the filter coefficient group HCb are supplied to the color difference adaptive filter unit 52.

(Color difference adaptive filter unit 52)
The chrominance adaptive filter unit 52 refers to the on / off flag AlfFilterFlagCr and the on / off flag AlfFilterFlagCb, performs adaptive filter processing on the chrominance component Cr and the chrominance component Cb of the deblocked decoded image P_DB, and outputs the filtered decoded image P_FL. A color difference component Cr and a color difference component Cb are generated. Further, the color difference component Cr and the color difference component Cb of the generated filtered decoded image P_FL are stored in the buffer memory 15.

  As shown in FIG. 20, the color difference adaptive filter unit 52 includes a switch unit 521a, a switch unit 521b, a Cr filter processing unit 522, and a Cb filter processing unit 523.

(Switch unit 521a)
The switch unit 521a supplies the color difference component Cr of the deblocked decoded image P_DB to the Cr filter processing unit 522 when the on / off flag AlfFilterFlagCr is on. When it is off, the color difference component Cr of the deblocked decoded image P_DB is output as the color difference component Cr of the filtered decoded image P_FL.

(Switch unit 521b)
The switch unit 521b supplies the color difference component Cb of the deblocked decoded image P_DB to the Cb filter processing unit 523 when the on / off flag AlfFilterFlagCb is on. When OFF, the color difference component Cb of the deblocked decoded image P_DB is output as the color difference component Cb of the filtered decoded image P_FL.

(Cr filter processing unit 522)
The Cr filter processing unit 522 performs adaptive filter processing using the filter coefficient group HCr supplied from the filter information restoration unit 512 on the color difference component Cr of the deblocked decoded image P_DB supplied from the switch unit 521a. Thus, the color difference component Cr of the filtered decoded image P_FL is generated.

(Cb filter processing unit 523)
The Cb filter processing unit 523 performs adaptive filter processing using the filter coefficient group HCb supplied from the filter information restoration unit 512 on the color difference component Cb of the deblocked decoded image P_DB supplied from the switch unit 521b. Thus, the color difference component Cb of the filtered decoded image P_FL is generated.

(Luminance adaptive filter unit 53)
The luminance adaptive filter unit 53 refers to the on / off flag AlfFilterFlagY, performs adaptive filter processing on the luminance component Y of the deblocked decoded image P_DB, and generates the luminance component Y of the filtered decoded image P_FL. Further, the luminance component Y of the generated filtered decoded image P_FL is stored in the buffer memory 15.

  As shown in FIG. 20, the luminance adaptive filter unit 53 includes a switch unit 531 and a Y filter processing unit 532.

(Switch unit 531)
The switch unit 531 supplies the luminance component Y of the deblocked decoded image P_DB to the Y filter processing unit 532 when the on / off flag AlfFilterFlagY is on. When OFF, the luminance component Y of the deblocked decoded image P_DB is output as the luminance component Y of the filtered decoded image P_FL.

(Y filter processing unit 532)
The Y filter processing unit 532 performs adaptive filter processing using the filter coefficient group HY supplied from the filter information restoration unit 512 on the luminance component Y of the deblocked decoded image P_DB supplied from the switch unit 531. Thus, the luminance component Y of the filtered decoded image P_FL is generated.

(Configuration that allows selection of control patterns)
Note that the video decoding device 3 may be configured to be able to select a plurality of control patterns. In this case, the flag alf_cu_control_mode for selecting the control pattern is included in the filter parameter, and the moving picture decoding apparatus uses a control mode corresponding to the decoded alf_cu_control_mode. alf_cu_control_mode takes a value of 1 to 4, and control patterns 1 to 4 are selected for each value. The filter parameter syntax at this time is shown in FIG. When the control pattern 1 and the control pattern 2 can be selected as in this example, it is not necessary to decode the flag alf_cu_control_flag_chroma that specifies whether to apply to the adaptive filter processing of the color difference component. In alf_cu_control_flag_chroma, a configuration using an on / off flag for the luminance component and a configuration using a common on / off flag for the luminance component and the color difference component are switched. However, in the configuration in which the control pattern 1 and the control pattern 2 can be selected, the former is used as the control pattern 1. The same switching can be performed by treating the latter with the control pattern 2.

  Here, as a configuration for selecting a control pattern, the present embodiment is not limited to the above description, and a simpler configuration can also be used. As an example, control pattern 1 or control pattern 3 can be selected using flag alf_cu_control_mode for selecting a control pattern. That is, it is possible to select whether to use an on / off flag only for the luminance component Y or to use an independent on / off flag for the luminance component Y and the two color difference components. When alf_cu_control_mode is 1, control pattern 1 is selected, and when alf_cu_control_mode is 3, control pattern 3 is selected. The filter parameter syntax at this time is shown in FIG.

(Moving picture encoding device 4)
The video encoding device 4 according to the present embodiment will be described with reference to FIGS. In the following, the same parts as those already described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 22 is a block diagram showing a configuration of the video encoding device 4 according to the present embodiment. As illustrated in FIG. 22, the moving image encoding device 4 includes an adaptive filter 60 instead of the adaptive filter 44 included in the moving image encoding device 2 according to the first embodiment. The other configuration of the video encoding device 4 is the same as the configuration of the video encoding device 2 according to the first embodiment, and a description thereof will be omitted.

(Adaptive filter 60)
The adaptive filter 60 generates a filtered decoded image P_FL by performing an adaptive filter process on the deblocked decoded image P_DB. The generated filtered decoded image P_FL is stored in the buffer memory 24. The adaptive filter 60 also supplies various types of adaptive filter information used for the filter processing to the variable length code encoding unit 22 as filter parameters FP. The variable length code encoding unit 22 encodes the filter parameter FP as a part of the encoded data # 3.

  FIG. 23 is a block diagram showing the configuration of the adaptive filter 60. As shown in FIG. 23, the adaptive filter 60 includes a filter parameter determination unit 61 and an adaptive filter unit 62.

(Filter parameter determination unit 61)
The filter parameter determination unit 61 determines luminance filter information, color difference filter information, and filter on / off information, and supplies the information to the adaptive filter unit 62 and the variable length code encoding unit 22. As illustrated in FIG. 24, the filter parameter determination unit 61 includes an on / off information determination unit 611 and a filter information determination unit 612.

(Filter information determination unit 612)
The filter information determination unit 612 determines luminance filter information and color difference filter information from the deblocked decoded image P_DB and the moving image # 10. A filter coefficient group is calculated so that the square error between the deblocked decoded image P_DB and the encoding target image (moving image # 10) is minimized. Luminance filter information and chrominance filter information are determined based on an encoding cost that can be calculated by comparing an image subjected to adaptive filter processing and an encoding target image.

(On / off information determination unit 611)
The on / off information determination unit 611 determines an on / off flag using the filter coefficient group determined by the filter information determination unit 612. When the control pattern is 1, the on / off information determination unit 611 determines an on / off flag alf_cu_flag applied to the adaptive filter processing of the luminance component Y. When the control pattern is 2, the on / off information determination unit 611 determines an on / off flag alf_cu_flag for adaptive filter processing and a flag alf_cu_control_flag_chroma that specifies whether to apply the on / off flag alf_cu_flag to the color difference adaptive filter. In the case of the control pattern 3, the on / off information determination unit 611 determines the on / off flag alf_cu_flag_luma of the luminance component Y and the on / off flag alf_cu_flag_chroma of the color difference component Cr and the color difference component Cb. When the control pattern is 4, the on / off information determination unit 611 determines the luminance component Y, the color difference component Cr, the color difference component Cb, and the on / off flags alf_cu_flag_luma, alf_cu_flag_cr, and alf_cu_flag_cb that are applied to each adaptive filter process.

  The on / off flag is compared with the case where the filter processing is performed using the filter coefficient group determined by the filter information determination unit 612 and the case where the filter processing is not performed. It is determined to be on when the square error with the image to be encoded is small, and off in other cases. In particular, in the case of the control pattern 2, when the on / off flag is determined for the luminance component Y and then the on / off of the color difference component is controlled using the on / off flag, alf_cu_flag_chroma is set to 1 when the square error becomes small. In other cases, it is determined to be 0. In the case of the control pattern 3, in the target unit region, the sum of the square error between the encoding target image and the filtered decoded image in the color difference component Cb and the square error between the encoding target image and the filtered decoded image in the color difference component Cr. Is determined to be on when it is smaller than the sum of the square errors of the encoding target image and the decoded image before the filter, and is determined to be off otherwise. In the control pattern 2 as well, an optimal on / off flag may be determined by simultaneously handling a plurality of components. Specifically, in the target unit area, the square error between the encoding target image and the filtered decoded image in the luminance component Y, and the square error between the encoding target image and the filtered decoded image in the color difference component Cb and the color difference component Cr. Is determined to be on when it is smaller than the sum of the square errors of the encoding target image and the decoded image before the filter, and is determined to be off otherwise.

(Color difference component control unit)
In the present embodiment, control by the common on / off flag alf_cu_flag and the luminance component Y by alf_cu_flag_luma is performed in the CU unit of the coding unit. Performed in units of LCU. If the encoding unit of the on / off flag is reduced, the image quality after filtering can be improved, but the code amount of the on / off flag is increased. The encoding unit of the on / off flag needs to be determined appropriately. When the color difference sampling is 4: 2: 0 or the like, the resolution of the color difference component is smaller than the resolution of the luminance component, so the effect of improving the image quality obtained using the adaptive filter is also small. If the color difference on / off flag is encoded using the same unit as the luminance, the on / off flag becomes relatively large, which is not appropriate in terms of encoding efficiency. For this reason, it is appropriate to control the color difference in units larger than the luminance control. Further, since it is preferable that the decoding process can be performed in units of LCUs, it is appropriate to encode the on / off flag in units of LCUs or less. For this reason, in this embodiment, the LCU unit is used as the unit of the color difference on / off flag, thereby reducing the number of on / off flags and improving the coding efficiency as a whole.

(Adaptive filter unit 62)
The adaptive filter unit 62 performs an adaptive filter process using the filter parameter FP from the filter parameter determination unit 61 on the deblocked decoded image P_DB to generate a filtered decoded image P_FL. In the processing of the adaptive filter unit 62, the adaptive filter processing of the luminance component Y is the same as the luminance adaptive filter unit 33, and the adaptive filter processing of the color difference component Cr and the color difference component Cb is the same as the color difference adaptive filter unit 32. The description is omitted here.

  In the configuration of the second embodiment described above, the on / off control of the adaptive filter processing of the coding unit can be commonly performed in two or more components of the luminance component Y, the color difference component Cr, and the color difference component Cb. Specifically, the code amount of the on / off flag can be reduced by using a common on / off flag in the adaptive filter processing of the luminance component Y and the adaptive filter processing of the color difference component. In addition, the code amount of the on / off flag can be reduced by using a common on / off flag in a plurality of color difference component adaptive filters. In general, since the color difference component Cr and the color difference component Cb have a lower resolution than the luminance component Y, even if the on / off control of the color difference component is performed in LCU units in a wider range than the CU unit, the influence on image quality degradation is small. . Further, when the on / off control of the color difference component Cr and the color difference component Cb is performed in units of LCUs, the total number of on / off flags used for the color difference component Cr and the color difference component Cb can be reduced, so that the code amount can be reduced.

1 Video decoding device (decoding device)
DESCRIPTION OF SYMBOLS 11 Variable length code decoding part 12 Motion vector decompression | restoration part 13 Inverse quantization and inverse transformation part 14 Adder 15, 24 Buffer memory 16 Inter prediction image generation part 17 Intra prediction image generation part 18 Prediction method determination part 19, 43 Deblocking filter 30, 44, 50, 60 Adaptive filter 31 Color difference adaptive filter information decoding unit (filter information decoding means)
311 Color difference adaptive filter coefficient deriving unit 32, 441, 52 Color difference adaptive filter unit 321, 321a, 321b, 521a, 521b, 531 Switch unit 322, 522 Cr filter processing unit (filter means)
323,523 Cb filter processing section (filter means)
33, 444, 53 Luminance adaptive filter unit 442 Color difference filter information determination unit (filter information determination means)
4421 Color difference filter coefficient calculation unit 4422 Color difference filter coefficient determination unit 443, 52, 62 Adaptive filter unit (filter means)
51 Adaptive filter information restoration unit (filter information decoding means)
511 On-off information restoration unit 512 Filter information restoration unit 532 Y filter processing unit (filter means)
2,4 video encoding device (encoding device)
21 Transformer / Quantizer 22 Variable length code coder (variable length coding means)
23 Inverse quantization / inverse conversion unit 25 Intra prediction image generation unit 26 Inter prediction image generation unit 27 Motion vector detection unit 28 Prediction method control unit 29 Motion vector redundancy deletion unit 61 Filter parameter determination unit (filter information determination unit)
611 On-off information determination unit 612 Filter information determination unit

Claims (18)

A moving image decoding apparatus for decoding an image having a plurality of color components, information for specifying a color component to be filtered, and filter information decoding means for decoding a filter coefficient group;
Moving image decoding comprising: filter means for performing filter processing on each color component to be processed using the filter coefficient group decoded by the filter information decoding means and information designating the color component apparatus.   The filter information decoding means adds at least one filter coefficient of a filter coefficient group of a certain color component to a filter coefficient of a filter coefficient group of another color component that has already been decoded and a value decoded from encoded data Alternatively, the moving picture decoding apparatus according to claim 1, wherein decoding is performed using a subtraction value.   The filter information decoding means decodes a filter coefficient group used for filter processing for a plurality of color components, and decodes without using a filter coefficient group of another color component that has already been decoded, and an already decoded One or more subordinate filter coefficient groups to be decoded using the filter coefficient groups of the other color components, the assignment flag indicating the color component to be filtered using the independent filter coefficient group, and the filter The moving image decoding apparatus according to claim 2, wherein the means performs a filter process using a filter coefficient group derived according to the allocation flag. A moving image decoding apparatus for decoding an input image having a plurality of color components,
Filter information decoding means for decoding filter on / off information including one or more on / off flags for designating whether or not to perform filter processing in each of a plurality of unit regions constituting the input image, and a filter coefficient group;
A moving picture decoding apparatus comprising: a filter unit that performs filter processing of a color component for each unit region with reference to the filter on / off information.   With reference to one on / off flag in the filter on / off information, by determining on / off of the unit region existing at the same position of two or more color components of the input image, the two or more color components 5. The moving picture decoding apparatus according to claim 4, wherein the filtering process is commonly controlled. The filter information decoding means decodes a selection flag for selecting whether an on / off flag included in the filter on / off information is used as an on / off flag for a specific color component or as a common on / off flag for a plurality of color components. The moving picture decoding apparatus according to claim 5, wherein: The color component is composed of at least a luminance component and a color difference component,
Whether the filter information decoding unit uses, as the selection flag, one filter on / off flag included in the filter on / off information as an on / off flag of a luminance component or an on / off flag common to a luminance component and a color difference component The moving picture decoding apparatus according to claim 6, wherein a flag for selecting is decoded.   The filter information decoding means is a control pattern 1 that uses an on / off flag only for a luminance component, a control pattern 2 that uses a common on / off flag for a luminance component and a color difference component, or a control that uses a common on / off flag for a plurality of color difference components. A selection mode indicating at least one of pattern 3 or control pattern 4 using an independent on / off flag with a luminance component and a plurality of color difference components is decoded, and 1 when the selection mode indicates control pattern 1 or control pattern 2 One on / off flag is decoded, two on / off flags are decoded when the selection mode indicates a control pattern 2, and three on / off flags are decoded when the selection mode indicates a control pattern 4 The moving picture decoding apparatus according to claim 6. An encoding device that encodes an image having a plurality of color components,
Information specifying a color component to be subjected to filter processing, determining a filter coefficient group used for the filter processing, filter information determining means for determining filter information to be encoded as a filter parameter,
A moving image comprising: filter means for performing filter processing on each color component to be processed using the filter coefficient group determined by the filter information determination means; and variable length encoding means for encoding the filter information. Image encoding device.   The filter information determining means determines at least one element of filter information based on a difference value between a filter coefficient of one determined filter coefficient group and a filter coefficient of another color component filter coefficient group. The moving picture encoding apparatus according to claim 9. The filter information determining means determines one independent filter coefficient group to be encoded without using filter coefficient groups of other color components, and a filter coefficient group to be encoded using filter coefficient groups of other color components. The allocation flag indicating a color component to be filtered is further determined using an independent filter coefficient group, and the variable-length encoding unit encodes the allocation flag. Video encoding device. A moving image encoding device for encoding an input image having a plurality of color components,
In each of a plurality of unit areas constituting the input image, filter on / off information for specifying whether or not to perform filter processing, filter information determination means for determining filter information to be encoded with filter coefficient groups used for filter processing,
Filter means for performing filter processing for each unit region with reference to the filter on / off information and a filter coefficient group, and variable length coding means for encoding a filter parameter including the filter on / off information and filter information. A moving image encoding device.   The moving image encoding device is a moving image encoding device that encodes an image having two or more color components, and determines whether the unit area existing at the same position of the two or more color components is on or off. 13. The moving picture coding apparatus according to claim 12, further comprising filter information determination means for determining an on / off flag.   The filter information determining means determines a selection flag for selecting whether to use the already encoded filter on / off information as an on / off flag for a specific color component or as a common on / off flag for a plurality of color components. The moving picture coding apparatus according to claim 13, wherein The color component is composed of at least a luminance component and a color difference component,
The filter information determination means determines a flag for selecting whether the already-decoded filter on / off information is used as a luminance component on / off flag or a common on / off flag for a luminance component and a color difference component. The moving picture encoding apparatus according to claim 14, characterized in that:   The filter information determining means is a control pattern 1 that uses an on / off flag only for a luminance component, a control pattern 2 that uses a common on / off flag for a luminance component and a color difference component, or a control that uses a common on / off flag for a plurality of color difference components. A selection mode indicating at least one of pattern 3 or a control pattern 4 using an independent on / off flag that is independent of a luminance component and a plurality of color difference components is determined, and 1 when the selection mode indicates control pattern 1 or control pattern 2 2. On-off flags are determined, two on-off flags are determined when the selection mode indicates a control pattern 2, and three on-off flags are determined when the selection mode indicates a control pattern 4. Item 15. The moving image encoding device according to Item 14. Information for designating color components to be filtered, and filter information decoding means for decoding a filter coefficient group;
Moving image decoding comprising: filter means for performing filter processing on each color component to be processed using the filter coefficient group decoded by the filter information decoding means and information designating the color component A data structure of encoded data used for filtering processing of an image having a plurality of color components, which is referred to by the apparatus, and includes information specifying the color components used by the filter means and a filter coefficient group A data structure of encoded data characterized by the above. Filter information decoding means for decoding filter on / off information including one or more on / off flags for designating whether or not to perform filter processing in each of a plurality of unit regions constituting the input image, and a filter coefficient group;
Filtering processing of an image having a plurality of color components, which is referred to by a moving image decoding apparatus, comprising: filter means for performing filtering processing of color components for each unit region with reference to the filter on / off information A data structure of encoded data used in the above-mentioned, which includes filter on / off information and a filter coefficient group used by the filter means.