JP2007158770A - Video decoding device, and video decoding program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video decoding device and video decoding program which can reduce coding distortion of a decoded moving image signal while maintaining high-definition, in consideration of the requirement for an image improvement method independent of coding systems. <P>SOLUTION: The video decoding device for reducing coding distortion has: a decoder 1 for decoding an encoded moving image signal and outputting a decoded moving image signal and motion vector information; a similarity calculating part 6 for receiving an output processing object picture and one reference picture or more that are temporally adjacent to the processing object picture, using the motion vector information to segment pixel blocks respectively from the processing object picture and the reference picture, and outputting the pixel blocks; an averaging part 8 for preparing an averaged pixel block by performing temporal averaging processing that uses the pixel block of the processing object picture and the pixel block of the reference picture and outputting the averaged pixel block; and a block replacing part 10 and 11 for replacing the pixel block of the processing object picture with the averaged pixel block. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a video decoding device and a video decoding program, and more particularly to a video decoding device and a video decoding program that decode an encoded moving image signal and reduce encoding distortion from the decoded moving image signal.

  For example, typical distortions that occur with lossy encoding of moving images include block distortion and mosquito noise. Block distortion is distortion in which signal discontinuity occurs between adjacent blocks after decoding by dividing an image into small blocks and independently performing quantization processing, and a block-like pattern appears.

  Mosquito noise is a distortion in which a ringing pattern appears as if a mosquito is flying at the edge of an image due to insufficient high frequency components in the decoded image due to encoding processing that reduces image high frequency components.

  Conventionally, as a technique for improving the coding distortion, a pre-filter process for performing a filter process on a moving image signal before encoding and a post-filter for performing a filter process on a decoded video signal are known. There is processing.

  In the prefiltering process, high-frequency components that cause coding distortion are removed in advance by performing low-pass filter processing on a moving image before coding (see, for example, Non-Patent Document 1). .

  The post-filtering process smoothes the coding distortion by applying a low-pass filter process to the decoded moving image signal in which the coding distortion has occurred (for example, non-patent document 2). reference).

Post-filtering is performed using AVC / H. It is also used as a deblocking filter in the H.264 encoding method. This deblocking filter smoothes block distortion by performing low-pass filter processing at the block boundary of the decoded moving image, making it visually inconspicuous.
Takeshi Miyamoto and Aiichiro Miyako, “A Study on Pre-Filter for Image Quality Improvement of Video Coding”, 1997 IEICE General Conference, D-11-1 Takeshi Mogi, “Reduction of DCT coding distortion by adaptive smoothing”, 2000 IEICE General Conference, D-11-28

  Among the conventional methods described above, the encoding distortion reduction method by the prefiltering process uniformly applies smoothing processing to the image edge component of the input image, etc. As a result, the high definition of the image was lost, and the image quality was reduced. Although adaptive processing such as changing the filter coefficient based on the static characteristics of the input image and the local properties in the screen has been attempted, there is no definitive method that can achieve the same effect for all images. .

  In addition, in the conventional encoding distortion reduction method using post-filtering, not only the edge component due to the encoding distortion such as block distortion but also the original edge component of the image is subjected to the smoothing processing, so that the original contour of the image can be obtained. Was also blurred, and the image quality was reduced.

  On the other hand, while trying to smooth only the edge component due to coding distortion while retaining the original edge component of the image, in general, the original edge component of the image is distinguished from the edge component due to the coding distortion. It is difficult to set a threshold value for this purpose.

  Regarding post-filtering, AVC / H. Some encoding methods use a deblocking filter such as the H.264 encoding method, while other encoding methods do not use a deblocking filter such as the MPEG-2 encoding method. In the presence of a large number of moving image encoding methods, there has been a high demand for an image quality improvement method that does not depend on the encoding method.

  The present invention has been made in view of the above points, and an object thereof is to provide a video decoding apparatus and a video decoding program capable of reducing encoding distortion from a decoded moving image signal while maintaining high definition.

  In order to solve the above-described problems, the present invention is a video decoding device that reduces coding distortion from a decoded video signal, and outputs the decoded video signal and motion vector information by decoding the encoded video signal. And a processing target screen output from the decoded moving image signal and one or more reference screens temporally adjacent to the processing target screen, and using the motion vector information, the processing target screen and Perform a time averaging process using the similarity calculation unit that cuts out and outputs each pixel block from the reference screen, and the pixel block of the processing target screen output from the similarity calculation unit and the pixel block of the reference screen An averaged pixel block that generates an averaged pixel block and outputs the averaged pixel block, and a block that replaces the averaged pixel block with a pixel block of the processing target screen. And having a click replacement unit.

  The present invention also includes a step of decoding the encoded video signal and outputting the decoded video signal and motion vector information to a computer that functions as a video decoding device that reduces encoding distortion from the decoded video signal. , A processing target screen output from the decoded video signal and one or more reference screens temporally adjacent to the processing target screen are input, and each of the processing target screen and the reference screen is used using the motion vector information. A pixel block is cut out and output, and an averaged pixel block is generated by performing time averaging processing using the output pixel block of the processing target screen and the pixel block of the reference screen, and the averaged pixel Outputting a block; and replacing the averaged pixel block with a pixel block of the processing target screen. Characterized in that it is a video decoding program for.

  The present invention is applied to a decoded moving image signal in which coding distortion has occurred, uses a plurality of reference screens on the same time axis including a processing target screen, averages a plurality of pixel blocks, and By replacing it, coding distortion is reduced.

  As described above, according to the present invention, it is possible to provide a video decoding apparatus and a video decoding program capable of reducing encoding distortion from a decoded moving image signal while maintaining high definition.

  Next, the best mode for carrying out the present invention will be described based on the following embodiments with reference to the drawings. The present invention relates to image quality improvement of an encoded moving image, and relates to image processing for reducing encoding distortion using decoded motion vector information.

  The present invention uses the temporal continuity or similarity of moving images and reduces coding distortion by temporal smoothing processing on the decoded moving images. The present invention adaptively weights the subject according to the spatial position of the subject and the degree of temporal similarity, thereby reducing coding distortion while maintaining high definition of the image.

  First, in order to facilitate understanding of the present invention, an outline of the present invention will be described with reference to the image diagrams of FIGS. The image diagrams of FIGS. 1 to 5 show an example of a reference screen. In the following description, the numerical value indicated by M indicates the interval between the P picture and the P picture or the interval between the P picture and the I picture.

  For example, if M = 1, the coded picture group is represented by a structure as shown in FIG. If M = 3, the coded picture group is represented by a structure as shown in FIG. FIG. 6 is an image diagram of an example showing a GOP (Group Of Pictures) configuration with M = 1. FIG. 7 is an image diagram of an example showing a GOP configuration with M = 3.

  FIG. 1 is an image diagram of an example showing an outline of processing of a P picture when M = 1. The upper part of FIG. 1 represents the input decoded video signal. The decoded video signal in FIG. 1 is input in the order of screens 100, 101, 102, 103 and 104.

  In the present invention, the motion vector of the pixel block B on the processing target screen 102 is used, and the motion vector is extrapolated to obtain the pixel block C on the screen 103 indicated. In the present invention, a weighted averaging process based on the similarity between the pixel block B and the pixel block C is performed to create a pixel block B ′ and replace it with the pixel block B on the processing target screen 102. By performing this process for all the pixel blocks of the processing target screen 102, an improved moving image signal with improved image quality can be obtained in the present invention.

  The lower part of FIG. 1 represents an improved moving image signal in which image quality is improved by reducing coding distortion. The improved moving image signal of FIG. 1 is output in the order of screens 110, 111, 112, 113, and 114. The screen 112 is obtained by replacing the pixel block B of the processing target screen 102 with the pixel block B ′.

  Similarly to the processing target screen 102, the present invention uses the motion vector of the block E of the processing target screen 103 and extrapolates the motion vector to obtain the pixel block F of the screen 104 indicated. In the present invention, a weighted averaging process based on the similarity between the pixel block E on the processing target screen 103 and the pixel block F on the screen 104 is performed to create a pixel block E ′, and the pixel block E on the processing target screen 103 Has been replaced.

  FIG. 2 is an image diagram of an example showing an outline of processing of an I picture when M = 1. The upper part of FIG. 2 represents the input decoded video signal. The decoded video signal in FIG. 2 is input in the order of screens 120, 121, 122, 123, and 124.

  In the present invention, the pixel block C of the processing target screen 122 is obtained by extrapolating the motion vector of the pixel block B of the screen 121. In the present invention, a weighted averaging process based on the similarity between the pixel block B and the pixel block C is performed to create a pixel block C ′ and replace it with the pixel block C on the processing target screen 122. By performing this process on all the pixel blocks of the screen 121 that is a P picture one past when viewed from the processing target screen 122, an improved moving image signal with improved image quality can be obtained in the present invention.

  The lower part of FIG. 2 represents an improved moving image signal in which the image quality is improved by reducing the coding distortion. The improved moving image signal of FIG. 2 is output in the order of the screens 130, 131, 132, 133 and 134. The screen 132 is obtained by replacing the pixel block C of the processing target screen 122 with the pixel block C ′.

  In this case, not all pixels are necessarily replaced in the I picture that is the processing target screen 122. In an actual video, there is no practical problem because the motion vector hardly concentrates on a certain point on the screen.

  FIG. 3 is an image diagram of an example showing an outline of P picture processing when M = 3. The upper part of FIG. 3 represents the input decoded video signal. The decoded video signal in FIG. 3 is input in the order of screens 140, 141, 142, 143, and 144.

  In the present invention, the motion vector of the pixel block C on the processing target screen 143 is used, and the pixel block B on the screen 142 indicated by the motion vector is obtained. In the present invention, the weighted averaging process based on the similarity between the pixel block B and the pixel block C is performed to create the pixel block C ′ and replace it with the pixel block C on the processing target screen 143. By performing this process for all the pixel blocks on the processing target screen 143, an improved moving image signal with improved image quality can be obtained in the present invention.

  The lower part of FIG. 3 represents an improved moving image signal in which image quality is improved by reducing coding distortion. The improved moving image signal of FIG. 3 is output in the order of screens 150, 151, 152, 153, and 154. The screen 153 is obtained by replacing the pixel block C of the processing target screen 143 with the pixel block C ′.

  In the present invention, in order to use the most recent picture as possible, the pixel block B of the screen 142 is obtained instead of the screen 141 indicated by the motion vector. If the latest picture is used in this way, it becomes a countermeasure against a scene change or the like.

  FIG. 4 is an image diagram of an example showing an outline of processing of a B picture when M = 3. The upper part of FIG. 4 represents the input decoded video signal. The decoded moving image signal of FIG. 4 is input in the order of screens 160, 161, 162, 163 and 164.

  When M = 3, there are two B pictures in succession. Here, the past B picture (screen 161) is identified as a B1 picture, and the future B picture (screen 162) is identified as a B2 picture.

  When processing a B1 picture, in the present invention, the motion vector of the pixel block B on the processing target screen 161 is used, and the pixel block C on the screen 162 indicated by the motion vector is obtained. In the present invention, a weighted averaging process based on the similarity between the pixel block B and the pixel block C is performed to create a pixel block B ′ and replace it with the pixel block B on the processing target screen 161.

  When processing a B2 picture, in the present invention, the motion vector of the pixel block G on the processing target screen 162 is used, and the pixel block F on the screen 161 indicated by the motion vector is obtained. In the present invention, a weighted averaging process based on the similarity between the pixel block F and the pixel block G is performed to create a pixel block G ′ and replace it with the pixel block G on the processing target screen 162.

  By performing this process for all the pixel blocks of the processing target screen 161 or 162, an improved moving image signal with improved image quality can be obtained in the present invention.

  The lower part of FIG. 4 represents an improved moving image signal in which the encoding distortion is reduced and the image quality is improved. The improved moving image signal of FIG. 4 is output in the order of screens 170, 171, 172, 173, and 174. The screen 171 is obtained by replacing the pixel block B of the processing target screen 161 with the pixel block B ′. Further, the screen 172 is obtained by replacing the pixel block G of the processing target screen 162 with the pixel block G ′.

  FIG. 5 is an image diagram of an example showing an outline of processing of an I picture when M = 3. The upper part of FIG. 5 represents the input decoded video signal. The decoded video signal in FIG. 5 is input in the order of screens 180, 181, 182, 183, and 184.

  In the present invention, the motion vector of the pixel block B on the screen 181 is used, and the pixel block C on the screen 182 and the pixel block D on the processing target screen 183 indicated by the motion vector are obtained. In the present invention, the weighted averaging process based on the similarity between the pixel block C and the pixel block D is performed to create the pixel block D ′ and replace it with the pixel block D on the processing target screen 183.

  By performing this process for all the pixel blocks of the screen 181 that are two B pictures in the past as viewed from the processing target screen 183, an improved moving image signal with improved image quality can be obtained in the present invention.

  The lower part of FIG. 5 represents an improved moving image signal in which the encoding distortion is reduced and the image quality is improved. The improved moving image signal in FIG. 5 is output in the order of screens 190, 191, 192, 193, and 194. The screen 193 is obtained by replacing the pixel block D of the processing target screen 183 with the pixel block D ′.

  In this case, not all the pixels are replaced in the I picture that is the processing target screen 183. In an actual video, there is no practical problem because the motion vector hardly concentrates on a certain point on the screen.

  In addition, in a P picture or a B picture, a motion vector that is rarely used for processing may not exist depending on a pixel block. For example, when a pixel block is an intra block (an intra-screen coding block that does not use a motion vector), there may be no motion vector used for processing. When there is no motion vector used for processing, the above-described calculation processing is not performed in the pixel block.

  However, even if there is no motion vector in the pixel block, in the case of an encoding algorithm that predicts and calculates a motion vector from surrounding motion vectors (for example, using the same motion vector as the motion vector of the left adjacent pixel block) ), Using the calculated motion vector.

  Also, depending on the encoding method, the motion vector may be calculated in units of frames, may be calculated in units of fields, may be calculated in units of sub-blocks obtained by dividing a block, etc. The same processing as that described above may be sequentially performed for each target pixel block size.

  The present invention is applied to a decoded video signal in which coding distortion has occurred. The present invention averages a plurality of pixel blocks having a high similarity in a plurality of pictures on the same time axis including a processing target screen (processing target picture) using the decoded motion vector information, and the pixels of the processing target picture By replacing it with a block, coding distortion can be reduced.

  In the following embodiments, a signal input to the video decoding apparatus of the present invention is an encoded video signal (hereinafter referred to as an encoded stream) that has been inter-screen compressed using a motion vector. To do. For example, an encoded stream that has been inter-screen compressed using a motion vector corresponds to an MPEG-2 or MPEG-4 AVC (H.264) encoded stream.

  FIG. 8 is a block diagram of the first embodiment of the video decoding apparatus according to the present invention. 8 includes a decoder 1, a 1-frame delay unit 2, a 1-frame delay unit 3, a memory 4, a motion vector extrapolation unit 5, a similarity calculation unit 6, a weighting control unit 7, a weighted average unit 8, A switch 9, a block replacement unit 10, a block replacement unit 11, a one-frame delay unit 12, and a switch 13 are included.

  The encoded stream input to the video decoding apparatus according to the present invention is a moving image signal that has been subjected to lossy compression encoding. The encoded stream is input to the decoder 1. The decoder 1 decodes the input encoded stream, and outputs the decoded moving image signal to the 1-frame delay unit 2, the similarity calculation unit 6, and the block replacement unit 10. The decoder 1 outputs the picture type information included in the encoded stream to the 1-frame delay unit 3 and the switch 9. Further, the decoder 1 outputs the motion vector information included in the encoded stream to the memory 4.

  The 1-frame delay unit 2 delays the input decoded video signal by one frame, and then outputs it to the similarity calculation unit 6 and the block replacement unit 11. The 1-frame delay unit 3 delays the input picture type information by one frame and then outputs it to the switch 13.

  The memory 4 sequentially stores the input motion vector information for one frame. The memory 4 stores new motion vector information by pushing out the stored motion vector information if motion vector information is input. The motion vector information pushed out from the memory 4 is input to the motion vector extrapolation unit 5. The motion vector extrapolation unit 5 extrapolates the motion vector included in the input motion vector information, and outputs the extrapolated motion vector to the similarity calculation unit 6.

  The similarity calculation unit 6 receives a decoded moving image signal input from the decoder 1, a decoded moving image signal delayed by one frame input from the 1 frame delay unit 2, and a motion vector extrapolation unit 5. Using the extrapolated motion vector, the similarity is calculated as follows. As shown in FIG. 1, when the processing target screen is a P picture, the similarity calculation unit 6 uses the motion vector of the pixel block of the processing target screen to perform processing with the one future picture. Further, as shown in FIG. 2, when the processing target screen is an I picture, the similarity calculation unit 6 uses a motion vector of a pixel block of one previous picture and performs processing with one previous picture. .

  First, as shown in FIG. 1, a process when the processing target screen is a P picture will be described. The similarity calculation unit 6 uses the motion vector of the pixel block B on the processing target screen 102, and obtains the pixel block C on the reference screen 103 indicated by extrapolating the motion vector.

  The similarity calculation unit 6 obtains the similarity between the pixel block B of the processing target screen 102 and the pixel block C of the reference screen 103 indicated by the extrapolated motion vector. For example, the similarity SML between pixel blocks is calculated using the following equations (1) and (2).

  crti, j represents the pixel value of the pixel block of the processing target screen. ref i, j represents the pixel value of the pixel block of the reference screen. TD represents a temporal distance between the processing target screen and the reference screen.

式（２）は、処理対象画面の画素ブロックの画素値と参照画面の画素ブロックの画素値との差分を画素ブロック単位で加算し、処理対象画面と参照画面との時間的な距離に応じて補正してＳＡＤを算出している。

Equation (2) adds the difference between the pixel value of the pixel block of the processing target screen and the pixel value of the pixel block of the reference screen in units of pixel blocks, and depends on the temporal distance between the processing target screen and the reference screen. The SAD is calculated after correction.

  In SAD, the smaller the value obtained by adding the difference between the pixel value of the pixel block of the processing target screen and the pixel value of the pixel block of the reference screen in units of pixel blocks, the closer the temporal distance between the processing target screen and the reference screen is The smaller the value. In addition, the SAD is a temporal distance between the processing target screen and the reference screen as the value obtained by adding the difference between the pixel value of the pixel block of the processing target screen and the pixel value of the pixel block of the reference screen in units of pixel blocks is larger. The farther is, the larger the value.

  Equation (1) calculates a similarity SML that is the reciprocal of SAD. The similarity SML is such that the smaller the value obtained by adding the difference between the pixel value of the pixel block of the processing target screen and the pixel value of the pixel block of the reference screen in units of pixel blocks, the longer the temporal distance between the processing target screen and the reference screen. The closer it is, the larger the value. In addition, the similarity SML is larger in time between the processing target screen and the reference screen as the value obtained by adding the difference between the pixel value of the pixel block of the processing target screen and the pixel value of the pixel block of the reference screen in units of pixel blocks is larger. The smaller the distance, the smaller the value.

  The similarity calculation unit 6 outputs the image data of the pixel block B of the processing target screen 102 and the pixel block C of the reference screen 103 indicated by the extrapolated motion vector to the weighted average unit 8. Further, the similarity calculation unit 6 uses the block positions of the pixel block B of the processing target screen 102 and the pixel block C of the reference screen 103 indicated by the extrapolated motion vector and the similarity values as detection signals, and the weighting control unit 7 Output to.

  The weight control unit 7 determines the weight of the averaging process performed by the weighted average unit 8 based on the detection information input from the similarity calculation unit 6. The detection information includes the block positions of the pixel block B on the processing target screen 102 and the pixel block C on the reference screen 103 indicated by the extrapolated motion vector, and the similarity value.

  The weighting control unit 7 equalizes the weighted average weighting between the pixel block B of the processing target screen 102 and the pixel block C of the reference screen 103 when the similarity is high, and the pixels of the processing target screen 102 when the similarity is low. A process of increasing the weight for block B is performed.

  However, when the spatial position of the pixel block C on the reference screen 103 is the same as the spatial position of the pixel block B on the processing target screen 102, the weighting control unit 7 sets the weighting on the pixel block B on the processing target screen 102 to 100% ( The averaging process is not performed as wcrt = 1).

  In addition, the weighting control unit 7 determines that the spatial positional relationship with the block distortion boundary at the block position of the pixel block C on the reference screen 103 is the spatial positional relationship with the block distortion boundary at the block position of the pixel block B on the processing target screen 102. If the same, the weighting for the pixel block B on the processing target screen 102 is set to 100% (wcrt = 1) and the averaging process is not performed.

  FIG. 9 is an image diagram showing processing of the weighting control unit. The appearance position of block distortion is fixedly determined by the control of the encoder. For example, in MPEG-2, the block boundary of a pixel block of 8 × 8 size corresponds to the appearance position of block distortion. In FIG. 9, the boundary of block distortion is shown by a lattice pattern. In FIG. 9, a processing target screen is shown on the right side, and a reference screen is shown on the left side. Here, the pixel block of the reference screen indicated by the extrapolated motion vector is referred to as a matching block.

  For example, if the matching block is the pixel block B1, the spatial position of the pixel block A on the processing target screen and the pixel block B1 on the reference screen are the same, and the spatial positional relationship with the boundary of the block distortion is also the same. In this case, the weighting control unit 7 sets the weighting for the pixel block A on the processing target screen to 100% so that the averaging process is not performed as a result.

  Similarly, if the matching block is the pixel block B2, the spatial positions of the pixel block A on the processing target screen and the pixel block B2 on the reference screen are different, but the spatial positional relationship with the block distortion boundary is the same. In this case, the weighting control unit 7 sets the weighting for the pixel block A on the processing target screen to 100% so that the averaging process is not performed as a result.

  However, if the matching block is the pixel block B3, the pixel block A on the processing target screen and the pixel block B3 on the reference screen are different in spatial positional relationship with the block distortion boundary. In this case, the weighting control unit 7 performs weighting based on the similarity value of the pixel block A of the processing target screen and the pixel block B3 of the reference screen (for example, the weighting of the pixel block A of the processing target screen is 50%, the pixel of the reference screen) An averaging process is performed by determining a weight of 50% for the block B3.

  For example, the determination of weighting based on the similarity value is performed using the following equations (3) and (4). wcrt represents the weighting coefficient of the processing target screen. wref represents the weighting coefficient of the reference screen. A and B represent constants. Nref is the number of matching blocks in the reference screen. In this embodiment, Nref = 1.

式（４）は、類似度ＳＭＬに基づき、参照画面の重み付け係数ｗrefを算出している。参照画面の重み付け係数ｗrefは、類似度ＳＭＬが大きいほど、大きな値となる。式（３）は、参照画面の重み付け係数ｗrefに基づき、処理対象画面の重み付け係数ｗcrtを算出している。処理対象画面の重み付け係数ｗcrtは、類似度ＳＭＬが小さいほど、大きな値となる。

Formula (4) calculates the weighting coefficient wref of the reference screen based on the similarity SML. The weighting coefficient wref of the reference screen is larger as the similarity SML is larger. Expression (3) calculates the weighting coefficient wcrt of the processing target screen based on the weighting coefficient wref of the reference screen. The weighting coefficient wcrt of the processing target screen becomes a larger value as the similarity SML is smaller.

  FIG. 10 is a flowchart illustrating an example of processing of the weighting control unit. When detection information including the block position of the matching block and the value of the similarity is input from the similarity calculation unit 6, the weighting control unit 7 proceeds to step S1 and acquires the block position of the matching block from the detection information. To do.

  In step S2, the weight control unit 7 determines whether the spatial position of the matching block is the same as the spatial position of the pixel block B on the processing target screen. That is, the weighting control unit 7 determines whether or not the spatial positions are the same as the pixel block B1 of the reference screen and the pixel block A of the processing target screen in FIG.

  If the spatial position of the matching block is the same as the spatial position of the pixel block B on the processing target screen (YES in S2), the weighting control unit 7 proceeds to step S5 and sets the weighting for the pixel block B on the processing target screen to 100%. The weighting coefficient is determined as follows.

  If the spatial position of the matching block is not the same as the spatial position of the pixel block B on the processing target screen (NO in S2), the weighting control unit 7 proceeds to step S3, and the space from the block distortion boundary at the block position of the matching block It is determined whether the positional relationship is the same as the spatial positional relationship with the block distortion boundary at the block position of the pixel block B on the processing target screen.

  That is, the weighting control unit 7 determines whether or not the spatial positional relationship between the block distortion boundaries is the same as in the pixel block B2 of the reference screen and the pixel block A of the processing target screen in FIG.

  If it is determined that the spatial positional relationship with the boundary of the block distortion is the same (YES in S3), the weighting control unit 7 proceeds to step S5 and performs weighting so that the weighting for the pixel block B on the processing target screen is 100%. Determine the coefficient.

  If it is determined that the spatial positional relationship with the boundary of the block distortion is not the same (NO in S3), the weight control unit 7 proceeds to step S4 and determines a weighting coefficient based on the similarity value. By the processing shown in FIG. 10, the weighting control unit 7 determines a weighting coefficient and outputs it to the weighted average unit 8 as weighting information.

  The weighted average unit 8 receives weight information from the weight control unit 7. The weighted average unit 8 acquires a weighting coefficient from the weighting information. The weighted average unit 8 weights and averages the image data of the pixel block B of the processing target screen 102 and the pixel block C of the reference screen 103 input from the similarity calculation unit 6 using the acquired weighting coefficient. For example, weighted averaging is performed using the following equation (5).

ここで、ａｖｅi,jは平均化された画素ブロックの画素値を表す。加重平均部８は平均化された画素ブロックＢ′を平均化ブロック画像情報としてスイッチ９及びブロック置換部１１に出力する。スイッチ９は、復号器１から入力されるピクチャタイプ情報に基づき、処理対象画面がＩピクチャのときに閉じるように制御される。スイッチ９は、加重平均部８とブロック置換部１０との間に設けられている。したがって、処理対象画面がＰピクチャであるとき、平均化ブロック画像情報はブロック置換部１０に入力されない。

Here, ave i, j represents the pixel value of the averaged pixel block. The weighted average unit 8 outputs the averaged pixel block B ′ to the switch 9 and the block replacement unit 11 as averaged block image information. The switch 9 is controlled to close when the processing target screen is an I picture based on the picture type information input from the decoder 1. The switch 9 is provided between the weighted average unit 8 and the block replacement unit 10. Therefore, when the processing target screen is a P picture, the averaged block image information is not input to the block replacement unit 10.

  The block replacement unit 11 acquires an averaged pixel block B ′ from the input averaged block image information. The block replacement unit 11 replaces the averaged pixel block B ′ with the pixel block B of the processing target screen 102 input from the 1-frame delay unit 2. By performing the above processing for all the pixel blocks of the processing target screen 102, the present invention outputs an improved moving image signal with improved image quality to the switch 13.

  The switch 13 is controlled based on the picture type information input from the decoder 1 through the 1-frame delay unit 3 so that the improved moving image signal from the block replacement unit 11 is output when the processing target screen is a P picture. Is done. Therefore, when the processing target screen is a P picture, the switch 13 can output an improved moving image signal with improved image quality.

  Next, as shown in FIG. 2, a process when the processing target screen is an I picture will be described. The similarity calculation unit 6 uses the motion vector of the pixel block B of the screen 121, which is the previous picture of the processing target screen 122, and extrapolates the motion vector to indicate the pixel block C of the processing target screen 122. Get.

  The similarity calculation unit 6 obtains the similarity between the pixel block C on the processing target screen 122 and the pixel block B on the reference screen 121 indicated by the extrapolated motion vector. For example, the similarity SML between pixel blocks is calculated using the above equations (1) and (2).

  The similarity calculation unit 6 outputs the image data of the pixel block C on the processing target screen 122 and the pixel block B on the reference screen 121 indicated by the extrapolated motion vector to the weighted average unit 8. In addition, the similarity calculation unit 6 uses the block positions of the pixel block C on the processing target screen 122 and the pixel block B on the reference screen 121 indicated by the extrapolated motion vector and the similarity value as detection signals, and the weighting control unit 7 Output to.

  Based on the detection information input from the similarity calculation unit 6, the weighting control unit 7 determines the weighting coefficient of the averaging process performed by the weighted average unit 8 as described above, and outputs the weighting information to the weighted average unit 8 as weighting information.

  The weighted average unit 8 obtains a weighting coefficient from the input weighting information, and using the weighting coefficient, the pixel block C of the processing target screen 122 and the pixel block B of the reference screen 121 input from the similarity calculation unit 6. The image data is weighted and averaged. For example, weighted averaging is performed using the above equation (5).

  The weighted average unit 8 outputs the averaged pixel block C ′ to the switch 9 and the block replacement unit 11 as averaged block image information. The switch 9 is controlled to close when the processing target screen is an I picture based on the picture type information input from the decoder 1. The switch 9 is provided between the weighted average unit 8 and the block replacement unit 10. Therefore, when the processing target screen is an I picture, the averaged block image information is input to the block replacement unit 10.

  The block replacement unit 10 acquires an averaged pixel block C ′ from the input averaged block image information. The block replacement unit 10 replaces the pixel block C of the processing target screen 122 input from the decoder 1 with the averaged pixel block C ′ of the processing target screen 122. By performing the above processing for all the pixel blocks on the processing target screen 122, the present invention outputs an improved moving image signal with improved image quality to the one-frame delay unit 12.

  The 1-frame delay unit 12 delays the input improved moving image signal by one frame, and then outputs it to the switch 13. Based on the picture type information input from the decoder 1 through the 1-frame delay unit 3, the switch 13 outputs the improved moving image signal from the 1-frame delay unit 12 when the processing target screen is an I picture. Be controlled. Therefore, when the processing target screen is an I picture, the switch 13 can output an improved moving image signal with improved image quality.

  In the video decoding apparatus according to the present invention, the similarity between the pixel block of the processing target screen and the pixel block of the reference screen indicated by the extrapolated motion vector is obtained again. The reason why the similarity is calculated again with a motion vector generated by extrapolation instead of the motion vector used at the time of encoding is as follows.

  If the pixel block to be encoded using the motion vector (MV) is CBi, j and the pixel block specified by the motion vector is RBi, j, the encoding is performed with respect to Equation (6).

CBi, j-RBi, j = DBi, j (6)
Decoding is performed by adding the decoded difference image dDBi, j to the already decoded pixel block dRBi, j as shown in Equation (7).

dRBi, j-dDBi, j = dCBi, j (7)
That is, when the time averaging process between pixel blocks is performed using the motion vector at the time of encoding, the following equation (8) is obtained in the case of a simple average divided by two.

AVEi, j = (dRBi, j + dCBi, j) / 2 = (2dRBi, j + dDBi, j) / 2 = dRBi, j + dDBi, j / 2 (8)
Eventually, the difference image component dDBi, j, which is a high image quality component, is added to the reference image pixel block dRBi, j only at a half level. This means that an image is almost made up of motion vectors, and the image quality deteriorates because the difference image is not sent so much. Therefore, in the present invention, the image quality improvement processing is performed not by the motion vector at the time of encoding but by the motion vector newly obtained by extrapolating the motion vector.

  FIG. 11 is an image diagram illustrating an example of pixel block cutout. In this invention, it is a figure which shows that the reduction effect of an encoding distortion is acquired more by cutting out the pixel block of a process target screen and a reference screen larger than the block size at the time of an encoding, respectively. This is because the block distortion is a distortion in which a pixel block used for orthogonal transformation or a pixel block used for motion compensation is visualized after decoding.

  For example, when the motion compensation block size at the time of encoding is 16 × 16, the block size used for the processing is, for example, 17 × 17 as shown in FIG. Since block division is determined in advance by the encoding method, block cutout performed by the video decoding apparatus according to the present invention results in overlapping pixel blocks.

  At this time, one pixel along the pixel block boundary is overlapped and the time averaging process is performed, but as a result, the process is focused on the block boundary where the block distortion occurs, and the correction is performed. Work more advantageously.

  FIG. 11 is an example, and for example, it is possible to overlap only in the horizontal direction. In practice, horizontal block boundaries are more distorted than vertical block boundaries. This is due to the characteristics of the camera and the display device, but especially in encoding, field cut-out DCT is also used in the vertical direction. Therefore, when the field blocks are merged into frame blocks, the vertical block boundaries are This is because it is more blurred than in the horizontal direction.

  According to the first embodiment, with respect to the P picture and I picture when M = 1, it is possible to reduce the coding distortion while maintaining high definition and to obtain an improved moving image signal with improved image quality.

  FIG. 12 is a block diagram of a second embodiment of the video decoding apparatus according to the present invention. 12 includes a decoder 21, a 1-frame delay unit 22, a 2-frame delay unit 23, a 1-frame delay unit 24, a 3-frame delay unit 25, a 1-frame delay unit 26, a switch 27, a switch 28, and a picture discrimination. A unit 29, a motion vector extrapolation unit 30, a similarity calculation unit 31, a weighting control unit 32, a weighted average unit 33, and a block replacement unit 34.

  The encoded stream is input to the decoder 21. The decoder 21 decodes the input encoded stream and outputs the decoded moving image signal to the 1-frame delay unit 22, the 2-frame delay unit 23, and the switch 28. Further, the decoder 21 outputs the picture type information included in the encoded stream to the 1-frame delay unit 24. Further, the decoder 21 outputs the motion vector information included in the encoded stream to the 3-frame delay unit 25 and the 1-frame delay unit 26.

  The 1-frame delay unit 22 delays the input decoded moving image signal by one frame, and then outputs it to the similarity calculation unit 31 and the block replacement unit 34. The 2-frame delay unit 23 delays the input decoded video signal by one frame, and then outputs the delayed signal to the switch 28.

  The one-frame delay unit 24 delays the input picture type information by one frame, and then outputs it to the switch 27, the picture determination unit 29, and the block replacement unit 34. The 3-frame delay unit 25 delays the input motion vector information by 3 frames, and then outputs it to the switch 27. The 1-frame delay unit 26 delays the input motion vector information by one frame, and then outputs it to the switch 27.

  Based on the picture type information input from the 1-frame delay unit 24, the switch 27 outputs the motion vector information from the 3-frame delay unit 25 to the motion vector extrapolation unit 30 when the processing target screen is an I picture. Control is performed so that the motion vector information from the 1-frame delay unit 26 is output to the motion vector extrapolation unit 30 when the processing target screen is other than the I picture.

  Based on the picture type information input from the 1-frame delay unit 24, the picture determination unit 29 determines whether or not it is a past B1 picture among two consecutive B pictures. The picture discriminating unit 29 discriminates that the B picture is a B picture immediately after an I picture or a P picture, for example. The picture discrimination unit 29 outputs a discrimination result indicating whether or not it is a B1 picture to the switch 28.

  Based on the determination result indicating whether or not the B1 picture is input from the picture determination unit 29, the switch 28 receives the decoded moving image signal from the decoder 21 when the processing target screen is the B1 picture. The decoded moving image signal from the 2-frame delay unit 23 is controlled to be output to the similarity calculation unit 31 when the processing target screen is other than the B1 picture.

  The motion vector information output from the switch 27 is input to the motion vector extrapolation unit 30. The motion vector extrapolation unit 30 extrapolates the motion vector included in the input motion vector information, and outputs the extrapolated motion vector to the similarity calculation unit 31.

  The similarity calculation unit 31 receives the decoded moving image signal input from the decoder 21 via the switch 28, the decoded moving image signal delayed by one frame input from the one frame delay unit 22, and the two frame delay unit 23. Using the decoded video signal delayed by two frames input via the switch 28 and the extrapolated motion vector input from the motion vector extrapolation unit 30, the similarity is calculated as follows.

  As shown in FIG. 3, when the processing target screen is a P picture, the similarity calculation unit 31 uses the motion vector of the pixel block of the processing target screen to perform processing with the previous B1 picture. Also, as shown in FIG. 4, when the processing target screen is a B1 picture, the similarity calculation unit 31 uses a motion vector in the future direction of the pixel block of the processing target screen to perform processing between one future B2 picture. To do.

  In addition, as shown in FIG. 4, when the processing target screen is a B2 picture, the similarity calculation unit 31 uses a motion vector in the past direction of the pixel block of the processing target screen to process between the previous B1 pictures. To do. Further, as shown in FIG. 5, when the processing target screen is an I picture, the similarity calculation unit 31 uses the motion vector in the future direction of the pixel block of the two past B1 pictures, and Process between.

  First, as shown in FIG. 3, processing when the processing target screen is a P picture will be described. The similarity calculation unit 31 uses the motion vector of the pixel block C on the processing target screen 143 to obtain the pixel block B on the reference screen 142 indicated by the motion vector.

  The similarity calculation unit 31 obtains the similarity between the pixel block C on the processing target screen 143 and the pixel block B on the reference screen 142 indicated by the extrapolated motion vector, as in the first embodiment.

  The similarity calculation unit 31 outputs the image data of the pixel block C on the processing target screen 143 and the pixel block B on the reference screen 142 indicated by the extrapolated motion vector to the weighted average unit 33. Further, the similarity calculation unit 31 uses the block positions of the pixel block C on the processing target screen 143 and the pixel block B on the reference screen 142 indicated by the extrapolated motion vector and the similarity value as a detection signal, and the weighting control unit 32. Output to.

  Based on the detection information input from the similarity calculation unit 31, the weighting control unit 32 determines the weighting coefficient for the averaging process performed by the weighted average unit 33 as described above, and outputs the weighting information to the weighted average unit 33 as weighting information.

  The weighted average unit 33 acquires a weighting coefficient from the input weighting information, and uses the weighting coefficient to input the pixel block C of the processing target screen 143 and the pixel block B of the reference screen 142 input from the similarity calculation unit 31. The image data is weighted and averaged. For example, weighted averaging is performed using the following equation (5).

  The weighted average unit 33 outputs the averaged pixel block C ′ to the block replacement unit 34 as averaged block image information. The block replacement unit 34 acquires the averaged pixel block C ′ from the input averaged block image information. The block replacement unit 34 replaces the averaged pixel block C ′ with the pixel block C of the processing target screen 143 input from the one-frame delay unit 22 and outputs the result. By performing the above processing for all the pixel blocks of the processing target screen 143, the present invention can output an improved moving image signal with improved image quality.

  Next, as shown in FIG. 4, processing when the processing target screen is a B1 picture will be described. The similarity calculation unit 31 uses the motion vector in the future direction of the pixel block B on the processing target screen 161 to obtain the pixel block C on the reference screen 162 of the one future pointed to by the motion vector.

  The similarity calculation unit 31 obtains the similarity between the pixel block B on the processing target screen 161 and the pixel block C on the reference screen 162. Note that the processing after obtaining the similarity is the same as the processing when the processing target screen is a P picture, and thus description thereof is omitted.

  Next, as shown in FIG. 4, a process when the processing target screen is a B2 picture will be described. The similarity calculation unit 31 uses the past direction motion vector of the pixel block G on the processing target screen 162 to obtain the pixel block F on the reference screen 161 of the past pointed to by the motion vector.

  The similarity calculation unit 31 obtains the similarity between the pixel block G on the processing target screen 162 and the pixel block F on the reference screen 161. Note that the processing after obtaining the similarity is the same as the processing when the processing target screen is a P picture, and thus description thereof is omitted.

  Next, as shown in FIG. 5, a process when the processing target screen is an I picture will be described. The similarity calculation unit 31 uses the motion vector in the future direction of the pixel block B of the screen 181 that is the two past B1 pictures of the processing target screen 183, and extrapolates the motion vector to indicate the past one A pixel block C on the screen 182 and a pixel block D on the processing target screen 183 that are B2 pictures are obtained.

  The similarity calculation unit 31 obtains the similarity between the pixel block C on the screen 182 and the pixel block D on the processing target screen 183 indicated by the extrapolated motion vector. Note that the processing after obtaining the similarity is the same as the processing when the processing target screen is a P picture, and thus description thereof is omitted.

  According to the second embodiment, for a P picture, a B picture, and an I picture in the case of M = 3, it is possible to reduce coding distortion while maintaining high definition and obtain an improved moving image signal with improved image quality. it can.

  FIG. 13 is a block diagram of a third embodiment of the video decoding apparatus according to the present invention. The video decoding apparatus of FIG. 13 is different from the encoding distortion reduction apparatus of FIG. 8 in that an average luminance calculation unit 15 is added and the processing of the weighting control unit 7 and the similarity calculation unit 14.

  The similarity calculation unit 14 outputs the extracted pixel block to the average luminance calculation unit 15 in addition to the processing described above. The average luminance calculation unit 15 calculates the average luminance for each pixel block of the processing target screen input from the similarity calculation unit 14, and outputs the average luminance calculated for each pixel block to the weighting control unit 7 as luminance information.

  In the video decoding apparatus of FIG. 8, the weighting control unit 7 determines the weighting coefficient based on the block positions of the pixel blocks on the processing target screen and the reference screen and the similarity value. In the video decoding apparatus of FIG. 13, in addition to the block position of the pixel block on the processing target screen and the reference screen and the similarity value, the average luminance in the vicinity of the pixel block on the processing target screen is also taken into consideration. Effective coding distortion removal according to the characteristics can be performed.

  Weber's law is a characteristic related to the discrimination threshold of human brightness. This is a ratio ΔY / Y that is constant over a wide range, where ΔY is the minimum discriminable luminance difference with respect to a certain luminance Y. For example, literature includes “2 Video Media Equipment Standards and Issues 2-1 Broadcast Standards and Senses 2-1-1 Broadcast Standards and Vision”, Masaru Kanazawa, Yoshimichi Otsuka, Journal of the Video Information Media Society, Vol. 57, no. There are 11, 2003 years.

  That is, for example, at the boundary of block distortion having the same level difference in terms of electrical signals, block distortion appearing in an image with low luminance is more visually noticeable than block distortion appearing in an image with high luminance.

  Therefore, the average luminance in the vicinity of the pixel block on the processing target screen is obtained, and when the average luminance is high, even if coding distortion has occurred, it is not visually noticeable. Do. By performing the processing in this way, the video decoding apparatus in FIG. 13 can reduce unnecessary blurring of the processed image and performs encoding only when encoding distortion is conspicuous in human visual characteristics. Distortion can be reduced.

  Note that the range in the vicinity of the pixel block for which the average luminance is obtained is the same range as the pixel block of the processing target screen, for example. The weighting coefficient wref ′ of the reference screen at that time is calculated using the following equations (9) and (10). C is a constant.

式（９）は処理対象画面の画素ブロックの画素値の平均輝度ＡＶＥを算出している。式（１０）は平均輝度ＡＶＥに基づき、参照画面の重み付け係数ｗref′を算出している。参照画面の重み付け係数ｗref′は、処理対象画面の画素ブロックの画素値の平均輝度ＡＶＥが大きいほど、小さな値となる。

Equation (9) calculates the average luminance AVE of the pixel values of the pixel block of the processing target screen. Equation (10) calculates the weighting coefficient wref ′ of the reference screen based on the average luminance AVE. The weighting coefficient wref ′ of the reference screen becomes smaller as the average luminance AVE of the pixel values of the pixel block of the processing target screen is larger.

  That is, when the average luminance AVE of the pixel value of the pixel block of the processing target screen is large, it is not visually noticeable even if the encoding distortion occurs. Therefore, the weighting coefficient wref ′ of the reference screen is reduced to reduce the reference screen. The weighting for the pixel block is reduced.

  FIG. 14 is a flowchart of another example showing processing of the weighting control unit. The processes in steps S11 to S13 and S17 in FIG. 14 are the same as the processes in steps S1 to S3 and S5 in FIG.

  In step S14, the weighting control unit 7 calculates the weighting coefficient wref of the reference screen based on the similarity value using, for example, the equation (4). Next, proceeding to step S15, the weighting control unit 4 calculates the average luminance AVE of the pixel values of the pixel block of the processing target screen using the equation (10).

  In step S16, the weighting control unit 4 modifies the weighting coefficient wref of the reference screen to the coefficient wref ′ based on the average luminance AVE using Expression (9). The weighting control unit 7 calculates the weighting coefficient wcrt of the processing target screen based on the weighting coefficient wref ′ of the reference screen using, for example, Expression (3). In the third embodiment, the description of the same parts as those of the video decoding device in FIG. 8 is omitted.

  According to the third embodiment, with respect to the P picture and I picture when M = 1, it is possible to reduce the coding distortion while maintaining high definition and obtain an improved moving image signal with improved image quality.

  FIG. 15 is a block diagram of a fourth embodiment of the video decoding apparatus according to the present invention. The video decoding device in FIG. 15 is similar to the video decoding device in FIG. 13 in that an average luminance calculation unit 36 is added and the processing of the weighting control unit 32 and the similarity calculation unit 35 is similar to the video decoding device in FIG. Is different.

  In addition to the above processing, the similarity calculation unit 35 outputs the extracted pixel block to the average luminance calculation unit 36. The average luminance calculation unit 36 calculates the average luminance for each pixel block of the processing target screen input from the similarity calculation unit 35, and outputs the average luminance calculated for each pixel block to the weighting control unit 32 as luminance information.

  In the video decoding device of FIG. 15, in addition to the block position of the pixel block on the processing target screen and the reference screen and the similarity value thereof, the average luminance in the vicinity of the pixel block on the processing target screen is also taken into consideration. Effective coding distortion removal according to the characteristics can be performed. In the fourth embodiment, the description of the same parts as those of the video decoding device in FIGS. 12 and 13 is omitted.

  According to the fourth embodiment, for a P picture, a B picture, and an I picture in the case of M = 3, it is possible to reduce coding distortion while maintaining high definition and obtain an improved moving image signal with improved image quality. it can.

  FIG. 16 is a block diagram of a fifth embodiment of the video decoding apparatus according to the present invention. The video decoding device includes an input device 51, an output device 52, a drive device 53, an auxiliary storage device 54, a memory device 55, an arithmetic processing device 56, and an interface device 57 that are mutually connected by a bus B.

  The input device 51 includes a keyboard and a mouse, and is used for inputting various signals. The output device 52 includes a display device and is used to display various windows, data, and the like. The interface device 57 includes a modem, a LAN card, and the like, and is used for connecting to a predetermined network.

  The video decoding program of the present invention is provided by distributing the recording medium 58, downloading from a network, or the like. The recording medium 58 on which the video decoding program is recorded is information such as a recording medium such as a CD-ROM, a flexible disk, a magneto-optical disk, etc., an optical, electrical, or magnetic recording medium, a ROM, a flash memory, etc. Various types of recording media, such as a semiconductor memory that electrically records data, can be used.

  When the recording medium 58 on which the video decoding program is recorded is set in the drive device 53, the video decoding program is installed from the recording medium 58 to the auxiliary storage device 54 via the drive device 53. The video decoding program downloaded from the network is installed in the auxiliary storage device 54 via the interface device 57.

The video decoding device stores the installed video decoding program and also stores necessary files, data, and the like. The memory device 55 reads and stores the video decoding program from the auxiliary storage device 54 when the computer is activated. The arithmetic processing unit 56 can realize the various processes of the first to fourth embodiments described above according to the video decoding program stored in the memory device 55.
(Summary)
The video decoding apparatus according to the present invention may be built in a television receiver, a tuner, a set top box (STB), or the like, or a jig having a video decoding function, or a video. A chip having a decoding function may be used.

  As described above, the video decoding apparatus according to the present invention can reduce encoding distortion such as block distortion by performing time averaging processing of an image using a motion vector obtained by decoding an encoded stream. Furthermore, in the video decoding apparatus according to the present invention, adaptive weighting processing is performed based on the similarity between the pixel blocks and the position information of the matching block, thereby preventing unnecessary blurring of the video and effectively reducing the coding distortion.

  In the video decoding apparatus according to the present invention, since motion vectors included in the encoded stream are used, processing redundancy can be omitted and the processing load can be greatly reduced.

  In the above-described embodiment, the case where there is one reference image has been described, but the same processing can be performed even when there are a plurality of reference screens. In the above-described embodiment, the sequential scanning image and the interlaced scanning image are not particularly distinguished. Of course, the only difference is whether the pixel block is obtained from the frame image or the pixel block is obtained from the field image. A scanning method can also be supported.

It is an image figure of an example which shows the outline | summary of a process of P picture in case of M = 1. It is an image figure of an example which shows the outline of processing of I picture in case of M = 1. It is an image figure of an example which shows the outline of processing of P picture in the case of M = 3. It is an example image figure which shows the outline | summary of a process of the B picture in case M = 3. It is an image figure of an example which shows the outline | summary of a process of I picture in case M = 3. It is an image figure of an example which shows the GOP (Group Of Pictures) structure of M = 1. It is an image figure of an example which shows the GOP structure of M = 3. It is a block diagram of 1st Example of the video decoding apparatus by this invention. It is an image figure showing the process of the weighting control part. It is a flowchart of an example showing the process of the weight control part. It is an image figure which shows an example of pixel block cutout. It is a block diagram of 2nd Example of the video decoding apparatus by this invention. It is a block diagram of 3rd Example of the video decoding apparatus by this invention. It is a flowchart of the other example showing the process of the weight control part. It is a block diagram of 4th Example of the video decoding apparatus by this invention. It is a block diagram of 5th Example of the video decoding apparatus by this invention.

Explanation of symbols

1,21 Decoder 2,3,12,22,24,26 1 frame delay unit 4 memory 5,30 motion vector extrapolation unit 6,14,31,35 similarity calculation unit 7,32 weighting control unit 8,33 Weighted average unit 9, 13, 27, 28 Switch 10, 11, 34 Block replacement unit 15, 36 Average luminance calculation unit 23 2 frame delay unit 25 3 frame delay unit 29 Picture discrimination unit 51 Input device 52 Output device 53 Drive device 54 Auxiliary storage device 55 Memory device 56 Arithmetic processing device 57 Interface device 58 Storage medium

Claims (6)

A video decoding device that reduces coding distortion from a decoded video signal,
A decoder that decodes the encoded video signal and outputs the decoded video signal and motion vector information;
A processing target screen output from the decoded video signal and one or more reference screens temporally adjacent to the processing target screen are input, and pixels are respectively input from the processing target screen and the reference screen using the motion vector information. A similarity calculator that cuts out and outputs a block;
A time averaging process using the pixel block of the processing target screen output from the similarity calculation unit and the pixel block of the reference screen is performed to create an average pixel block, and the averaged pixel block is output Average part,
A video decoding apparatus comprising: a block replacement unit that replaces the averaged pixel block with a pixel block of the processing target screen. A weighting control unit that determines weighting based on the similarity between the pixel block of the processing target screen and the pixel block of the reference screen;
The similarity calculation unit calculates and outputs the similarity between the pixel block of the processing target screen and the pixel block of the reference screen,
The averaging unit weights the pixel block of the processing target screen and the pixel block of the reference screen based on the weight determined by the weighting control unit, and performs the averaging process to create the averaged pixel block The video decoding device according to claim 1. An average luminance calculation unit for calculating an average luminance in the vicinity of the pixel block for each pixel block of the processing target screen;
The weighting control unit determines weighting based on a similarity between a pixel block of the processing target screen and a pixel block of the reference screen and an average luminance near the pixel block of the processing target screen. 2. The video decoding device according to 2.   In the weighting control unit, the spatial position of the pixel block on the reference screen matches the spatial position of the pixel block on the processing target screen, or the spatial position of the pixel block on the reference screen and the block pattern space of the coding distortion When the positional relationship with the position coincides with the positional relationship between the spatial position of the pixel block of the processing target screen and the spatial position of the block pattern of the coding distortion, the averaging unit does not perform the averaging process. 3. The video decoding apparatus according to claim 2, wherein weighting is determined. When the similarity calculation unit cuts out each pixel block from the processing target screen and the reference screen using the motion vector information, it cuts out so that there is an overlap between the pixel blocks beyond the boundary of the pixel block,
The video decoding device according to claim 1, wherein the block replacement unit replaces the averaged pixel block with a pixel block of the processing target screen while maintaining the size of the pixel block cut out in duplicate. In a computer functioning as a video decoding device that reduces coding distortion from a decoded video signal,
Decoding the encoded video signal and outputting the decoded video signal and motion vector information;
A processing target screen output from the decoded video signal and one or more reference screens temporally adjacent to the processing target screen are input, and pixels are respectively input from the processing target screen and the reference screen using the motion vector information. Cutting out and outputting blocks; and
Performing a time averaging process using the output pixel block of the processing target screen and the pixel block of the reference screen to create an averaged pixel block, and outputting the averaged pixel block;
A video decoding program for executing the step of replacing the averaged pixel block with a pixel block of the processing target screen.

Images