JP5833888B2 - Image processing apparatus and program - Google Patents

Description

  The present invention relates to an image processing apparatus and program for performing cepstrum analysis on a decoded image.

  Conventionally, there has been a technique for performing cepstrum analysis on a decoded image and evaluating an image having block distortion.

  For example, there is a method capable of detecting block distortion at a high bit rate by changing the head luminance value and emphasizing the cepstrum peak (Non-Patent Document 1). As a technique using the cepstrum analysis result, there is a technique for detecting an image block boundary and using it for re-encoding (Patent Document 1).

Japanese Patent Laid-Open No. 10-32829

Shunsuke Komatsu et al., “Cepstrum Analysis of Image Signals with Block Distortion”, IEICE Technical Report, IT94, p. 21-24, 1994

  In the prior art, cepstrum analysis is performed to measure the block distortion phase. However, since the prior art does not analyze the inside of an image in detail, the intensity of block distortion cannot be measured. In addition, a separate encoder is required for picture type determination and GOP structure determination, and there is a problem that processing becomes complicated.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an image processing apparatus and a program capable of analyzing features related to image coding using only the cepstrum analysis result.

An image processing apparatus according to an aspect of the present invention includes: an analysis unit that performs cepstrum analysis for each region of a predetermined size with respect to a decoded image; and a block based on a magnitude of a peak value of an analysis result analyzed by the analysis unit A block distortion strength determination unit that determines a distortion strength; and a type determination unit that determines whether the region is an intra type or an inter type based on the frequency of the peak width of the analysis result .

  The image processing apparatus detects a first frame including a region determined to be an intra type by the type determination unit, and determines an interval with the highest frequency among the intervals of the first frame as the number of GOP frames. You may further provide a GOP structure determination part.

  The GOP structure determining unit may obtain an average value of the peak values for each frame and determine an intra frame based on a change in the time direction of the average value and the number of frames of the GOP. Good.

  Further, the image processing apparatus uses the GOP structure determined by the GOP structure determination unit and the average value or median value of the block distortion strength of each frame determined by the block distortion strength determination unit, You may further provide the block distortion strength correction part which corrects the intensity | strength of the block distortion for every area | region contained in each flame | frame.

  Further, the block distortion strength correction unit includes a first calculation unit that calculates an average value or a median value of block distortion strengths for each region included in each frame in one GOP, and the first calculation unit. A second calculation unit for calculating a difference between the calculated average value or the maximum value and the minimum value of the median value, and weighting the difference calculated by the second calculation unit according to the position of the frame in the GOP, An addition unit that adds the weighted difference to the intensity of block distortion for each region of the frame may be provided.

  The analysis unit may gradually reduce the predetermined size from the size of the decoded image until the width of the peak value of the analysis result becomes uniform.

  The image processing apparatus may further include a deblocking filter unit that performs a deblocking filter process using a filter offset value corrected according to the intensity of the block distortion.

In addition, the program according to another aspect of the present invention is based on the analysis step of performing cepstrum analysis for each region of a predetermined size for the decoded image, and the magnitude of the peak value of the analysis result analyzed in the analysis step. A computer executes a block distortion strength determination step for determining a block distortion strength, and a type determination step for determining whether the region is an intra type or an inter type based on the frequency of the peak width of the analysis result .

  According to the present invention, it is possible to analyze characteristics relating to image coding using only the cepstrum analysis result.

1 is a block diagram illustrating an example of a schematic configuration of an image encoding device according to Embodiment 1. FIG. The block diagram which shows an example of a structure of an information analysis part. The figure which shows an example of a cepstrum analysis result (the 1). The figure which shows an example of a cepstrum analysis result (the 2). The figure which shows an example of the change of a predetermined size. The block diagram which shows an example of a structure of a type determination part. The figure which shows an example of the type in an image. The block diagram which shows an example of a structure of a GOP structure determination part. The figure for demonstrating determination of a GOP structure. The block diagram which shows an example of a structure of a block distortion intensity correction part. 3 is a flowchart illustrating an example of information analysis processing according to the first embodiment. FIG. 6 is a block diagram illustrating an example of a configuration of an image encoding device according to a second embodiment.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In addition, although each information calculated | required from the cepstrum analysis result demonstrated in each Example can be used for various uses, the example used for a deblocking filter is demonstrated below.

[Example 1]
<Configuration>
FIG. 1 is a block diagram illustrating an example of a schematic configuration of an image encoding device 100 according to the first embodiment. In the example illustrated in FIG. 2, the image encoding device 100 includes a prediction error signal generation unit 101, an orthogonal transform unit 102, a quantization unit 103, an entropy encoding unit 104, an inverse quantization unit 105, an inverse orthogonal transform unit 106, and a decoding Image generation unit 107, deblocking filter unit 108, decoded image storage unit 109, intra prediction unit 110, inter prediction unit 111, motion vector calculation unit 112, encoding control and header generation unit 113, predicted image selection unit 114, and information An analysis unit 115 is included. An outline of each part will be described below.

  The prediction error signal generation unit 101 acquires block data obtained by dividing an encoding target image of input moving image data into blocks of 16 × 16 pixels, for example.

  The prediction error signal generation unit 101 generates a prediction error signal from the block data and the block data of the prediction image output from the prediction image selection unit 114. The prediction error signal generation unit 101 outputs the generated prediction error signal to the orthogonal transformation unit 102.

  The orthogonal transform unit 102 performs orthogonal transform processing on the input prediction error signal. The orthogonal transform unit 102 outputs a signal separated into horizontal and vertical frequency components by the orthogonal transform process to the quantization unit 103.

  The quantization unit 103 quantizes the output signal from the orthogonal transform unit 102. The quantization unit 103 reduces the code amount of the output signal by quantization, and outputs this output signal to the entropy encoding unit 104 and the inverse quantization unit 105.

  The entropy encoding unit 104 performs entropy encoding on the output signal from the quantization unit 103 and the motion vector information acquired from the motion vector calculation unit 112 and outputs the result. Entropy coding is a method of assigning variable-length codes according to the appearance frequency of symbols.

  The inverse quantization unit 105 dequantizes the output signal from the quantization unit 103 and then outputs the output signal to the inverse orthogonal transform unit 106. The inverse orthogonal transform unit 106 performs an inverse orthogonal transform process on the output signal from the inverse quantization unit 105 and then outputs the output signal to the decoded image generation unit 107. By performing decoding processing by the inverse quantization unit 105 and the inverse orthogonal transform unit 106, a signal having the same level as the prediction error signal before encoding is obtained.

  The decoded image generation unit 107 adds the block data of the image subjected to motion compensation by the inter prediction unit 111 and the prediction error signal decoded by the inverse quantization unit 105 and the inverse orthogonal transform unit 106. The decoded image generation unit 107 outputs the decoded image block data generated by the addition to the information analysis unit 115 and the deblocking filter unit 108.

  The information analysis unit 115 performs cepstrum analysis for each region of a predetermined size on the decoded image, and detects various types of information from the cepstrum analysis result. Various types of information include, for example, the strength of block distortion. For example, the information analysis unit 115 outputs the block distortion strength to the deblocking filter unit 108. Details of the information analysis unit 115 will be described later with reference to FIG.

  The deblocking filter unit 108 applies a filter for reducing block distortion to the decoded image output from the decoded image generation unit 107 and outputs the filtered image to the decoded image storage unit 109. At this time, the deblocking filter unit 108 changes the filter strength using the block distortion strength acquired from the information analysis unit 115.

  The decoded image storage unit 109 stores the input block data of the decoded image as new reference image data, and outputs the data to the intra prediction unit 110, the inter prediction unit 111, and the motion vector calculation unit 112.

  The intra prediction unit 110 generates a predicted image from reference pixels that have already been encoded for the processing target block of the encoding target image.

  The inter prediction unit 111 performs motion compensation on the reference image data acquired from the decoded image storage unit 109 with the motion vector provided from the motion vector calculation unit 112. Thereby, block data as a motion-compensated reference image is generated.

  The motion vector calculation unit 112 obtains a motion vector using the block data in the encoding target image and the reference image acquired from the decoded image storage unit 109. The motion vector is a value indicating a spatial deviation in units of blocks obtained using a block matching technique for searching for a position most similar to the processing target block from the reference image in units of blocks. The motion vector calculation unit 112 outputs the obtained motion vector to the inter prediction unit 111, and outputs motion vector information including information on the motion vector and the position of the reference image to the entropy encoding unit 104.

  The block data output from the intra prediction unit 110 and the inter prediction unit 111 are input to the predicted image selection unit 114.

  The predicted image selection unit 114 selects one of the block data acquired from the intra prediction unit 110 and the inter prediction unit 111 as a predicted image. The selected prediction image is output to the prediction error signal generation unit 101.

  The encoding control and header generation unit 113 performs overall encoding control and header generation. The encoding control and header generation unit 113 notifies the intra prediction unit 110 of presence / absence of slice division, notifies the deblocking filter unit 108 of presence / absence of deblocking filter, and provides a reference image to the motion vector calculation unit 112. Notification of restrictions, etc.

  The encoding control and header generation unit 113 uses the control result, for example, H.264. H.264 / AVC header information is generated. The generated header information is output to the entropy encoding unit 104, and is output as a stream together with image data and motion vector data.

<Configuration of information analysis unit>
Next, the configuration of the information analysis unit 115 will be described. FIG. 2 is a block diagram illustrating an example of the configuration of the information analysis unit 115. The information analysis unit 115 illustrated in FIG. 2 includes an analysis unit 201, a block strain strength determination unit 202, a type determination unit 203, a GOP structure determination unit 204, and a block strain strength correction unit 205.

  The analysis unit 201 sequentially obtains the decoded images from the decoded image generation unit 107, and performs cepstrum analysis for each area of a predetermined size of the decoded image. The predetermined size is, for example, 64 × 64 of a size including a macro block. The analysis unit 201 may reduce the predetermined size in order from the image size until a predetermined condition is satisfied. This will be described later with reference to FIG.

  The analysis unit 201 performs one-dimensional cepstrum analysis for each region in each horizontal and vertical direction. For example, when performing the horizontal cepstrum analysis, the analysis unit 201 performs cepstrum analysis for each row in the region, and calculates the average of the analysis results of each row. Thereby, the analysis unit 201 obtains a horizontal cepstrum analysis result of this region. The vertical direction is similarly performed.

  The cepstrum analysis in the horizontal and vertical directions may use a known technique, for example, a technique described in Non-Patent Document 1. The analysis unit 201 may calculate the total cepstrum by taking the square root of the sum from the mean square of the analysis results for each horizontal and vertical direction.

  FIG. 3 is a diagram illustrating an example of a cepstrum analysis result (part 1). FIG. 3 shows the result of cepstrum analysis performed in a horizontal direction on a region including an intra block, for example. An intra block refers to, for example, a macro block on which intra prediction is performed.

  As shown in FIG. 3, in the region including the intra block, the peak width of the analysis result is substantially uniform. This is because the intra-block has no motion compensation, so that the regularity of the block boundary is maintained.

  FIG. 4 is a diagram illustrating an example of a cepstrum analysis result (part 2). FIG. 4 shows the result of cepstrum analysis in the horizontal direction for an area including an intra block and an inter block, for example. An inter block refers to a macro block in which inter-screen prediction is performed, for example.

  As shown in FIG. 4, in the region including the intra block and the inter block, many small peaks appear with respect to the maximum peak. This is because there is motion compensation in the inter block, so that the block boundary moves by the motion vector.

  Therefore, in the analysis result of the region including the intra block and the inter block, many peaks are generated other than the maximum peak as compared with the analysis result of the region including the intra block.

  Next, the analysis unit 201 may perform the cepstrum analysis while reducing the predetermined size of the region until a predetermined condition is satisfied. For example, the predetermined size is successively reduced to a half size from the size of the decoded image.

  FIG. 5 is a diagram illustrating an example of a change in the predetermined size. The analysis unit 201 performs analysis using the predetermined size 20 including the decoded image 11 illustrated in FIG. The predetermined size 20 may be a little larger than the decoded image 11.

  Next, if the analysis result in the horizontal / vertical direction in the region of the predetermined size 20 is not the analysis result as shown in FIG. 3, the analysis unit 201 divides the vertical / horizontal direction of the predetermined size 20 by 2 to obtain the predetermined size 21. The analysis result as shown in FIG. 3 indicates that the peak width is uniform. In FIG. 4, the peak width is non-uniform when small peaks are included. Here, the predetermined condition is, for example, that the peak width is uniform.

  Next, if the analysis result in the horizontal / vertical direction in the region of the predetermined size 21 is not the analysis result as shown in FIG. 3, the analysis unit 201 divides the vertical / horizontal direction of the predetermined size 21 by 2 to obtain the predetermined size 22 Hereinafter, the analysis unit 201 reduces the predetermined size until the peak width of the analysis result of the region of the predetermined size is uniform in any region. The lower limit of the predetermined size is, for example, the macro block size.

  That is, the analysis unit 201 decreases the predetermined size until both horizontal and vertical analysis results satisfy a predetermined condition in one region among the plurality of divided regions. The analysis unit 201 outputs the analysis result finally analyzed to the block strain strength determination unit 202 and the type determination unit 203.

  The analysis unit 201 uses an image encoding technique such as H.264. When slices can be divided within one frame as in H.264 / AVC, a method of changing the predetermined size may be used. This is because when an intra slice and an inter slice are included in one frame, the peak widths of the analysis results are not always uniform in a region having a preset size. The analysis unit 201 gradually decreases the predetermined size, thereby specifying the region including the intra block and making it easier to specify the position of the intra slice.

  In addition, when the image encoding technique is such that the intra and inter types are determined in one frame, such as MPEG2, for example, the predetermined size of the area may be set in advance.

  Returning to FIG. 2, the block distortion strength determination unit 202 will be described. The block distortion strength determination unit 202 determines the block distortion strength based on the magnitude of the peak value of the analysis result acquired from the analysis unit 201.

  For example, the block distortion strength determination unit 202 performs clustering on all element values of the horizontal cepstrum with k = 2 in the k-means method, and calculates the average value or median value of the cluster having the larger cluster median value in the horizontal direction. The peak value. The block distortion strength determination unit 202 performs the same for the vertical direction.

  For example, the block distortion strength determination unit 202 determines the magnitude of the peak value at each block boundary as the block distortion strength. The block distortion determination unit 202 outputs the determined horizontal and vertical block distortion strengths to the GOP structure determination unit 204 and the block distortion strength correction unit 205.

  The type determination unit 203 acquires a cepstrum analysis result for each region from the analysis unit 201, and determines whether the type of each region is inter or intra. Here, as described above, in the case of an intra slice, block distortions are arranged uniformly, so that the peak width of the cepstrum is uniform. On the other hand, in the case of the inter slice, the block distortions are arranged non-uniformly due to motion compensation, and therefore the cepstrum peak width is non-uniform.

  FIG. 6 is a block diagram illustrating an example of the configuration of the type determination unit 203. The type determination unit 203 illustrated in FIG. 6 includes a frequency calculation unit 301 and an intra / inter determination unit 302.

  The frequency calculation unit 301 calculates the peak width frequency of the horizontal and vertical cepstrum analysis results for each region, and generates a peak width histogram. The frequency calculation unit 301 outputs the generated histogram to the intra / inter determination unit 302.

  The intra / inter determination unit 302 determines that this area is intra if the frequency of 16 (macro) block size often used in encoding is equal to or greater than a predetermined ratio in the horizontal / vertical histogram. The predetermined ratio is, for example, 85%.

  In addition, if the frequency of the block size of 16 is less than a predetermined ratio, the intra / inter determination unit 302 sets this area as inter. The intra / inter determination unit 302 outputs the determined type to the GOP structure determination unit 204 in association with the region. The type determination unit 203 performs histogram generation and type determination for all regions.

  FIG. 7 is a diagram illustrating an example of types in an image. A region 30 in one image 11 illustrated in FIG. 7 includes each region determined to be intra, and a region 31 includes each region determined to be inter. The region 30 corresponds to, for example, an intra slice, and the region 31 corresponds to an inter slice. As described above, the intra / inter determination unit 302 can determine the slice position and the type of the slice.

  Returning to FIG. 2, the GOP structure determination unit 204 will be described. First, as foresight knowledge, in general coding, intra slices exist at regular intervals. Further, with respect to the intra slice, the later inter slice has a high possibility that the image quality deteriorates and the block distortion increases as the distance increases. In addition, although related to the coding setting, the image quality of the B slice is worse than that of the P slice, and the block distortion is likely to increase.

  The GOP structure determination unit 204 determines the GOP structure based on the block distortion strength acquired from the block distortion strength determination unit 202 and the type of each region acquired from the type determination unit 203 using this foresight knowledge.

  FIG. 8 is a block diagram illustrating an exemplary configuration of the GOP structure determination unit 204. The GOP structure determination unit 204 illustrated in FIG. 8 includes a frame detection unit 401, a frequency calculation unit 402, and an intra / inter determination unit 403.

  The frame detection unit 401 detects a first frame including a region or an intra slice associated with an intra. The frame detection unit 401 notifies the frequency calculation unit 402 of the detected first frame.

  The frequency calculation unit 402 calculates the interval between the first frames notified from the frame detection unit 401 and generates a histogram of the intervals between the first frames. The frequency calculation unit 402 outputs the calculated histogram to the intra / inter determination unit 403.

  The intra / inter determining unit 403 determines the interval value having the highest frequency in the histogram acquired from the frequency calculating unit 402 as the number of GOP frames (referred to as GOP value). Also, the intra / inter determining unit 403 examines the interval between the first frames, and determines a frame having an interval that matches the determined GOP value as an intra frame. Also, the intra / inter determining unit 403 determines a frame other than the frame determined to be an intra frame as an inter frame.

  Note that the intra / inter determining unit 403 may determine an intra frame based on, for example, a change in the time direction with respect to an average value of peak values in the horizontal and vertical directions for each frame. Even if the first frame and the frame that should be detected are not detected, an intra frame can be detected in consideration of the average of the GOP value and the peak value of the frame.

  Here, when the first frame is not detected at a position where an intra frame exists, the frame at that position is referred to as a second frame. The average value of the peak values and the GOP value are used for determining whether or not the second frame is an intra frame.

  The intra / inter determination unit 403 first detects the second frame based on the GOP value. The intra / inter determination unit 403 determines that the second frame is an intra frame if the average value of the peak values of the analysis results of the frame immediately before the second frame and the second frame changes from large to small. And decide.

  This is based on the idea that the intra-frame has little block distortion and the inter-frame that is temporally separated from the intra frame has much block distortion. The intra / inter determining unit 403 outputs the determined information to the block distortion strength correcting unit 205.

  FIG. 9 is a diagram for explaining determination of the GOP structure. Reference numerals 50 to 64 shown in FIG. 9 indicate one image (frame). For example, it is assumed that the frames 50, 57, and 64 are determined as intra frames by the intra / inter determination unit 403.

  At this time, the intra / inter determining unit 403 determines the GOP value as “7” in the frames 50 to 56.

  It is assumed that the intra frame 57 is not detected by the frame detection unit 401 as the first frame. Further, it is assumed that the highest frequency of the histogram calculated by the frequency calculation unit 402 is “7”.

  At this time, the intra / inter determination unit 403 determines an intra frame using the average value of the block distortion strength for each frame acquired from the block distortion strength determination unit 202. Note that the intra / inter determining unit 403 may use the block distortion strength in one or both of the horizontal direction and the vertical direction in the frame when calculating the average value of the block distortion strength. The intra / inter determining unit 403 can estimate that the frame 57 from the intra frame 50 and the intra frame 64 is an intra frame in consideration of the GOP value.

  If the average value of the block distortion strength between the frame 56 immediately before the estimated frame 57 and the frame 57 is changed from “large” to “small”, the intra / inter determination unit 403 It is determined that For example, the average value can be determined to be “large” if it is larger than the threshold, and “small” if it is smaller than the threshold.

  Returning to FIG. 2, the block distortion strength correcting unit 205 will be described. The block distortion strength correcting unit 205 corrects the acquired block distortion strength in each horizontal and vertical direction so that a stronger deblocking filter is applied to an inter frame that is farther from an intra frame.

  FIG. 10 is a block diagram illustrating an example of the configuration of the block distortion strength correction unit 205. The block distortion strength correction unit 205 illustrated in FIG. 10 includes an average value / median value calculation unit 501, a difference calculation unit 502, and an addition unit 503.

  The average value / median value calculation unit 501 calculates the average value or the median value of the block distortion intensities for each region included in each frame. The average value / median value calculation unit 501 outputs the calculated average value or median value of each frame to the difference calculation unit 502.

  The difference calculation unit 502 calculates a difference between the maximum value and the minimum value among the acquired average value or median value of each frame. The difference calculation unit 502 outputs the calculated difference value to the addition unit 503.

The adding unit 503 corrects the strength of the block distortion based on the difference value acquired from the difference calculating unit 502 and the GOP structure acquired from the GOP structure determining unit 204. For example, the adding unit 503 corrects the strength of block distortion using the following equation (1).
Correction value = (n × Diff) / G (1)
n (= 0, 1, 2,...): Frame number Diff: difference value G: GOP value when the first frame 0 of the GOP structure is set. The addition unit 503 sets this correction value for each frame n. The block distortion strength is corrected by adding to the block distortion strength of the region. The adding unit 503 outputs the corrected block distortion strength to the deblocking filter unit 108.

  The deblocking filter unit 108 corrects the filter offset value α, for example, using the horizontal or vertical block distortion strength. The deblocking filter unit 108 increases the offset value α so as to apply a strong deblocking filter if the strength of the block distortion is large.

  The correction of the block distortion strength is not necessarily a necessary process, and the deblocking filter unit 108 may perform the filtering process using the block distortion strength determined by the block distortion strength determination unit 202.

<Operation>
Next, the operation of the image encoding device 100 according to the first embodiment will be described. FIG. 11 is a flowchart illustrating an example of information analysis processing according to the first embodiment.

  In step S101 illustrated in FIG. 11, the analysis unit 201 acquires a decoded image, and performs cepstrum analysis on the decoded image in the horizontal and vertical directions for each region of a predetermined size.

  In step S102, the block distortion strength determination unit 202 acquires horizontal and vertical cepstrum analysis results, and determines the block distortion strength based on the peak value of the cepstrum analysis results. For example, the block distortion strength determination unit 202 sets the magnitude of the peak value as the block distortion strength.

  In step S103, the type determination unit 203 forms a histogram of the peak width of the cepstrum analysis result for each region, and determines whether 16 widths in the horizontal and / or vertical direction are equal to or greater than a predetermined ratio. The type determination unit 203 determines that the area is intra if the width of 16 is equal to or greater than a predetermined ratio, and determines that the area is inter if the width of 16 is less than the predetermined ratio. Note that the processes in steps S102 and S103 are in no particular order.

  In step S104, the GOP structure determination unit 204 determines the frame GOP structure based on the region type and the peak value of the region. The GOP structure includes the number of frames in one GOP (GOP value) and the intra / inter type of the frame in the GOP.

  The GOP structure determination unit 204 detects the first frame including the intra-type region, forms a histogram of the intervals between the first frames, and sets the interval with the highest frequency as the GOP value. The GOP structure determination unit 204 determines the first frame corresponding to the GOP value interval as an intra frame.

  The GOP structure determination unit 204 can also determine a frame that is not the first frame as an intra frame by using the GOP value and the average value of the peak values in the frame. As described above, this is performed using the idea that the block distortion increases as the distance from the intra frame increases.

  In step S <b> 105, the block distortion strength correction unit 205 corrects the block distortion strength acquired from the block strain strength determination unit 202 using the GOP structure acquired from the GOP structure determination unit 204.

  The block distortion strength correction unit 205 calculates a correction value for each frame using, for example, Equation (1), and adds the correction value to the block distortion strength for each region in the frame, thereby obtaining Correct the strength of the.

  The corrected block distortion strength is used by the deblocking filter unit 108 to correct the filter offset value. For example, by increasing the value of the filter offset value α as the block distortion intensity increases, the block is subjected to stronger deblocking filter processing.

  As described above, according to the first embodiment, it is possible to analyze the characteristics related to image coding using only the cepstrum analysis result. In the first embodiment, the example in which the block distortion strength is used for the deblocking filter has been described. However, the block distortion strength detected by the information analysis unit 115, the slice type information, the GOP structure, and the like are processed in a later stage. It may be used.

  For example, the slice type information and the GOP structure may be used for re-encoding, and the block distortion strength may be used for subjective image quality evaluation of an image. Therefore, information determined or determined only from the cepstrum analysis result may be used in any subsequent processing.

[Example 2]
FIG. 12 is a block diagram illustrating an example of the configuration of the image encoding device 600 according to the second embodiment. The image encoding device 600 is an example of a device in which the image encoding processing described in the first embodiment is implemented by software.

  As illustrated in FIG. 12, the image encoding apparatus 600 includes a control unit 601, a main storage unit 602, an auxiliary storage unit 603, a drive device 604, a network I / F unit 606, an input unit 607, and a display unit 608. These components are connected to each other via a bus so as to be able to transmit and receive data.

  The control unit 601 is a CPU that controls each device, calculates data, and processes in a computer. The control unit 601 is an arithmetic device that executes a program of image encoding processing including filter processing stored in the main storage unit 602 or the auxiliary storage unit 603. The control unit 601 receives data from the input unit 607 and the storage device, calculates and processes the data, and then outputs the data to the display unit 608 and the storage device.

  The control unit 601 can realize the information analysis processing described in each embodiment by executing a program for image encoding processing including information analysis processing.

  The main storage unit 602 is a ROM (Read Only Memory), a RAM (Random Access Memory), or the like. The main storage unit 602 is a storage device that stores or temporarily stores programs and data such as OS (Operating System) and application software that are basic software executed by the control unit 601.

  The auxiliary storage unit 603 is an HDD (Hard Disk Drive) or the like, and is a storage device that stores data related to application software or the like.

  The drive device 604 reads the program from the recording medium 605, for example, a flexible disk, and installs it in the storage device.

  A predetermined program is stored in the recording medium 605, and the program stored in the recording medium 605 is installed in the image encoding apparatus 600 via the drive device 604. The installed predetermined program can be executed by the image encoding apparatus 600.

  The network I / F unit 606 is a peripheral having a communication function connected via a network such as a LAN (Local Area Network) or a WAN (Wide Area Network) constructed by a data transmission path such as a wired and / or wireless line. This is an interface between the device and the image encoding device 600.

  The input unit 607 includes a keyboard having cursor keys, numeric input, various function keys, and the like, a mouse and a slice pad for performing key selection on the display screen of the display unit 608, and the like. The input unit 607 is a user interface for a user to give an operation instruction to the control unit 601 and input data.

  The display unit 608 is configured by a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), or the like, and performs display according to display data input from the control unit 601.

  The decoded image storage unit 109 illustrated in FIG. 1 is realized by, for example, the main storage unit 602 or the auxiliary storage unit 603, and the configuration other than the decoded image storage unit 109 illustrated in FIG. 1 includes, for example, a control unit 601 and a work memory. This can be realized by the main storage unit 602.

  The program executed by the image encoding device 600 has a module configuration including each unit described in the first embodiment. As actual hardware, when the control unit 601 reads a program from the auxiliary storage unit 603 and executes it, one or more of the above-described units are loaded onto the main storage unit 602, and one or more of the units are main. It is generated on the storage unit 602.

  As described above, the information analysis processing described in the first embodiment may be realized as a program for causing a computer to execute. The information analysis process described above can be realized by installing this program from a server or the like and causing the computer to execute it.

  It is also possible to record the program in the recording medium 605 and cause the computer or portable terminal to read the recording medium 605 on which the program is recorded, thereby realizing the information analysis process described above. The recording medium 605 is a recording medium that records information optically, electrically, or magnetically, such as a CD-ROM, flexible disk, magneto-optical disk, etc., and information is electrically stored, such as a ROM or flash memory. Various types of recording media such as a semiconductor memory for recording can be used.

  In the embodiment, the image encoding apparatus has been described as an example, but the information analysis process can be similarly applied to the image decoding apparatus. The image encoding device and the image decoding device are collectively referred to as an image processing device.

  The program executed by the image processing apparatus has a module configuration including the above-described units. As actual hardware, the control unit 601 reads out the program from the auxiliary storage unit 604 and executes the program, so that one of the above units is included. Alternatively, a plurality of units are loaded on the main storage unit 602, and one or a plurality of units are generated on the main storage unit 602.

  Each embodiment has been described in detail above. However, the present invention is not limited to the specific embodiment, and various modifications and changes other than the above-described modification are possible within the scope described in the claims. .

100, 600 Image coding apparatus 101 Predicted image generation unit 102 Orthogonal transformation unit 103 Quantization unit 104 Entropy coding unit 105 Inverse quantization unit 106 Inverse orthogonal transformation unit 107 Decoded image generation unit 108 Deblocking filter unit 109 Decoded image storage unit 110 Intra Prediction Unit 111 Inter Prediction Unit 112 Motion Vector Calculation Unit 113 Coding Control and Header Generation Unit 114 Predictive Image Selection Unit 201 Analysis Unit 202 Block Distortion Strength Determination Unit 203 Type Determination Unit 204 GOP Structure Determination Unit 205 Block Distortion Strength Correction Unit 301 Frequency calculation unit 302 Intra / inter determination unit 401 Frame detection unit 402 Frequency calculation unit 403 Intra / inter determination unit 501 Average value / median value calculation unit 502 Difference calculation unit 503 Addition unit 601 Control unit 602 Main storage unit 603 Auxiliary storage unit 604 Eve 606 network I / F unit 607 input unit 608 display unit

Claims (8)

An analysis unit that performs cepstrum analysis for each region of a predetermined size for the decoded image;
A block distortion strength determination unit that determines the strength of block distortion based on the magnitude of the peak value of the analysis result analyzed by the analysis unit;
A type determination unit that determines whether the region is an intra type or an inter type based on the frequency of the peak width of the analysis result;
An image processing apparatus comprising: A GOP structure determining unit that detects a first frame including an area determined to be an intra type by the type determining unit, and determines the most frequent interval as the number of GOP frames among the intervals of the first frame; The image processing apparatus according to claim 1 . The GOP structure determination unit
The image processing apparatus according to claim 2 , wherein an average value of the magnitudes of the peak values is obtained for each frame, and an intra frame is determined based on a change in the time direction of the average value and the number of frames of the GOP. For each region included in each frame, using the GOP structure determined by the GOP structure determination unit and the average or median value of the block distortion strength of each frame determined by the block distortion strength determination unit the image processing apparatus according to claim 2 or 3, wherein further comprising a block distortion intensity correcting section for correcting the intensity of the block distortion. The block distortion strength correcting unit is
In one GOP, a first calculation unit that calculates an average value or median value of block distortion strength for each region included in each frame;
A second calculation unit for calculating a difference between a maximum value and a minimum value of the average value or the median value calculated by the first calculation unit;
The difference calculated by the said 2nd calculation part is weighted according to the position of the frame in GOP, and the addition part which adds the weighted difference to the intensity | strength of the block distortion for every area | region of this frame is provided. 4. The image processing apparatus according to 4 . The analysis unit
Said predetermined size, the image processing apparatus according to claim 1 to 5 any one width of the peak value of the analysis result is gradually reduced from the size of the decoded image until uniform. The image processing apparatus according to claim 1 to 6 any one, further comprising a deblocking filter unit which performs deblocking filtering with the modified filter offset value according to the intensity of the block distortion. An analysis step for performing cepstrum analysis for each region of a predetermined size for the decoded image;
A block distortion strength determination step for determining a block distortion strength based on the magnitude of the peak value of the analysis result analyzed in the analysis step ;
A type determination step for determining whether the region is an intra type or an inter type based on the frequency of the peak width of the analysis result;
A program that causes a computer to execute.

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