CN112750077B - Parallelized synthetic aperture radar image sub-band splicing effect processing method - Google Patents
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Abstract
The invention discloses a parallelization processing method for sub-band splicing effect of synthetic aperture radar images, which comprises the following steps: s1, reading in an image, and preprocessing the image to obtain an image to be processed; s2, blocking processing is conducted on the large-size image; s3, parallelly processing the sub-image blocks subjected to the blocking step; and S4, calculating and estimating sub-band splicing errors in a parallelization manner. The method can improve the processing effect of the algorithm when processing the sub-band splicing effect, reduce the error of image processing, and meanwhile, the parallelization calculation method can effectively improve the processing efficiency of the sub-band splicing effect and can be widely applied to the field of SAR image processing.
Description
Technical Field
The invention relates to the field of signal processing, in particular to a parallelized synthetic aperture radar image sub-band splicing effect processing method.
Background
The synthetic aperture radar is used as an active microwave sensor, has the characteristic of realizing all-weather earth observation all day long without limitation of illumination, weather conditions and the like, has wide application prospect in civil fields such as agriculture, forestry, oceans or geological and natural disasters, and has unique advantages in the military field.
Nowadays, the requirement of space-to-ground observation is continuously increasing, and in order to realize wide-area large-area observation, a ScanSAR (scanning synthetic aperture radar) and TOPS (top surface) working modes are developed by a satellite-borne SAR system. The working mode obtains larger imaging bandwidth by periodically adjusting the attitude of the antenna. However, such an operation mode brings about the problems of non-uniform system gain and sub-band splicing errors, i.e., scallop effect and sub-band splicing effect. Although the TOPS mode has been effective in solving the scallop effect problem, transitions between sub-bands still exist. At present, a Kalman filtering-based method achieves a satisfactory effect in the aspect of correcting the sub-band splicing effect, but the method still has some problems. Firstly, if the azimuth of the SAR image corresponds to the column of the image, the method regards the sub-band splicing error on each column of the image as a constant, and then uses a Kalman filter to estimate the constant error. On the other hand, the algorithm needs to estimate the subband error of each column of the image, the calculation amount is large, and the timeliness requirement is difficult to meet in practical application.
Disclosure of Invention
The invention aims to overcome the defects of the background technology, and provides a parallelized processing method for the sub-band splicing effect of a synthetic aperture radar image, so that the block processing idea is provided for solving the problem that the existing mathematical model is poor in fitting on a large image; aiming at the problem of computing timeliness, an idea of parallelizing the algorithm is provided; the invention can improve the processing effect of the algorithm when processing the sub-band splicing effect, reduce the error when processing the image, and simultaneously, the parallelization calculation method can effectively improve the processing efficiency of the sub-band splicing effect.
The invention provides a parallelization processing method for sub-band splicing effect of synthetic aperture radar images, which comprises the following steps: s1, reading in an image, and preprocessing the image to obtain an image to be processed; s2, blocking processing is conducted on the large-size image; s3, parallelly processing the sub-image blocks subjected to the blocking step; and S4, calculating and estimating the sub-band splicing error in a parallelization mode.
In the above technical solution, the specific steps of step S1 are as follows: s11, judging the stripe direction in the image, specifically judging whether sub-band splicing error stripes, namely the azimuth direction of the SAR image, are parallel to the longitudinally arranged column distribution of the image, and if not, transposing the image; and S12, determining a sub-band interval D.
In the above technical solution, the specific steps of step S2 are as follows: s21, calculating the image size: length + width = M + N, i.e. the image has M rows and N columns; s22, judging whether the block division is needed or not, and if M is less than 2000, directly entering the step S4; if M is greater than 2000, the image needs to be subjected to blocking processing; s23, dividing the image columns, wherein the image blocking method comprises the following steps: actual number of divided blocks s: s = Floor (M/1000), where Floor () is a Floor function, and if MOD (M/1000) =0, the division result is s 1000 image blocks of 1000 × N size, and if MOD (M/1000) = x, the division result is s-1 image blocks of 1000 × N size and one image block of (1000 +x) ×.n size.
In the above technical solution, the specific steps of step S3 are as follows: s31, determining the corresponding index position of the image block in the original image, and calculating the original Mean value [ Mean _1, mean _2, \8230 ] of each image block, mean _ S]So as to facilitate image splicing after processing; s32, respectively carrying out sub-band splicing effect suppression on the image blocks by using a sub-band splicing effect processing algorithm based on Kalman filtering on the S image blocks, and equally dividing computing tasks to available computing nodes for distributed parallel computing; s33, mean value correction is carried out on the S image blocks to ensure that brightness jump does not occur at the spliced positions of the image blocks after splicing, and the mean value correction method comprises the following steps:
wherein I output_x (m, n) and I' output_x (m, n) are respectively the pixel values of the (m, n) th image block after sub-band splicing effect suppression and the pixel values of the (m, n) th image block after Mean value adjustment, mean _ x is the original Mean value of the x-th image block, and Output _ x _ Mean is the Mean value of the x-th image block after sub-band splicing effect suppression; and S34, splicing the S image blocks again according to the index positions to obtain a final processing result.
In the above technical solution, the specific steps of step S32 are as follows: s321, calculating mean and variance var of the neighborhood region of the current column, and estimating a sub-band splicing error o corresponding to each column of pixels of the image block by using a Kalman filter according to an additive model of the sub-band splicing error and taking mean and var as parameters S (ii) a S322, sub-band splicing error correction is carried out, and sub-band splicing errors corresponding to a row are directly subtracted from the row in the original image to obtain a sub-band splicing inhibition result; and S323, sequentially performing the steps S321 and S322 line by line until the whole image is processed, and obtaining a sub-band splicing inhibition result.
In the above technical solution, the specific steps of step S4 are as follows: s41, if the image does not need to be blocked, directly carrying out sub-band splicing effect processing based on a Kalman filter; s42, if the image is blocked, calculating parameters required by the Kalman filter; s43, distributing the current image matrix data calculated in the step S42 to a calculation node, and performing sub-band splicing error estimation based on a Kalman filter to obtain a sub-band splicing error estimation result obtained by each column of the image; s44, correcting the original image according to the sub-band splicing error estimation result to obtain a final processing result, namely finishing the sub-band splicing effect suppression of the image.
In the above technical solution, the specific process of step S42 is as follows: s421, when a Kalman filter is used for sub-band error estimation, the calculation of input parameters is completed before distributed parallel calculation, the input parameters of the Kalman filter comprise the mean value of the left and right neighborhoods of the current estimation column, the variance of the left and right neighborhoods of the current estimation column and the observed value of the current column, wherein the calculation method of the domain mean value and the domain variance comprises the following steps: if the current column is the ith column, calculating the image from
Is listed to
The mean and variance of the area corresponding to the column are the neighborhood mean and the neighborhood variance of the ith column; s422, storing neighborhood mean values and neighborhood variance parameters corresponding to each row of pixels into the M +1 th row and the M +2 th row of each row, wherein each row of data of the image matrix comprises original pixels of the image, the neighborhood mean values and the neighborhood variances.
In the above technical solution, in the step S12, the subband splicing error stripe direction is parallel to the column, and the subband interval D =3000; in step S2, M =18742, n =12776, and M >2000, the blocking process is required to obtain 18 sub-images.
In the above technical solution, the distributed computation of step S3 adopts a computation architecture based on Hadoop, and the implementation steps are as follows: uploading data to be processed to an HDFS (Hadoop distributed File System), and then outputting data to be sub image blocks to be processed in a form of < key, value >, wherein the key is a position index corresponding to the image block, and the value corresponds to the image block to be processed; the Mapper acquires < key, value > data to be processed, performs sub-band splicing effect suppression based on Kalman filtering in step 32, outputs a processing result in the form of < key, value >, adjusts the mean value of the image in the reduce process, and performs splicing according to the index position to finally obtain the processing result of the whole image.
In the above technical solution, the step S4 is calculated based on a Hadoop architecture, and the data to be processed is output in a form of < key, value >, where key is a position index of a current column in an image, and value is a vector formed by pixel values of the current column and a neighborhood mean neighborhood variance corresponding to the current column; then, the Mapper acquires < key, value > data to be processed, a Kalman filter is used for estimating sub-band splicing errors in the pixels of the column, the obtained estimation result is transmitted in a < key, value > form, at the moment, the key is the position index of the current column in the image, and the value is the sub-band splicing errors of the current column; and then executing a Reduce process, and correcting the sub-band splicing error in the original image according to the index position so as to obtain a final processing result, namely completing the processing of the sub-band splicing effect of the image.
The parallelized processing method for the sub-band splicing effect of the synthetic aperture radar image has the following beneficial effects:
(1) The improved parallelization processing technology for the sub-band splicing effect of the synthetic aperture radar can weaken the adverse effect of the modeling defect of the sub-band splicing effect of the original algorithm on the processing result, and can effectively inhibit the sub-band splicing effect in the image.
(2) The improved parallelization calculation improvement related to the improved parallelization synthetic aperture radar sub-band splicing effect processing technology can adapt to the processing of images with various sizes, and the processing result of the original algorithm cannot be influenced.
(3) The improved parallelization processing technology for the sub-band splicing effect of the synthetic aperture radar is high in efficiency, parallelization improvement is carried out on a sub-band splicing effect processing algorithm based on Kalman filtering, and the processing efficiency of the algorithm can be effectively improved.
Drawings
FIG. 1 is a schematic overall flow chart of a parallelized SAR image sub-band stitching effect processing method according to the present invention;
FIG. 2 is a schematic diagram of image blocking and image blocking results in step two of the parallelized SAR image sub-band stitching effect processing method of the present invention;
FIG. 3 is a schematic flow chart of step three of the parallelized SAR image sub-band stitching effect processing method according to the present invention;
FIG. 4 is a schematic flow chart of step four of the parallelized SAR image sub-band stitching effect processing method of the present invention;
FIG. 5 is a prior art scanning mode synthetic aperture radar image with sub-band stitching effect in an embodiment;
FIG. 6 is the results of FIG. 5 without the chunking direct process;
FIG. 7 is the result of the chunking process of FIG. 5;
fig. 8 is a diagram showing the comparison between the result of the blocking process of fig. 5 and the original result without the blocking process.
Detailed Description
The invention is described in further detail below with reference to the following figures and examples, which should not be construed as limiting the invention.
The improved parallelization processing technology for the image sub-band splicing effect of the synthetic aperture radar is based on a sub-band splicing effect processing algorithm based on a Kalman filter, solves the problem of poor fitting performance of an additive mathematical model in an original algorithm in a large-size image by using the idea of image blocking processing, and improves the processing efficiency of the sub-band splicing effect by performing parallel processing on a plurality of image blocks; in addition, the invention carries out parallelization improvement on the step of sub-band splicing error estimation in the original algorithm, so that the processing efficiency of the image without block processing can be improved.
The invention discloses a parallelized processing method for sub-band splicing effect of synthetic aperture radar images, which has a flow chart shown in figure 1 and specifically comprises the following steps:
the method comprises the following steps: reading in an image, and preprocessing the image to obtain an image to be processed;
this step includes two parts:
(1) Judging the stripe direction in the image, specifically judging whether the sub-band splicing error stripes, namely the azimuth direction of the SAR image, are distributed in parallel to the columns of the image, if not, transposing the image;
(2) A subband spacing D is determined.
The implementation condition of this step is that the input image is required to be an amplitude image or a power image.
In this embodiment, the subband direction is parallel to the column, transposition is not required, the subband interval D only needs one approximate range, and D =3000 is selected in this embodiment;
step two: blocking processing for large-size images;
checking the size of the image, wherein if the length of the image exceeds a threshold value, the original algorithm mathematical model cannot accurately fit sub-band splicing error distribution in the image, if the model is directly applied to suppress the sub-band splicing effect, artificial artifacts are generated in a processing result, but the mathematical model still has good fitting performance on local images, and therefore the image needs to be blocked; if the image size is small, the mathematical model of the original algorithm can better fit the sub-band splicing error distribution in the image, and the step of image blocking is not needed, and the step four is directly performed.
The method comprises the following three steps:
(1) Calculating the image size: length × width = M × N, i.e., the image has M rows and N columns;
(2) Judging whether the block division is needed, if M <2000, directly entering the step S4; if M is greater than 2000, the image needs to be subjected to blocking processing;
(3) The reason why the columns of the image are divided is that:
in the prior art, the mathematical model of the original additive model algorithm for the sub-band splicing error of each column of pixels in the image is as follows:
I S (m)＝I O (m)+o S m∈1,M
whereinI O (m) and I S (M) the ideal and actual values for the mth pixel in the column of images, and o if the image is large, i.e. M is large S Can not be regarded as a constant, so that the image needs to be segmented, so that the model has better fitting performance.
In the present invention, the image blocking method is as follows:
actual number of divided blocks s:
s＝Floor(M/1000)
wherein, floor () is a rounding-down function, if MOD (M/1000) =0, the division result is s image blocks with 1000 × N size, and if MOD (M/1000) = x, the division result is s-1 image blocks with 1000 × N size and one image block with (1000 + x) × N size.
In this embodiment, a scan-mode synthetic aperture radar image of 18742 × 12776 is processed, M =18742, n =12776, and M >2000, so that a blocking process is required to obtain 18 sub-images, and a schematic blocking diagram of the image and an image blocking result are shown in fig. 2.
Step three: parallel processing of sub image blocks;
and step two, obtaining s image blocks after the blocking step, wherein the sub-band splicing effect suppression operation aiming at each image block is mutually independent, so that parallel processing can be carried out, and then the image blocks are spliced into a complete image to obtain a final processing result.
Therefore, in the step two, distributed parallel computation is performed on the plurality of sub-image blocks generated in the step two, and finally, the sub-image blocks are re-spliced to obtain a final sub-band splicing effect suppression result.
The method comprises the following four steps:
(1) Determining the corresponding index position of the image block in the original image, and calculating the original Mean value [ Mean _1, mean _2, \8230 ], mean _ s ] of each image block so as to facilitate image splicing after processing;
(2) Respectively carrying out sub-band splicing effect suppression on the image blocks by using a sub-band splicing effect processing algorithm based on Kalman filtering on the s image blocks, and equally dividing a calculation task to available calculation nodes for distributed parallel calculation; the sub-band splicing effect processing steps based on Kalman filtering are as follows:
a) Calculating mean and variance var of a neighborhood region of a current column, and estimating a sub-band splicing error o corresponding to each column of pixels of the image block by using a Kalman filter by taking mean and var as parameters according to a mathematical model of the sub-band splicing error S 。
b) And (5) correcting the sub-band splicing error, and directly subtracting the sub-band splicing error corresponding to a column from the column in the original image to obtain a sub-band splicing inhibition result.
c) And (3) sequentially carrying out the steps a) and b) one by one until the whole image is processed, and obtaining a sub-band splicing inhibition result.
(3) Performing mean correction on the s image blocks to ensure that the spliced positions of the image blocks do not have brightness jump; the mean correction method is as follows:
wherein I output_ x (m, n) and I' output_ x (m, n) is the pixel value of the (m, n) position in the x image block after sub-band splicing effect suppression and the x image block after Mean value adjustment respectively, mean _ x is the original Mean value of the x image block, and Output _ x _ Mean is the Mean value of the x image block after sub-band splicing effect suppression;
(4) And re-splicing the s image blocks according to the index positions to obtain a final processing result.
In this embodiment, a computing architecture based on Hadoop is adopted for distributed computing, a computing process is shown in fig. 3, data to be processed is uploaded to an HDFS during implementation, and then output data is a sub-image block to be processed in a form of < key, value >, where key is a position index corresponding to the image block and value corresponds to the image block to be processed; and (3) the Mapper acquires < key, value > data to be processed, sub-band splicing effect suppression based on Kalman filtering in the step (2) is carried out, then processing results are output in a < key, value > form, finally the mean value of the image is adjusted in the reduce process, and then splicing is carried out according to the index position, so that the processing result of the whole image is finally obtained.
Step four: parallelization calculation of sub-band splicing error estimation;
this step includes four parts:
(1) If the image does not need to be blocked, sub-band splicing effect processing based on the Kalman filter is directly carried out, and the sub-band splicing error estimation steps of each column of pixels of the Kalman filter have better independence, so that the steps of the algorithm can be modified, and then the sub-band splicing error estimation can be subjected to parallelization distributed computation, so that the processing efficiency of the sub-band splicing effect is improved.
(2) Calculating parameters required by a Kalman filter;
in the process of using the Kalman filter to estimate the sub-band error, the input of the Kalman filter mainly comprises the mean value and the variance of the left and right neighborhoods of the current estimation column and the observed value of the current column. The observed value of the current column is the difference between the pixel value of the column of the image and the mean value of the neighborhood, so that the input parameters to be estimated by using the Kalman filter only comprise the mean value and the variance of the left neighborhood and the right neighborhood. In order to make the operation for each column of pixels completely independent, the calculation of input parameters is completed before the distributed parallel calculation is performed, and the neighborhood mean and the neighborhood variance parameters corresponding to each column of pixels are stored into the M +1 th row and the M +2 nd row of each column, and at this time, each column of data of the image matrix comprises the original pixels, the neighborhood mean and the neighborhood variance of the image.
The method for calculating the domain mean and the domain variance comprises the following steps: if the current column is the ith column, calculating an image from
Is listed in
And the mean and the variance of the area corresponding to the column are the neighborhood mean and the neighborhood variance of the ith column.
(3) Distributing current image matrix data to a computing node, and performing sub-band splicing error estimation based on a Kalman filter to obtain a sub-band splicing error estimation result obtained by each column of the image;
(4) And correcting the original image according to the sub-band splicing error estimation result to obtain a final processing result.
In this embodiment, the image is processed in blocks, and parallel computation of each column is not involved. The step in the present invention may also be calculated based on a Hadoop architecture, and the flowchart is shown in fig. 4, and similarly outputs the data to be processed in the form of < key, value >, where key is the position index of the current column in the image, and value is the vector formed by the pixel values of the current column and the neighborhood mean neighborhood variance corresponding to the current column. Then, mapper obtains < key, value > data to be processed, and estimates the sub-band stitching error in the column of pixels by using a kalman filter, and the obtained estimation result is delivered in the form of < key, value >, at this time, key is the position index of the current column in the image, and value is the sub-band stitching error of the current column. And then executing a Reduce process, and correcting the sub-band splicing error in the original image according to the index position so as to obtain a final processing result.
And finishing the processing of the image sub-band splicing effect after the steps.
Examples
To illustrate the effectiveness of the present invention for algorithmic improvement, the following experiment was performed using a scan pattern synthetic aperture radar image of size 18742 × 12776 (as shown in fig. 5) that includes the sub-band stitching effect. First, the original algorithm is used, and the block processing is not performed on it, and the obtained result is shown in fig. 6. Then, the result of processing using the method of image blocking processing for a large-size image mentioned in the present invention is shown in fig. 7. The detail magnification comparison results of the two images are shown in fig. 8.
As can be seen from fig. 5, there are significant brightness fluctuations at 3 at the location of the sub-band splice in the image. After the sub-band splicing effect suppression method based on the kalman filter is used for processing, as shown in fig. 6, brightness fluctuation in the image is corrected, however, due to the defect of the algorithm model, a plurality of obvious bright lines appear in the image, which is called artificial artifacts. In fig. 7, it is clearly seen that the sub-band stitching effect in the image is well corrected and no artifacts occur. Fig. 8 shows some details of the processing result in an enlarged manner, and it can be seen that the adverse effect of the modeling defect of the sub-band splicing effect of the original algorithm on the processing result can be effectively weakened after the blocking processing is performed, and new errors cannot be brought to the image by the splicing of the subsequent sub-images in the processing step.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Those not described in detail in this specification are within the skill of the art.
Claims (9)
1. A parallelized processing method for sub-band splicing effect of synthetic aperture radar images is characterized by comprising the following steps: the method comprises the following steps:
s1, reading in an image, and preprocessing the image to obtain an image to be processed;
s2, blocking processing is conducted on the large-size image;
s3, parallelly processing the sub-image blocks subjected to the blocking step;
the specific steps of step S3 are as follows:
s31, determining corresponding index positions of image blocks in an original image, and calculating an original Mean value [ Mean _1, mean _2,. Means _ S ] of each image block so as to facilitate image splicing after processing;
s32, respectively carrying out sub-band splicing effect suppression on the image blocks by using a sub-band splicing effect processing algorithm based on Kalman filtering on the S image blocks, and equally dividing computing tasks to available computing nodes for distributed parallel computing;
s33, mean value correction is carried out on the S image blocks to ensure that brightness jump does not occur at the spliced positions of the image blocks after splicing, and the mean value correction method comprises the following steps:
in which I output_x (m, n) and I' output_x (m, n) are respectively the pixel values at (m, n) positions in the x image block after sub-band splicing effect suppression and the x image block after Mean value adjustment, mean _ x is the original Mean value of the x image block, and Output _ x _ Mean is the Mean value of the x image block after sub-band splicing effect suppression;
s34, splicing the S image blocks again according to the index positions to obtain a final processing result;
and S4, calculating and estimating the sub-band splicing error in a parallelization mode.
2. The method for processing the sub-band stitching effect of the parallelized synthetic aperture radar image according to claim 1, wherein: the specific steps of step S1 are as follows:
s11, judging the stripe direction in the image, specifically judging whether sub-band splicing error stripes, namely the azimuth direction of the SAR image, are parallel to the longitudinally arranged column distribution of the image, and if not, transposing the image;
and S12, determining a sub-band interval D.
3. The parallelized method for processing the sub-band stitching effect of the synthetic aperture radar image according to claim 2, characterized in that: the specific steps of step S2 are as follows:
s21, calculating the image size: length × width = M × N, i.e., the image has M rows and N columns;
s22, judging whether the block division is needed or not, and if M is less than 2000, directly entering the step S4; if M is greater than 2000, the image needs to be subjected to blocking processing;
s23, dividing the columns of the image, wherein the image blocking method comprises the following steps:
actual number of divided blocks s:
s＝Floor(M/1000)，
the Floor () is a rounding-down function, and if MOD (M/1000) =0, the division result is s image blocks of 1000 × N size, and if MOD (M/1000) = x, the division result is s-1 image blocks of 1000 × N size and one image block of (1000 + x) × N size.
4. The parallelized SAR image sub-band stitching effect processing method according to claim 3, characterized in that: the specific steps of step S32 are as follows:
s321, calculating the mean and the variance var of the neighborhood region of the current column, and then estimating the sub-band splicing error o corresponding to each column of pixels of the image block by using a Kalman filter by taking the mean and the variance var as parameters according to the additive model of the sub-band splicing error S ；
S322, sub-band splicing error correction is carried out, and sub-band splicing errors corresponding to a row are directly subtracted from the row in the original image to obtain a sub-band splicing inhibition result;
and S323, sequentially performing the steps S321 and S322 line by line until the whole image is processed, and obtaining a sub-band splicing inhibition result.
5. The parallelized SAR image sub-band stitching effect processing method according to claim 4, characterized in that: the specific steps of step S4 are as follows:
s41, if the image does not need to be blocked, directly carrying out sub-band splicing effect processing based on a Kalman filter;
s42, if the image is the image after the block division, calculating parameters required by a Kalman filter;
s43, distributing the current image matrix data calculated in the step S42 to a calculation node, and performing sub-band splicing error estimation based on a Kalman filter to obtain a sub-band splicing error estimation result obtained by each column of the image;
and S44, correcting the original image according to the sub-band splicing error estimation result to obtain a final processing result, namely finishing sub-band splicing effect suppression of the image.
6. The method according to claim 5, wherein the method comprises the following steps: the specific process of step S42 is as follows:
s421, when a Kalman filter is used for sub-band error estimation, the calculation of input parameters is completed before distributed parallel calculation, the input parameters of the Kalman filter comprise the mean value of the left and right neighborhoods of the current estimation column, the variance of the left and right neighborhoods of the current estimation column and the observed value of the current column, wherein the calculation method of the domain mean value and the domain variance comprises the following steps: if the current column is the ith column, calculating an image from
Is listed to
The mean value and the variance of the area corresponding to the column are the neighborhood mean value and the neighborhood variance of the ith column;
s422, storing neighborhood mean values and neighborhood variance parameters corresponding to each row of pixels into the M +1 th row and the M +2 th row of each row, wherein each row of data of the image matrix comprises original pixels of the image, the neighborhood mean values and the neighborhood variances.
7. The method according to claim 6, wherein the method comprises the following steps: in step S12, the subband splicing error stripe direction is parallel to the column, and the subband interval D =3000;
in step S2, M =18742, n =12776, and M >2000, it is necessary to perform a blocking process to obtain 18 sub-images.
8. The method according to claim 7, wherein the method comprises the following steps: the distributed computation of the step S3 adopts a computation framework based on Hadoop, and the implementation steps are as follows: uploading data to be processed to an HDFS (Hadoop distributed File System), and then outputting data to be sub image blocks to be processed in a form of < key, value >, wherein the key is a position index corresponding to the image block, and the value corresponds to the image block to be processed; the Mapper acquires < key, value > data to be processed, performs sub-band splicing effect suppression based on Kalman filtering in step 32, outputs a processing result in the form of < key, value >, adjusts the mean value of the image in the reduce process, and performs splicing according to the index position to obtain the processing result of the whole image.
9. The parallelized method for processing the sub-band stitching effect of the synthetic aperture radar image according to claim 8, characterized in that: the step S4 is based on a Hadoop framework to calculate, and the data to be processed is output in a form of < key, value >, wherein the key is a position index of a current column in an image, and the value is a vector formed by pixel values of the current column and neighborhood mean neighborhood variance corresponding to the current column; then, the Mapper acquires < key, value > data to be processed, a Kalman filter is used for estimating sub-band splicing errors in the column of pixels, the obtained estimation result is transmitted in a form of < key, value >, at the moment, key is the position index of the current column in the image, and value is the sub-band splicing error of the current column; and then, executing Reduce process, and correcting the sub-band splicing error in the original image according to the index position, thereby obtaining a final processing result, namely finishing the processing of the image sub-band splicing effect.
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