CN108022220A - A kind of ultrasound pattern speckle noise minimizing technology - Google Patents

A kind of ultrasound pattern speckle noise minimizing technology Download PDF

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CN108022220A
CN108022220A CN201711275034.1A CN201711275034A CN108022220A CN 108022220 A CN108022220 A CN 108022220A CN 201711275034 A CN201711275034 A CN 201711275034A CN 108022220 A CN108022220 A CN 108022220A
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周颖玥
臧红彬
方宏道
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Southwest University of Science and Technology
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    • G06COMPUTING; CALCULATING OR COUNTING
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    • G06T2207/10Image acquisition modality
    • G06T2207/10072Tomographic images
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Abstract

The invention discloses a kind of ultrasound pattern speckle noise minimizing technology, and in iteration first, by the use of noise image as the input of model, a coarse despeckle image has been obtained after the filtering of bayesian non-local average filter model;In second of iteration, the input using acquired despeckle image as Filtering Model, obtains the more preferable despeckle image of a width;Iteration process, untill iterations reaches default value.Pass through the benign preferable despeckle image of one width of iterative filtering process final output.The advantage of the invention is that:The harmful effect for inhibiting speckle noise to be brought to clinical diagnosis or successive image processing.With reference to the statistical property of speckle noise, the conditional probability density function value in bayesian non-local average filter model is extrapolated, preferable despeckle image will be exported by benign iterative filtering process.In order to reduce the time complexity of algorithm, filtered using block, preselect block and control three kinds of means of iterations so that method can be practical.

Description

A kind of ultrasound pattern speckle noise minimizing technology
Technical field
The present invention relates to ultrasonoscopy processing technology field, more particularly to a kind of ultrasound pattern speckle noise minimizing technology.
Background technology
Ultrasonic imaging technique is a kind of conveniently imaging technique, is widely used among human body inspection, especially It is the positions such as liver, courage, pancreas, abdomen, mammary gland.Compared with CT imaging techniques, ultrasonic imaging is much more secure, eliminates human body and is exposed to Radiation injury caused by lower of X-ray is possible;Compared with MRI imaging techniques, the expense of ultrasonic imaging is much lower, be physical examination or The important image mode of first run disorder in screening.However, the image acquired in ultrasonic instrument is all inevitably subject to spot at present The interference of noise, this noise are caused by the coherence being imaged as ultrasonic system.The presence of speckle noise reduces figure The resolution ratio and contrast of picture, reduce the quality of image, mask some detailed information, to clinical diagnosis and follow-up image Processing analysis (such as:Feature extraction, lesion segmentation identification, image registration etc.) cause detrimental effect, therefore speckle noise Suppression have very important significance to medical ultrasound image analysis.It is similar with other Image Denoising Technology problems, ultrasound figure As the target of speckle noise reduction is should effectively to remove noise, retain the Key detail line in image as much as possible again Manage feature.But speckle noise has certain difference with the Gaussian noise considered in usual image denoising problem, from the perspective of morphology It appear that graininess or the effect of snake mark, its noise generation model is different from additive Gaussian from noise statistics White noise, therefore directly existing denoising method can not be moved in the elimination of speckle noise, but need in denoising model On fully take into account the characteristic of speckle noise, improve existing model, give full play to existing noise-removed technology on speckle noise reduction Effect.
The content of the invention
The defects of present invention is directed to the prior art, there is provided a kind of ultrasound pattern speckle noise minimizing technology, can be effective Solve the above-mentioned problems of the prior art.
In order to realize above goal of the invention, the technical solution that the present invention takes is as follows:
A kind of ultrasound pattern speckle noise minimizing technology, comprises the following steps that:
Step 1:
It is based on
In above formula, z is exactly the image containing speckle noise that B ultrasound instrument is obtained,It is the clean image of estimation, i is figure The coordinate position of pixel in the Ω of image space;Δ (i) is represented centered on coordinate points i, size is the neighborhood search region of β × β, is sat Punctuate j belongs in Δ (i);Z (j) represent centered on pixel j in image z, size for α × α image block;Z (i) represent with In image z centered on pixel i, the image block that size is α × α;P (z (i) | z (j)) in observation figure below of image block z (j) The conditional probability density function value of picture block z (i),For in image blockObservation hypograph block z (i) bar Part probability density function values;Represent estimating without spot for the image block centered on i;Estimated allAverage fusion is carried out, obtains despeckle image
Above formula implication is:In first step filtering, directly using noise image z as input, put down by the weighting of image block Equal and combination can obtain the rough estimate to no spot image;Then, the input then using the estimation image filtered as next step, Thus filter result is corrected;
According to formula 1 calculate p (z (i) | z (j)) under speckle noise environment andIt can be gone Spot image, due toThe Gaussian noise that wherein n (i) is zero-mean, standard deviation is σ distributions, therefore Z (i) | u (i)~N (u (i), u (i) σ2), then
Step 2:
In view of in image block pixel conditional sampling it is assumed that the probability distribution situation of image block can be obtained:
In above formula | R | represent image number of pixels in the block, r represents image r-th of pixel in the block.Based on formula 2, formula 1 P (z (i) | z (j)) in the first step may be calculated:
And in second stepIt can be calculated as:
Step 3:
In order to further lift despeckle performance, iterations is expanded to K times, (2≤K≤4), then complete iterative filtering Despeckle model is shown below:
Preferably, the value of the h of adjustable type 5 is to obtain best despeckle effect in the step 3, due to h and σ2Correlation, We make h=(C σ)2, summarized through many experiments, as C=1, despeckle effect is best.Can not be in the case of known σ, h takes It is worth for 8 best results.
Preferably, the degree of overlapping between adjustment image block, reduces time complexity.
Preferably, block pre-selection mechanism is added in filtering, when the average and target image block that find the block in neighborhood are equal When value difference is too big, then without considering contribution of the image block to object block estimate, i.e.,:
Default block average value threshold value is set to μ, makes μ=0.7;
WhenDuring beyond [μ, 1/ μ] scope, then willBlock pairContribution be set to 0.
Preferably, scope of the iterations K controls 2 to 4, and as speckle noise degree σ increases, K gradually drop For 2, the time complexity that less iterations controls algorithm increases.
Compared with prior art the advantage of the invention is that:Largely inhibit speckle noise to clinical diagnosis or The harmful effect that successive image processing is brought., will be defeated by benign iterative filtering process with reference to the statistical property of speckle noise Go out preferable despeckle image.Meanwhile in order to reduce the time complexity of algorithm to greatest extent, filtered using block, preselect block and Control three kinds of means of iterations so that method can be practical.
Brief description of the drawings
Fig. 1 is the middle despeckle that head noise phantom image (σ=10) and the method for the present invention produce in an iterative process Figure;
Fig. 1 a are head noise phantom image (σ=10);
Fig. 1 b are the result images after carried algorithm first time iteration
Fig. 1 c are the result images after carried second of iteration of algorithm
Fig. 1 d are the result images after carried algorithm third time iteration
Fig. 1 e are clean head phantom image;
Fig. 2 is despeckle result figure of the different despeckle algorithms to the head noise phantom image of σ=10;
Fig. 2 a are head noise phantom image (σ=10);
Fig. 2 b are the despeckle result figure of SRAD;
Fig. 2 c are the despeckle result figure of SRBF;
Fig. 2 d are the despeckle result figure of TBNLMF;
Fig. 2 e are the despeckle result figure of OBNLMF;
Fig. 2 f put forward the despeckle result figure of algorithm for us;
Fig. 2 g are clean head phantom image;
Fig. 3 is emulation ultrasonic fetal image and despeckle image;
Fig. 3 a are the emulation ultrasonic fetal image of Field II Simulation Program generations;
Despeckle images of Fig. 3 b for carried algorithm to Fig. 3 a;
Fig. 4 is live ultrasound image and despeckle image;
Fig. 4 a are live ultrasound image;
The despeckle image that Fig. 4 b produce for carried algorithm.
Embodiment
For the objects, technical solutions and advantages of the present invention are more clearly understood, develop simultaneously embodiment referring to the drawings, right The present invention is described in further details.
In traditional sense, speckle noise is considered as the multiplying property signal model of Rayleigh distributed, yet with image-forming mechanism Complexity, this model be not suitable for true speckle noise model.It is more suitable in recent years, some scholars propose one kind Speckle noise model, it is as follows:
Z (i)=u (i)+uγ(i)n(i). (1)
In above formula, z is exactly the image containing speckle noise that B ultrasound instrument is obtained, and u is it is desirable that what is recovered is clean Image, the Gaussian noise that n is obedience zero-mean, standard deviation is σ distributions, i is the coordinate position of pixel in image space Ω, and γ is With the relevant parameter of ultrasonic instrument, γ=0.5 is usually taken.From formula (1) as can be seen that speckle noise and additive Gaussian noise are not With, it is impossible to algorithm directly is removed to handle speckle noise using Gaussian noise, it is necessary to fully takes into account the statistical property of noise To change algorithm to adapt to speckle noise environment.
It is non local average filter under non-Gaussian noise environment according to a kind of bayesian non-local average filter model Using providing possibility.The model is as follows:
Here, u (j) represent centered on pixel j in image u, size for α × α image block;Z (i) is represented with image In z centered on pixel i, the image block that size is α × α;Δ (i) represent centered on coordinate points i, size for β × β neighborhood Region of search, coordinate points j belong in Δ (i);Represent estimating without spot for the image block centered on i.By all estimations Go out(i ∈ Ω) carries out average fusion, obtains despeckle imageIn fact, this is a kind of noise based on image block On filtering mode, with classical block-based non local average filter model form unanimously.
No spot image u is needed in apparent formula (2), and as inputting, this can not accomplish, therefore in order to realize the mould Type, it is thus proposed that a kind of two step iterative models, by the process progressively to become more meticulous dexterously solve the problems, such as this:
The implication that above formula represents as:In first step filtering, directly using noise image z as input, it can obtain to nothing The rough estimate of spot image;Then, the input then using the estimation image filtered as next step, thus corrects filter result.
Then, the speckle noise in ultrasonoscopy is removed using the model corresponding to formula (2), is made an uproar according to spot The statistical property of sound is deduced the probability density function needed for model, obtains good despeckle effect.However, realizing shellfish During the non local average filter models of Ye Si, existing classical documents eliminate follow-up the step of becoming more meticulous, and obtain despeckle image and compare It is coarse.For this problem, this patent proposes a kind of ultrasound pattern speckle noise minimizing technology, specific as follows:
Based on model (3), we need to only calculate p (z (i) | z (j)) under speckle noise environment andIt can obtain despeckle image.Due toTherefore z (i) | u (i)~N (u (i), u(i)σ2), then
In view of in image block pixel conditional sampling it is assumed that the probability distribution situation of image block can be obtained:
In above formula | R | represent image number of pixels in the block, r represents image r-th of pixel in the block.Based on (4), model (3) p in the first step (z (i) | z (j)) may be calculated:
And in second stepIt can be calculated as:
In addition, in order to further lift despeckle performance, iterations is expanded to K times (2≤K≤4) by us, then completely Iterative filtering despeckle model is as follows:
Notice that we instead of 2 σ with variable h in above formula2, in an experiment we adjust the value of h to obtain best despeckle Effect.Final gainedAs exportDue to h and σ2Correlation, we make h=(C σ)2, summarized through many experiments, As C=1, despeckle effect is best.Can not be in the case of known σ, h values be 8 best results.
In order to reduce the time complexity of Iterative-Filtering Scheme, this patent uses following three key processing mode:
(1) from formula (7) as can be seen that despeckle algorithm needs iteration K time, thus filter each time cannot spend it is too many Time, otherwise the when consumption of algorithm is just long.In fact, the filter patterns based on image block can be by adjusting between image block (the distance between adjacent image block center in other words, is set to d) consume during its filtering effectively to control degree of overlapping.According to pertinent literature Analysis [12] understand:The time complexity of block-based non local average filter algorithm is O ((2 α+1)2(2β+1)2((N-d)/ d)2), N is the length of side of image here.If as it can be seen that the distance between image block d is arranged to 3, then it can make what is once filtered Time shortens 9 times or so when than d being 1, and despeckle performance there will not be too big difference.Iteration K times, then can save 9K times Time.
(2) block pre-selection mechanism is added in filtering, when the average for finding the block in neighborhood is differed with target image block average , then can be without considering contribution of the image block to object block estimate, i.e., when too big:During beyond [μ, 1/ μ] scope (μ is default block average value threshold value, usually makes μ=0.7), then willBlock pairContribution be set to 0, so not only shorten It is corresponding to calculate the time, it also avoid harmful effect of the cumulative errors to finally estimating.
(3) scope of the iterations K controls 2 to 4, and as speckle noise degree σ increases, K are gradually reduced to 2, compared with The time complexity that few iterations controls algorithm increases.
Experiment and interpretation of result:
In order to test the performance of put forward despeckle algorithm, we have chosen three kinds of test images, the first is according to being assumed Noise model and the speckle noise image simulated, be for second analog simulation ultrasonoscopy, the third is straight from B ultrasound instrument The real ultrasonoscopy obtained.Meanwhile have chosen several representational despeckle algorithms and contrasted with carried algorithm, they It is respectively:SRAD,SRBF,traditional blockwise NLMF(TBNLMF),OBNLMF.For proposed by the invention Iterative-Filtering Scheme, it is in order to obtain preferable despeckle effect, parameter setting is as follows:The range delta (i) of non local neighborhood is set For 19 × 19;Image block is dimensioned to 5 × 5;As σ < 10, iterations K is set to 4, the K=3 as 10≤σ < 20, when K=2 during σ >=20;H is arranged to σ in Filtering Model2;In addition, when σ is unknown, the value of h will be adjusted according to actual conditions, and In view of conveniently factor, K is then set to 2.We verify the advantage of put forward algorithm by three groups of different experiments below.
Head noise phantom image experiment:
The head phantom image of several different noise levels is generated using the speckle noise modeling of hypothesis, for These test images, due to the known corresponding clean image of immaculate, can use " full reference image quality appraisement index " Quantitatively evaluating is done come the quality of the recovery image exported to algorithms of different.Here the index used is Y-PSNR (Peak Signal-to-Noise Ratio, PSNR) and characteristic similarity Index (Feature Similarity Index Measure, FSIM).The calculating formula of PSNR is:
Wherein MN is the size of image, FSIM is the image quality evaluation index developed in recent years, wherein image Phase equalization and gradient amplitude are used for the difference for weighing image pair,.When recovery imageDuring closer to clean image u, The value of FSIM is closer to 1.
First, in order to test the correctness of put forward iterative algorithm, we devise following experiment.In different noise levels Under, caused recovery image in iterative process is all recorded, is denoted as respectivelyIt is right that its is calculated again PSNR the and FSIM values answered, experimental result are as shown in table 1.Runic data in table are represented per the best restoration result value of a line. There it can be seen that under any σ,Certainly ratioIt is better, and when σ is smaller, with the increase of iterations K,It can get over It is better to come, this fully demonstrates the correctness of put forward iterative filtering despeckle algorithm.Meanwhile we illustrate propose calculation in Fig. 1 Produced during the head noise phantom image of method processing σ=10See each time with being apparent from Makeover process of the iteration to recovery image.
Table 1 carries the middle denoising result (PSNRs, FSIMs) of iterative algorithm when handling " head noise phantom image "
Then, the head noise phantom image of different noise levels is input in selected despeckle algorithm by we, is obtained Different despeckle images has been arrived, has calculated itself PSNR and FSIM value, the results are shown in Table 2.Equally, the runic data in table represent every The best restoration result value of a line.As can be seen that carried algorithm is optimal under the picture quality deliberated index of PSNR and FSIM Algorithm.Meanwhile we illustrate despeckle result figure of each algorithm to the head noise phantom image of σ=10 in fig. 2, from regarding It can be seen that in feel:SRAD algorithms are stronger to the holding capacity of details, but many spots have still been retained in despeckle image;SRBF Despeckle image in have the presence of many artifacts;TBNLMF algorithms can remove most spots, but lost many details Feature;OBNLMF can keep reaching certain balance in blotch removal and details, but noise is still remained in image background Trace;And the algorithm that we are proposed can not only remove most noises, while also done in the holding at details and edge Obtain preferably.
The different despeckle algorithms of table 2 to the despeckle result of the head noise phantom image of different noise levels (PSNRs, FSIMs)
The ultrasonoscopy experiment that Field II Simulation Program simulations produce:
Field II Simulation Program are that the ultrasonoscopy researched and developed according to ultrasonic imaging principle emulates generation Program, has higher reference value.In the experiment of this section, we have chosen by Field II Simulation " fetus " image of Program emulation generations, as our test image, as shown in Figure 3a.Then us are entered into (pay attention in the despeckle algorithm proposed:Due to the information of no σ, 12) h in Filtering Model is set to, and the despeckle image of output is such as Shown in Fig. 3 b.Two images are contrasted, we can become apparent from:Most speckle noises have been removed in right figure, together When anatomical structure still complete display, this has absolutely proved the validity for carrying despeckle algorithm.
Live ultrasound image is tested:
The verification tested by first two, we have affirmed the validity for carrying algorithm, using true in the experiment of this section Real ultrasonoscopy is as test object, as shown in fig. 4 a.Then recycle carry algorithm to the operation of carry out despeckle (attention: In order to retain details as much as possible while despeckle, 8) h in Filtering Model is set to, gained image is as shown in Figure 4 b.From Figure can be seen that:Despeckle image not remove only speckle noise, and the edge between adjacent anatomical structures is kept as very well, This undoubtedly has very big benefit for the diagnosis of diagnostic imaging teacher.Certainly, to note here is that:Generally for medical image For processing, we term it " computer-aided diagnosis ", doctor wishes that the image after combining artwork and handling is made jointly Diagnostic result, rather than referring only to the figure after processing, because any type signal processing mode all can more or less lose The potential minutia of signal, image contrast is with reference to so that diagnosis is more accurate.
Those of ordinary skill in the art will understand that the embodiments described herein, which is to help reader, understands this hair Bright implementation, it should be understood that protection scope of the present invention is not limited to such special statement and embodiment.Ability The those of ordinary skill in domain can according to the present invention these disclosed technical inspirations make it is various do not depart from essence of the invention its Its various specific deformations and combination, these deformations and combination are still within the scope of the present invention.

Claims (5)

1. a kind of ultrasound pattern speckle noise minimizing technology, it is characterised in that comprise the following steps that:
Step 1:
It is based on
In above formula, z is exactly the image containing speckle noise that B ultrasound instrument is obtained,It is the clean image of estimation, i is image sky Between in Ω pixel coordinate position;Δ (i) is represented centered on coordinate points i, size is the neighborhood search region of β × β, coordinate points J belongs in Δ (i);Z (j) represent centered on pixel j in image z, size for α × α image block;Z (i) is represented with image In z centered on pixel i, the image block that size is α × α;P (z (i) | z (j)) in the observation hypograph block z of image block z (j) (i) conditional probability density function value,For in image blockObservation hypograph block z (i) condition it is general Rate density function values; Represent estimating without spot for the image block centered on i;Estimated allAverage fusion is carried out, obtains despeckle image
Above formula implication is:In first step filtering, directly using noise image z as inputting, by the weighted average of image block and Combination can obtain the rough estimate to no spot image;Then, the input then using the estimation image filtered as next step, thus Correct filter result;
According to formula 1 calculate p (z (i) | z (j)) under speckle noise environment andIt can obtain despeckle figure Picture, due toThe Gaussian noise that wherein n (i) is zero-mean, standard deviation is σ distributions, therefore z (i) | u (i)~N (u (i), u (i) σ2), then
Step 2:
In view of in image block pixel conditional sampling it is assumed that the probability distribution situation of image block can be obtained:
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In above formula | R | represent image number of pixels in the block, r represents image r-th of pixel in the block, based on formula 2, formula 1 first P (z (i) | z (j)) in step may be calculated:
<mrow> <mi>p</mi> <mrow> <mo>(</mo> <mi>z</mi> <mo>(</mo> <mi>i</mi> <mo>)</mo> <mo>|</mo> <mi>z</mi> <mo>(</mo> <mi>j</mi> <mo>)</mo> <mo>)</mo> </mrow> <mo>=</mo> <mi>exp</mi> <mrow> <mo>(</mo> <mo>-</mo> <msubsup> <mo>&amp;Sigma;</mo> <mrow> <mi>r</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mo>|</mo> <mi>R</mi> <mo>|</mo> </mrow> </msubsup> <mfrac> <msup> <mrow> <mo>(</mo> <msup> <mi>z</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mo>(</mo> <mi>i</mi> <mo>)</mo> <mo>-</mo> <msup> <mi>z</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mo>(</mo> <mi>j</mi> <mo>)</mo> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mrow> <mn>2</mn> <msup> <mi>z</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mrow> <mo>(</mo> <mi>j</mi> <mo>)</mo> </mrow> <msup> <mi>&amp;sigma;</mi> <mn>2</mn> </msup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>.</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>3</mn> <mo>)</mo> </mrow> </mrow>
And in second stepIt can be calculated as:
<mrow> <mi>p</mi> <mrow> <mo>(</mo> <mi>z</mi> <mo>(</mo> <mi>i</mi> <mo>)</mo> <mo>|</mo> <mover> <mi>u</mi> <mo>^</mo> </mover> <mo>(</mo> <mi>j</mi> <mo>)</mo> <mo>)</mo> </mrow> <mo>=</mo> <mi>exp</mi> <mrow> <mo>(</mo> <mo>-</mo> <msubsup> <mo>&amp;Sigma;</mo> <mrow> <mi>r</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mo>|</mo> <mi>R</mi> <mo>|</mo> </mrow> </msubsup> <mfrac> <msup> <mrow> <mo>(</mo> <msup> <mi>z</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mo>(</mo> <mi>i</mi> <mo>)</mo> <mo>-</mo> <msup> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mo>(</mo> <mi>j</mi> <mo>)</mo> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mrow> <mn>2</mn> <msup> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mrow> <mo>(</mo> <mi>j</mi> <mo>)</mo> </mrow> <msup> <mi>&amp;sigma;</mi> <mn>2</mn> </msup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>.</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>4</mn> <mo>)</mo> </mrow> </mrow>
Step 3:
In order to further lift despeckle performance, iterations is expanded to K times, (2≤K≤4), then complete iterative filtering despeckle Model is shown below:
<mrow> <mtable> <mtr> <mtd> <mrow> <mi>I</mi> <mi>n</mi> <mi>i</mi> <mi>t</mi> <mi>i</mi> <mi>a</mi> <mi>l</mi> <mi>i</mi> <mi>z</mi> <mi>e</mi> <mo>:</mo> <mi>k</mi> <mo>=</mo> <mn>1.</mn> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mi>W</mi> <mi>h</mi> <mi>i</mi> <mi>l</mi> <mi>e</mi> <mrow> <mo>(</mo> <mi>k</mi> <mo>&amp;le;</mo> <mi>K</mi> <mo>)</mo> </mrow> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mi>i</mi> <mi>f</mi> <mrow> <mo>(</mo> <mi>k</mi> <mo>=</mo> <mo>=</mo> <mn>1</mn> <mo>)</mo> </mrow> <mo>:</mo> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mrow> <msub> <mo>&amp;Sigma;</mo> <mrow> <mi>j</mi> <mo>&amp;Element;</mo> <mi>&amp;Delta;</mi> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> </mrow> </msub> <mi>z</mi> <mrow> <mo>(</mo> <mi>j</mi> <mo>)</mo> </mrow> <mo>&amp;CenterDot;</mo> <mi>exp</mi> <mrow> <mo>(</mo> <mo>-</mo> <msubsup> <mo>&amp;Sigma;</mo> <mrow> <mi>r</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mo>|</mo> <mi>R</mi> <mo>|</mo> </mrow> </msubsup> <msup> <mrow> <mo>(</mo> <mrow> <msup> <mi>z</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>-</mo> <msup> <mi>z</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mrow> <mo>(</mo> <mi>j</mi> <mo>)</mo> </mrow> </mrow> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>/</mo> <msup> <mi>hz</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mo>(</mo> <mi>j</mi> <mo>)</mo> <mo>)</mo> </mrow> </mrow> <mrow> <msub> <mo>&amp;Sigma;</mo> <mrow> <mi>j</mi> <mo>&amp;Element;</mo> <mi>&amp;Delta;</mi> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> </mrow> </msub> <mi>exp</mi> <mrow> <mo>(</mo> <mo>-</mo> <msubsup> <mo>&amp;Sigma;</mo> <mrow> <mi>r</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mo>|</mo> <mi>R</mi> <mo>|</mo> </mrow> </msubsup> <msup> <mrow> <mo>(</mo> <mrow> <msup> <mi>z</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>-</mo> <msup> <mi>z</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mrow> <mo>(</mo> <mi>j</mi> <mo>)</mo> </mrow> </mrow> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>/</mo> <msup> <mi>hz</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mo>(</mo> <mi>j</mi> <mo>)</mo> <mo>)</mo> </mrow> </mrow> </mfrac> <mo>&amp;DoubleRightArrow;</mo> <mover> <mi>u</mi> <mo>^</mo> </mover> <mo>;</mo> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mi>k</mi> <mo>=</mo> <mi>k</mi> <mo>+</mo> <mn>1.</mn> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mi>e</mi> <mi>l</mi> <mi>s</mi> <mi>e</mi> <mo>:</mo> <mover> <mi>u</mi> <mo>~</mo> </mover> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mrow> <msub> <mo>&amp;Sigma;</mo> <mrow> <mi>j</mi> <mo>&amp;Element;</mo> <mi>&amp;Delta;</mi> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> </mrow> </msub> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mo>(</mo> <mi>j</mi> <mo>)</mo> </mrow> <mo>&amp;CenterDot;</mo> <mi>exp</mi> <mrow> <mo>(</mo> <mo>-</mo> <msubsup> <mo>&amp;Sigma;</mo> <mrow> <mi>r</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mo>|</mo> <mi>R</mi> <mo>|</mo> </mrow> </msubsup> <msup> <mrow> <mo>(</mo> <mrow> <msup> <mi>z</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>-</mo> <msup> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mrow> <mo>(</mo> <mi>j</mi> <mo>)</mo> </mrow> </mrow> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>/</mo> <mi>h</mi> <msup> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mo>(</mo> <mi>j</mi> <mo>)</mo> <mo>)</mo> </mrow> </mrow> <mrow> <msub> <mo>&amp;Sigma;</mo> <mrow> <mi>j</mi> <mo>&amp;Element;</mo> <mi>&amp;Delta;</mi> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> </mrow> </msub> <mi>exp</mi> <mrow> <mo>(</mo> <mo>-</mo> <msubsup> <mo>&amp;Sigma;</mo> <mrow> <mi>r</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mo>|</mo> <mi>R</mi> <mo>|</mo> </mrow> </msubsup> <msup> <mrow> <mo>(</mo> <mrow> <msup> <mi>z</mi> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>-</mo> <msup> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mrow> <mo>(</mo> <mi>j</mi> <mo>)</mo> </mrow> </mrow> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>/</mo> <mi>h</mi> <msup> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mo>(</mo> <mi>r</mi> <mo>)</mo> </mrow> </msup> <mo>(</mo> <mi>j</mi> <mo>)</mo> <mo>)</mo> </mrow> </mrow> </mfrac> <mo>&amp;DoubleRightArrow;</mo> <mover> <mi>u</mi> <mo>~</mo> </mover> <mo>;</mo> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mi>k</mi> <mo>=</mo> <mi>k</mi> <mo>+</mo> <mn>1</mn> <mo>;</mo> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mover> <mi>u</mi> <mo>^</mo> </mover> <mo>=</mo> <mover> <mi>u</mi> <mo>~</mo> </mover> <mo>.</mo> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>o</mi> <mi>p</mi> <mi>t</mi> </mrow> </msub> <mo>=</mo> <mover> <mi>u</mi> <mo>^</mo> </mover> <mo>.</mo> </mrow> </mtd> </mtr> </mtable> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>5</mn> <mo>)</mo> </mrow> <mo>.</mo> </mrow>
A kind of 2. ultrasound pattern speckle noise minimizing technology according to claim 1, it is characterised in that:In the step 3 The value of the h of adjustable type 5 is to obtain best despeckle effect, due to h and σ2Correlation, makes h=(C σ)2, summarized through many experiments, As C=1, despeckle effect is best, and can not be in the case of known σ, h values be 8 best results.
A kind of 3. ultrasound pattern speckle noise minimizing technology according to claim 1, it is characterised in that:Adjust image block it Between degree of overlapping, reduce time complexity.
A kind of 4. ultrasound pattern speckle noise minimizing technology according to claim 1, it is characterised in that:Added in filtering Block preselects mechanism, when the average for finding the block in neighborhood differs too big with target image block average, then without considering the image block Contribution to object block estimate, i.e.,:
Default block average value threshold value is set to μ, makes μ=0.7;
WhenDuring beyond [μ, 1/ μ] scope, then willBlock pairContribution be set to 0.
A kind of 5. ultrasound pattern speckle noise minimizing technology according to claim 1, it is characterised in that:Iterations K is controlled The scope 2 to 4 is made, and as speckle noise degree σ increases, K are gradually reduced to 2, less iterations controls algorithm Time complexity increase.
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