CN110490869A - A kind of ultrasound image contrast and lateral resolution optimization method - Google Patents
A kind of ultrasound image contrast and lateral resolution optimization method Download PDFInfo
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
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Abstract
The present invention relates to a kind of ultrasound image contrast and lateral resolution optimization methods, belong to ultrasound image processing technology field, solve the problems, such as that the picture contrast of existing ultrasound image processing method acquisition and lateral resolution are poor.The optimization method is the following steps are included: obtain N width raw ultrasound echo using ultrasonic transducer；The N width raw ultrasound echo is smoothed as unit of pixel, obtains echo data matrix；Based on the echo data matrix after smoothing processing, the covariance matrix of echo-signal is calculated；White noise signal is added in the covariance matrix of echo-signal, calculates the characteristic value and feature vector of the covariance matrix of addition white noise signal；Smoothed out echo data matrix is constrained using the maximum eigenvalue of the covariance matrix of addition white noise signal, obtains final ultrasonic echo image.Step of the invention is simple, easy to operate, can significantly improve the contrast and lateral resolution of ultrasound image.
Description
Technical field
The present invention relates to ultrasound image processing technology field more particularly to a kind of ultrasound image contrasts and lateral resolution
Optimization method.
Background technique
Ultrasonic imaging has the characteristics that transmission capacity is strong, small to human injury, has become most important medical diagnosis skill
One of art.Ultrasonic imaging is to detect body using ultrasonic irradiation, by receiving and processing is loaded with detection body interior tissue or structure
The echo of characteristic information obtains the methods and techniques of the internal information of detected body tissue and structure.Ultrasonic imaging has price
It is cheap, imaging real-time it is good, to patient without infringement the advantages that.Tissue such as muscle, fat, spleen, stomach etc. has similar sound
The ultrasonic echo energy of impedance, each Tissue reflectance is close, therefore the ultrasound image of high contrast facilitates doctor and identifies different groups
Knit information.Picture contrast has become one of main performance of ultrasonic diagnostic equipment, how to improve system contrast and laterally divides
Resolution is the hot spot of current research.
Existing ultrasonograph quality optimization method is generally basede on synthetic aperture technique and realizes the transmitting of ultrasonic wave and receive poly-
Coke, although synthetic aperture technique emits in entire visual field equivalent implementation cannot reject back with focusing technology while reception
Interference signal and noise signal in wave signal, the ultrasound image secondary lobe interference still with higher after focusing, picture contrast
Difference.It is influenced by array signal focus characteristics, the side-lobe energy of ultrasound image is higher, is that suppressed sidelobes noise need to be become using amplitude
Mark technology improves the contrast of image, but can increase however, although traditional amplitude Apodization techniques are able to suppress secondary lobe interference
Big main lobe width reduces the lateral resolution of image.
To sum up, the prior art faces following challenge: (1) synthetic aperture technique obtains preferable lateral resolution, but other
Valve noise is big, poor contrast, and ultrasonograph quality is poor；(2) amplitude Apodization techniques inhibit secondary lobe to interfere, but it is wide to will cause main lobe
Degree increases, and reduces image resolution ratio.Therefore, it is badly in need of proposing a kind of picture contrast and lateral resolution of capable of improving simultaneously
Method.
Summary of the invention
In view of above-mentioned analysis, the present invention is intended to provide a kind of ultrasound image contrast and lateral resolution optimization method,
Picture contrast and lateral resolution to solve the problems, such as existing ultrasound image processing method acquisition is poor.
The purpose of the present invention is mainly achieved through the following technical solutions:
On the one hand a kind of ultrasound image contrast and lateral resolution optimization method are provided, comprising the following steps:
Step 1: obtaining N width raw ultrasound echo using ultrasonic transducer；
Step 2: the N width raw ultrasound echo being smoothed as unit of pixel, obtains number of echoes
According to matrix；
Step 3: based on the echo data matrix after smoothing processing, calculating the covariance matrix of echo-signal；
Step 4: adding white noise signal in the covariance matrix of echo-signal, calculate the association side of addition white noise signal
The characteristic value and feature vector of poor matrix；
Step 5: using the maximum eigenvalue for the covariance matrix for adding white noise signal to smoothed out echo data square
Battle array is constrained, and final ultrasonic echo image is obtained.
Further, in step 1, emit ultrasonic wave using the single array element of ultrasound transducer array, and utilize all battle arrays
Member receives ultrasonic echo, carries out delay and focusing processing to the echo data received, obtains 1 width raw ultrasound echo；Institute
There is transducer array element successively to emit ultrasonic wave, obtains the raw ultrasound echo of width number identical as array number.
Further, the expression formula of the raw ultrasound echo is,
Wherein, xnm(k) to emit ultrasonic wave by n-th of array element when, the echo data that m-th of array element receives,
The delay time of each pixel when for the transmitting of n-th array element, m-th of array element receives echo-signal, ω is unit matrix；M=1,
2 ..., M, M are total number for receiving array element, and n=1,2 ..., N, N is the number of total transmitting array element, M=N；
The calculation formula of the delay time of each pixel are as follows:
Wherein,Respectively emit array element, pixel and the position coordinates vector for receiving array element, c
Bulk sound velocity when propagating in tissue for ultrasonic wave, fs then represent the sample rate of system.
Further, smoothed out echo matrix is the expression formula of X (k) are as follows:
Wherein, L is the dimension of the smooth submatrix of setting, L≤N/2.
Further, in step 3, the covariance matrix R of the echo-signal is obtained by calculating sample covariance matrix
(k)。
Further, the calculation formula of the white noise signal are as follows:
White noise signal ε is added in the covariance matrix R (k) of the echo-signal, obtains addition white noise signal
Covariance matrixExpression formula are as follows:
Wherein, I is unit diagonal matrix.
Further, the final ultrasonic echo image expression formula are as follows:
Im=sum (λk max*X(k))
Wherein, λk maxFor the maximum eigenvalue of k-th of pixel, X (k) is smoothed out echo data matrix, λk maxWith
X (k) is calculated as unit of pixel.
On the other hand, a kind of ultrasound image contrast and lateral resolution optimization system are provided, comprising:
Original image securing component, for obtaining N width raw ultrasound echo；
Picture smooth treatment component, the N width raw ultrasound echo for obtaining to original image securing component is with picture
Vegetarian refreshments is smoothed for unit, obtains echo data matrix, and by echo data Transfer-matrix to data handling component；
Echo-signal is calculated for receiving and processing the echo data matrix after smoothing processing in data handling component
Covariance matrix；It is also used to add white noise in the covariance matrix of echo-signal, calculates the association for obtaining addition white noise
The characteristic value and feature vector of variance matrix；
Image generation component, using the maximum eigenvalue for the covariance matrix for adding white noise signal to smoothed out echo
Data matrix is constrained, and final ultrasonic echo image is obtained.
Further, ultrasonic echo image formation component implementation procedure is as follows:
Smoothed out echo data matrix is constrained based on the mathematical feature of echo-signal, the number of the echo-signal
Learn feature are as follows:
The feature vector of the covariance matrix of echo-signal is mutually perpendicular to；
The characteristic value of covariance matrix presses descending order, and the corresponding feature vector of characteristic value successively represents expectation letter
Number, the direction of arrival of interference signal and noise signal；
Maximum eigenvalue is proportional to desired signal and the ratio between interference and noise signal.
Further, described image formation component exports final surpass based on following final ultrasonic echo image expression formulas
Sound echo:
Im=sum (λk max*X(k))
Wherein, λk maxFor the maximum eigenvalue of k-th of pixel, X (k) is smoothed out echo data matrix, λk maxWith
X (k) is calculated as unit of pixel.
Compared with prior art, the present invention one of at least has the advantages that:
A) ultrasound image contrast provided by the invention and lateral resolution optimization method, are connect using ultrasound transducer array
The echo-signal received have coherence feature, desired signal belong to coherent signal, interference and noise signal belong to it is incoherent
Signal constrains collected echo-signal using the characteristic value of the covariance matrix of addition white noise signal, and desired signal is big
The maximum eigenvalue of pixel is bigger, calculates maximum eigenvalue by each pixel to ultrasound image, and then in the enhancing phase
Interference and noise signal are inhibited while hoping signal, therefore improves ultrasound image signal-to-noise ratio, significantly improve ultrasonic system
Contrast and lateral resolution.
B) ultrasound image contrast provided by the invention and lateral resolution optimization method, step is simple, is skillfully constructed, number
It is small according to operand, more preferably system imaging quality is obtained, this method has highly important research significance and economic value, application
Prospect is extensive.
C) ultrasound image contrast and lateral resolution optimization system provided by the invention, original image securing component utilize
The ultrasound echo signal that synthetic aperture technique is emitted and receives while focusing, picture smooth treatment component are original super to N
Sound echo is smoothed, data handling component calculate obtain addition white noise covariance matrix characteristic value and
Feature vector；Mathematical feature of the image generation component based on ultrasound echo signal, the covariance matrix constructed using echo-signal
Maximum eigenvalue replace coherence factor to be calculated, constrain collected echo-signal, enhance relevant desired signal, inhibit
Interference and noise signal, and then can significantly improve the contrast and lateral resolution of ultrasonic echo image.Since optimization is
It unites identical as the principle of optimization method, optimization system also has the corresponding technical effect of above-mentioned optimization method.
It in the present invention, can also be combined with each other between above-mentioned each technical solution, to realize more preferred assembled schemes.This
Other feature and advantage of invention will illustrate in the following description, also, certain advantages can become from specification it is aobvious and
It is clear to, or understand through the implementation of the invention.The objectives and other advantages of the invention can by specification, claims with
And it is achieved and obtained in specifically noted content in attached drawing.
Detailed description of the invention
Attached drawing is only used for showing the purpose of specific embodiment, and is not to be construed as limiting the invention, in entire attached drawing
In, identical reference symbol indicates identical component.
Fig. 1 is ultrasound image contrast and lateral resolution optimization method flow chart of steps in embodiment；
Fig. 2 is the ultrasonic echo image that ultrasound image contrast and lateral resolution optimization method obtain in embodiment and its
The ultrasonic echo image comparative result figure that his existing method obtains.
Specific embodiment
Specifically describing the preferred embodiment of the present invention with reference to the accompanying drawing, wherein attached drawing constitutes the application a part, and
Together with embodiments of the present invention for illustrating the principle of the present invention, it is not intended to limit the scope of the present invention.
A specific embodiment of the invention discloses a kind of ultrasound image contrast and lateral resolution optimization method,
Fig. 1 shows the step flow chart of ultrasound image contrast and lateral resolution optimization method in the present embodiment, the optimization method
Include the following steps:
Step 1: emitting ultrasonic wave using the single array element of ultrasound transducer array, and receive ultrasound using all array elements and return
Wave carries out delay and focusing processing to the echo data received, obtains 1 width raw ultrasound echo；All transducer array elements
Successively emit ultrasonic wave, obtains the raw ultrasound echo of width number identical as array number.
When n-th of array element transmitting ultrasonic wave, each pixel echo data corresponding to different reception array elements is folded
Add, 1 width raw ultrasound echo LRI of acquisitionn, it is expressed as
Wherein, xnmIt (k) is the echo data that m-th of array element receives when emitting ultrasonic wave by n-th of array element.
The delay time of each pixel when for the transmitting of n-th array element, m-th of array element receives echo-signal, m=1,2 ..., M, M is always to connect
The number of array element is received, ω is unit matrix.
The calculation formula of the delay time of each pixel are as follows:
WhereinRespectively emit array element, pixel and the position coordinates vector for receiving array element, c is
Bulk sound velocity when ultrasonic wave is propagated in tissue, fs then represent the sample rate of system.
Control ultrasonic transducer array element successively emit ultrasonic wave, all array elements receive ultrasonic wave, can successively obtain N it is original
Ultrasonic echo image LRIn, wherein n=1,2 ..., N, N are the number of total transmitting array element, obtain N width raw ultrasound echo altogether
Image.In order to improve the image quality of system, the as far as possible transmitting of raising system and receiving aperture, therefore, it is necessary to each array element is equal
Transmitting, all array elements receive, therefore the number of total transmitting array element is equal with total number of array element that receives, and is equal to ultrasonic transducer
Total array number of array, i.e. N=M.
Step 2: the N width raw ultrasound echo obtained to step 1 is smoothed as unit of pixel, is obtained
Echo data matrix.
All raw ultrasound echoes are smoothed as unit of pixel, construct echo data matrix.By
Belong to broadband signal in ultrasound echo signal, the stability of building echo matrix can be improved in smoothing processing.Building it is smooth after
Echo matrix be X (k) expression formula are as follows:
Wherein, L is the dimension of the smooth submatrix of setting, L≤N/2
Step 3: based on the echo data matrix X (k) after smoothing processing, calculating the covariance matrix of echo-signal.
In practical applications, therefore the covariance matrix for being often difficult to obtain accurate interference plus noise is assisted using sample
Variance matrix substitutes the covariance matrix of interference plus noise, i.e., obtains the echo-signal by calculating sample covariance matrix
Covariance matrix.
The covariance matrix R (k) of obtained echo-signal are as follows:
Wherein, when K is that time smoothing is handled, the front and back more pixel quantity that takes.
Step 4: white noise signal is added in the covariance matrix of echo-signal, the association after calculating addition white noise signal
The characteristic value and feature vector of variance matrix.
In order to improve the stability of covariance matrix, avoiding the covariance matrix of building is singular matrix, introduces diagonal add
Carry algorithm.The core of diagonal loading algorithm is addition white noise signal ε on the basis of covariance matrix, the white noise letter of addition
Number energy be much smaller than the energy of pixel itself, therefore do not influence the maximum eigenvalue of covariance matrix, white noise signal
Calculation formula is as follows:
White noise signal ε is added in the covariance matrix R (k) for the echo-signal that step 3 constructs, obtains addition white noise
The covariance matrix of acoustical signalCalculate the characteristic value and feature vector of the covariance matrix of addition white noise.Wherein,
Add the covariance matrix of white noise signalExpression formula are as follows:
Wherein,For the covariance matrix for adding white noise signal, I is unit diagonal matrix.
Step 5: utilizing the covariance matrix of addition white noise signalMaximum eigenvalue λk maxTo smoothed out time
Wave data matrix X (k) is constrained, and final ultrasonic echo image is obtained.
Due to final sample covariance matrix(covariance matrix for having added white noise signal) is
Hermitian matrix, Hermitian matrix have the feature that
(1) all characteristic values of Hermitian matrix are all real numbers；
(2) feature vector corresponding to the different characteristic value of Hermitian matrix is mutually orthogonal；
(3) if matrix AN×NIt is Hermitian matrix, then matrix AN×NA can be resolved intoN×N=E ∧ EHForm.
The decomposition is referred to as spectral theorem, wherein ∧=diag [λk1,λk2,…,λkN] it is matrix AN×NAll eigenvalue clusters to angular moment
Battle array, E=[ek1,ek2,…,ekN] it is then N × N-dimensional matrix that the feature vector corresponding to characteristic value is constituted, wherein k, which is represented, to be appointed
Meaning pixel.
For ultrasonic echo data, final sample covariance matrixIt is L × L dimension matrix, corresponding L square in descending order
The characteristic value of formula arrangement, λk1≥λk2≥…≥λkL.The desired signal S (k) and maximum eigenvalue λ of ultrasound echo signalk1It is corresponding
Feature vector ek1In the same direction, feature vector ek1That is the direction of arrival of desired signal.The corresponding feature vector e of other characteristic valueskp,p
≠ 1 represents the incoming direction of interference signal I (k) and noise signal N (k), the bigger feature vector e of characteristic valuekp, the representative of p ≠ 1
The incoming direction of the bigger interference signal of energy.
Mathematical feature based on echo-signal: the feature vector of the covariance matrix of echo-signal is mutually perpendicular to；Covariance
The characteristic value of matrix press descending order, the corresponding feature vector of characteristic value successively represent desired signal, interference signal and
The direction of arrival of noise signal；Maximum eigenvalue is proportional to desired signal and the ratio between interference and noise signal.For emitting and connecing
The defocused ultrasound echo signal of pinching, desired signal are coherent signal, and interference and noise signal are incoherent signal, therefore maximum special
Value indicative can characterize the degree of coherence of echo-signal.Utilize the maximum eigenvalue λ of echo data covariance matrixk maxConstrain step 2
The echo data matrix X (k) of building can enhance the desired signal in echo, inhibit interference and noise signal, Jin Erti
The signal-to-noise ratio of high system improves picture contrast and lateral resolution, improves echo quality.
Preferably, step 5 is based on the covariance matrix for having added white noise signalCalculate maximum eigenvalue λk max,
λk max=λk1.Utilize the maximum eigenvalue λ of acquisitionk maxThe smoothed out echo data matrix X (k) that step 2 constructs is constrained, i.e.,
Final ultrasonic echo image can be obtained:
Im=sum (λk max*X(k))
Wherein, λk maxFor the maximum eigenvalue of k-th of pixel, X (k) is smoothed out echo data matrix, maximum special
Value indicative λk maxIt is calculated as unit of pixel with smoothed out echo data matrix X (k).Therefore, for entire ultrasonic echo
Image, the maximum eigenvalue λ of each pixelk maxDifferent, the ultrasound finally obtained with smoothed out echo data matrix X (k)
Echo has more preferably contrast and lateral resolution.
Compared with prior art, ultrasound image contrast provided in this embodiment and lateral resolution optimization method are a kind of
New coherence factor algorithm, the ultrasound echo signal for being emitted using synthetic aperture technique and receiving while focusing, based on super
The final sample covariance matrix of the mathematical feature of sound echo-signal, echo data (has added the covariance of white noise signal
Matrix) maximum eigenvalue be proportional to desired signal and the ratio between interference signal and noise signal, and desired signal belong to it is relevant
Signal, interference and noise signal belong to incoherent signal, are constrained using the characteristic value of the covariance matrix of addition white noise signal
Collected echo-signal, namely to be calculated be concerned with is replaced using the maximum eigenvalue of the covariance matrix of echo-signal building
Coefficient constrains collected echo-signal, enhances relevant desired signal, inhibits interference and noise signal, and then can be obvious
Raising ultrasonic echo image contrast and lateral resolution.
As shown in Fig. 2, using ultrasound image contrast provided in this embodiment and lateral resolution optimization method and other
The comparative result figure of method: where Fig. 2 (a) is the ultrasonic echo image that delay and focusing handles that DS is obtained, and delay and focusing handles DS
Realize collectiong focusing；Fig. 2 (b) is the ultrasonic echo image that synthetic aperture technique SA is obtained, and synthetic aperture technique SA is realized
Transmitting and collectiong focusing, i.e., the ultrasound echo signal X (k) of unused maximum eigenvalue constraint；Fig. 2 (c) is amplitude Apodization techniques
(Hamming window), the ultrasonic echo image that SA (Hamming) is obtained, i.e. traditional the utilizing of SA (hamming) fix window function about
Ultrasonic echo image after beam ultrasound echo signal X (k)；Fig. 2 (d) is that the optimization method (CFSA technology) of the present embodiment obtains
Ultrasonic echo image；Image's dynamic display range is 60dB.The results show that obtaining ultrasound by optimization method provided in this embodiment
The contrast and lateral resolution of echo are significantly better than that the ultrasonic echo image that other methods obtain.
Embodiment two
The present embodiment provides a kind of ultrasound image contrast and lateral resolution optimization systems, comprising:
Original image securing component, for obtaining N width raw ultrasound echo；
Picture smooth treatment component, the N width raw ultrasound echo for obtaining to original image securing component is with picture
Vegetarian refreshments is smoothed for unit, obtains echo data matrix, and by echo data Transfer-matrix to data handling component；
Echo-signal is calculated for receiving and processing the echo data matrix after smoothing processing in data handling component
Covariance matrix；It is also used to add white noise in the covariance matrix of echo-signal, calculates the association for obtaining addition white noise
The characteristic value and feature vector of variance matrix；
Image generation component, using the maximum eigenvalue for the covariance matrix for adding white noise signal to smoothed out echo
Data matrix is constrained, and final ultrasonic echo image is obtained.
In the present embodiment, ultrasonic echo image formation component implementation procedure is as follows:
Smoothed out echo data matrix is constrained based on the mathematical feature of echo-signal, the number of the echo-signal
Learn feature are as follows:
The feature vector of the covariance matrix of echo-signal is mutually perpendicular to；
The characteristic value of covariance matrix presses descending order, and the corresponding feature vector of characteristic value successively represents expectation letter
Number, the direction of arrival of interference signal and noise signal；
Maximum eigenvalue is proportional to desired signal and the ratio between interference and noise signal.
In the present embodiment, image generation component exports final ultrasound based on following final ultrasonic echo image expression formulas
Echo:
Im=sum (λk max*X(k))
Wherein, λk maxFor the maximum eigenvalue of k-th of pixel, X (k) is smoothed out echo data matrix, maximum special
Value indicative λk maxIt is calculated as unit of pixel with smoothed out echo data matrix X (k).Therefore, for entire ultrasonic echo
Image, the maximum eigenvalue λ of each pixelk maxDifferent, the ultrasound finally obtained with smoothed out echo data matrix X (k)
Echo has more preferably contrast and lateral resolution.
The ultrasound image contrast and lateral resolution optimization system that the present embodiment supplies, original image securing component utilize conjunction
The ultrasound echo signal for being emitted at aperture technique and receiving while focusing, picture smooth treatment component is to N width raw ultrasound
Echo is smoothed, and obtains echo data matrix, and data handling component receives and processes the echo after smoothing processing
Data matrix calculates the characteristic value and feature vector for obtaining the covariance matrix of addition white noise；Image generation component is based on
The mathematical feature of ultrasound echo signal replaces phase to be calculated using the maximum eigenvalue of the covariance matrix of echo-signal building
Responsibility number constrains collected echo-signal, enhances relevant desired signal, inhibits interference and noise signal, and then can be bright
The contrast and lateral resolution of aobvious raising ultrasonic echo image.Since system provided in this embodiment and embodiment one provide
Embodiment of the method principle it is identical, so this system also has the corresponding technical effect of above method embodiment one.
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto,
In the technical scope disclosed by the present invention, any changes or substitutions that can be easily thought of by anyone skilled in the art,
It should be covered by the protection scope of the present invention.
Claims (10)
1. a kind of ultrasound image contrast and lateral resolution optimization method, which comprises the following steps:
Step 1: obtaining N width raw ultrasound echo using ultrasonic transducer；
Step 2: the N width raw ultrasound echo being smoothed as unit of pixel, obtains echo data square
Battle array；
Step 3: based on the echo data matrix after smoothing processing, calculating the covariance matrix of echo-signal；
Step 4: adding white noise signal in the covariance matrix of echo-signal, calculate the covariance square of addition white noise signal
The characteristic value and feature vector of battle array；
Step 5: using addition white noise signal covariance matrix maximum eigenvalue to smoothed out echo data matrix into
Row constraint, obtains final ultrasonic echo image.
2. ultrasound image contrast according to claim 1 and lateral resolution optimization method, which is characterized in that step 1
In, emit ultrasonic wave using the single array element of ultrasound transducer array, and receive ultrasonic echo using all array elements, to receiving
Echo data carry out delay and focusing processing, obtain 1 width raw ultrasound echo；All transducer array elements successively emit ultrasound
Wave obtains the raw ultrasound echo of width number identical as array number.
3. ultrasound image contrast according to claim 1 and lateral resolution optimization method, which is characterized in that the original
The beginning expression formula of ultrasonic echo image is,
Wherein, xnm(k) to emit ultrasonic wave by n-th of array element when, the echo data that m-th of array element receives,It is
The delay time of each pixel when n array element transmitting, m-th of array element receives echo-signal, ω are unit matrix；M=1,2 ...,
M, M are total number for receiving array element, and n=1,2 ..., N, N is the number of total transmitting array element, M=N；
The calculation formula of the delay time of each pixel are as follows:
Wherein,Respectively emit array element, pixel and the position coordinates vector for receiving array element, c is super
Bulk sound velocity when sound wave is propagated in tissue, fs then represent the sample rate of system.
4. ultrasound image contrast according to claim 1 and lateral resolution optimization method, which is characterized in that after smooth
Echo matrix be X (k) expression formula are as follows:
Wherein, L is the dimension of the smooth submatrix of setting, L≤N/2.
5. ultrasound image contrast according to claim 1 and lateral resolution optimization method, which is characterized in that step 3
In, the covariance matrix R (k) of the echo-signal is obtained by calculating sample covariance matrix.
6. ultrasound image contrast according to claim 5 and lateral resolution optimization method, which is characterized in that described white
The calculation formula of noise signal are as follows:
White noise signal ε is added in the covariance matrix R (k) of the echo-signal, obtains the association of addition white noise signal
Variance matrixExpression formula are as follows:
Wherein, I is unit diagonal matrix.
7. ultrasound image contrast according to claim 6 and lateral resolution optimization method, which is characterized in that it is described most
Whole ultrasonic echo image expression formula are as follows:
Im=sum (λkmax*X(k))
Wherein, λkmaxFor the maximum eigenvalue of k-th of pixel, X (k) is smoothed out echo data matrix, λkmaxIt is equal with X (k)
It is calculated as unit of pixel.
8. a kind of ultrasound image contrast and lateral resolution optimization system characterized by comprising
Original image securing component, for obtaining N width raw ultrasound echo；
Picture smooth treatment component, the N width raw ultrasound echo for obtaining to original image securing component is with pixel
It is smoothed for unit, obtains echo data matrix, and by echo data Transfer-matrix to data handling component；
The association of echo-signal is calculated for receiving and processing the echo data matrix after smoothing processing in data handling component
Variance matrix；It is also used to add white noise in the covariance matrix of echo-signal, calculates the covariance for obtaining addition white noise
The characteristic value and feature vector of matrix；
Image generation component, using the maximum eigenvalue for the covariance matrix for adding white noise signal to smoothed out echo data
Matrix is constrained, and final ultrasonic echo image is obtained.
9. ultrasound image contrast according to claim 8 and lateral resolution optimization system, which is characterized in that ultrasound is returned
Wave image generation component implementation procedure is as follows:
Smoothed out echo data matrix is constrained based on the mathematical feature of echo-signal, the mathematics of the echo-signal is special
Sign are as follows:
The feature vector of the covariance matrix of echo-signal is mutually perpendicular to；
The characteristic value of covariance matrix presses descending order, and the corresponding feature vector of characteristic value successively represents desired signal, does
Disturb the direction of arrival of signal and noise signal；
Maximum eigenvalue is proportional to desired signal and the ratio between interference and noise signal.
10. ultrasound image contrast and lateral resolution optimization system according to claim 8 to 9, which is characterized in that institute
It states image generation component and exports final ultrasonic echo image based on following final ultrasonic echo image expression formulas:
Im=sum (λkmax*X(k))
Wherein, λkmaxFor the maximum eigenvalue of k-th of pixel, X (k) is smoothed out echo data matrix, λkmaxIt is equal with X (k)
It is calculated as unit of pixel.
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