CN104200474B - A kind of method of digital image analysis obtaining deformation of body amount - Google Patents
A kind of method of digital image analysis obtaining deformation of body amount Download PDFInfo
- Publication number
- CN104200474B CN104200474B CN201410448654.0A CN201410448654A CN104200474B CN 104200474 B CN104200474 B CN 104200474B CN 201410448654 A CN201410448654 A CN 201410448654A CN 104200474 B CN104200474 B CN 104200474B
- Authority
- CN
- China
- Prior art keywords
- function
- deformation
- pixel
- obtaining
- displacement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Length Measuring Devices By Optical Means (AREA)
- Image Analysis (AREA)
Abstract
The invention discloses a kind of method of digital image analysis obtaining deformation of body amount, the subject image before step S1 obtains deformation and after deformation, step S2 chooses coordinate identical analyzed area at same object same section in two images respectively；Step S3 carries out fast Fourier transform and Mathematical treatment to the gray value of the pixel in two regions respectively, obtains with regard to the gray value of pixel, deflection and the function with regard to variable in Mathematical treatment in analyzed area；Step S4 is to calculate respectively to become in described Mathematical treatment to measure four different functions obtaining during four different definite values；Step S5 is to carry out Mathematical treatment to four different functions in step S4, thus obtaining the 5th function；Step S6 carries out Fourier transformation to described 5th function, obtains comprising the impulse function of object deflection, calculates to obtain the position of highest pulse point in this impulse function, the coordinate of this position is deformation of body and causes deflection in X-direction and Y direction.
Description
Technical field
The invention belongs to engineering survey field, more particularly, to a kind of digital image analysises obtaining deformation of body amount
Method.
Background technology
Measurement material malformation thus obtain its mechanical property be always vast mechanics worker of concern important
Problem.Generally material is made standard specimen in the mechanical behavior experiment of material, relend and help extensometer to obtain sample deformation, root
The mechanical property of material can be calculated according to material deformation.Early application mechanical lever-type extensometer, is typically now drawn with strain-type
Stretch meter, the sensitive deformation element in Strain Extensometer is the cantilever beam being made up of elastomeric material, the free end of this cantilever beam is
One edge of a knife, during work, it is tightly fastened with measured piece, and beam is stained with the foil gauge of measurement deformation.
Above adopt foil gauge contact measurement method there are the following problems：In some fabrics, the flexible material such as plastics
On cannot adopt extensometer metering system；Under the adverse circumstances such as High Temperature High Pressure, conventional foil gauge cannot adapt to dislike at all
Bad use environment, and high temperature can make component creep occur, even if also can be because being affected by high temperature using high temperature resistance strain gauge
Can accurately measure；The cantilever beam edge of a knife on extensometer can be because using rust, thus leading to contact force to decline and cause for a long time
Test error；For in test rubber this kind of large deformation material or metal fracture fatigue test, the extensometer cantilever beam edge of a knife can be because
Badly damaged for vibrations during Materials Fracture and impact；During for some small test specimens, do not have suitable gauge length extensometer and no
Method records deformation.
Content of the invention
Disadvantages described above for prior art or Improvement requirement, the invention provides a kind of numeral obtaining deformation of body amount
Image analysis method, its object is to obtain the displacement that object is caused due to self-deformation, without contact member, not to component
Damage, using image processing techniquess object analysis deformation, can quick obtaining result, thus solve to need to connect in current method
Tactile body surface or the technical problem of process step consuming time length.
For achieving the above object, the invention provides a kind of method of digital image analysis obtaining deformation of body amount, it is used for
Obtain the displacement that object is caused due to self-deformation, surface displacement amount is object due to the particle deforming or movement causes
Between relative movement distance it is characterised in that comprising the steps of：
S1：Using two width images before and after same position shoots same deformation of body for the photographing device, and this two width image
At least include at least one same section of this object；
S2：An analyzed area is randomly selected respectively in described two width images in the region of same object same section,
The shape of this two analyzed areas and the pixel quantity all same comprising, and the initial seat of this two regions pixel in the picture
Mark is also identical respectively with the terminal point coordinate of pixel；
S3：Respectively fast Fourier change is carried out to the gray value of the described pixel in two regions in described step S2
Change, respectively obtain the first transformation results before representing deformation of body and represent the second transformation results after deformation of body, due to thing
The displacement that after body deformation, image causes with respect to image modification deformation before deformation, so the second transformation results are exactly the first change
Change the function of result and displacement；Second transformation results are multiplied by angle variables, obtain the 3rd transformation results further, will
Described first transformation results are added with described 3rd transformation results, and to obtain scaling results, described scaling results are matrix, to this
Matrix carries out conjugate multiplication process, obtains making with regard to the gray value of pixel, deformation in the described analyzed area of image before deformation
The displacement becoming and the function of described angle variables；
S4：Calculating described angle variables respectively takes the first function obtaining during the first definite value, angle variables to take the second definite value
When the second function that obtains, angle variables take the 3rd function obtaining during three definite values and angle variables to obtain when taking four definite values
The 4th function arriving；
S5：To the first function in described step S4, second function, the 3rd function and the 4th function are carried out at mathematics
Reason, to balance out the gray value of image before a deformation of body coefficient in a frequency domain caused by conjugate multiplication, thus obtain the
Five functions；
S6：Fourier transformation is carried out to described 5th function, obtains the impulse function comprising to deform the displacement causing, meter
Calculate the position obtaining highest pulse point in this impulse function, the coordinate of this position is the displacement that deformation of body causes.
Further, in described step S4 the first definite value, the second definite value, the 3rd definite value and the 4th definite value be respectively 0, π/
2nd, π and 3 pi/2s.
Further, the 5th function I obtaining in described step S55As follows：
Wherein, I1、I2、I3And I4It is respectively first function, second function, the 3rd function and the 4th function, u, v divide
It is not the coordinate unit after its Fourier transformation, M, N are the x of the described analyzed area chosen respectively, the pixel quantity in y direction,
Dx and dy respectively deforms the displacement causing, and π is angle in mathematics, equal to 180 °.
Further, in described step S6, described impulse function and its conversion process are：
In formula, M, N are the x of the described analyzed area chosen respectively, the pixel quantity in y direction, x and y is respectively by image
Coordinate unit in the spatio-temporal region of gray value composition of in-plane displancement and pixel, dx and dy deforms the x causing, y side respectively
To surface displacement amount, u, v are the coordinate unit after Fourier transformation respectively, j be imaginary unit, δ (x) be Dirac function, e
The truth of a matter for natural logrithm.
The inventive method thinks that object causes surface displacement due to deformation, and this surface displacement amount is only due to object becomes
Shape causes, and therefore this displacement is less.Same position shoot deformation of body front and rear surfaces image, this surface image because
Deformation of body and there occurs change, its corresponding pixel also there occurs movement, identical according to gray value, solve have identical
The displacement that the pixel of gray value occurs, the surface displacement as being caused due to deformation of body.
In general, by the contemplated above technical scheme of the present invention compared with prior art, can obtain down and show
Beneficial effect：
1st, the method for present invention collection initial data shoots the photo before and after deformable object, and mode is simple, and to various
Test environment all can shoot, not tested person environmental effect, applied widely, and shoots photo without contact member, have and do not break
The advantage of bad component.
2nd, the inventive method is based on image processing techniquess object analysis and deforms, using common Fourier transformation in mathematics or
Person's speed change Fourier transformation is processed it is not necessary to be carried out search process, can directly obtain the displacement that deformation of body causes,
Can quick obtaining result, time-consuming.
Brief description
Fig. 1 (a) and Fig. 1 (b) is that in the embodiment of the present invention, surface is sprayed with before speckle object same section deforms and becomes respectively
Picture after shape；
Fig. 2 is the bar graph of the 5th function being obtained using method in the embodiment of the present invention；
Fig. 3 is the spectrogram of the impulse function in step S6 being obtained using present invention method.
Specific embodiment
In order that the objects, technical solutions and advantages of the present invention become more apparent, below in conjunction with drawings and Examples, right
The present invention is further elaborated.It should be appreciated that specific embodiment described herein is only in order to explain the present invention, and
It is not used in the restriction present invention.As long as additionally, involved technical characteristic in each embodiment of invention described below
The conflict of not constituting each other just can be mutually combined.
Embodiment comprises the steps of：
S1：Shoot surface using camera in same position and there is image before and after the deformation of body of speckle, as shown in figure 1,
Fig. 1 (a) is the photo of speckle part before deformation, and Fig. 1 (b) is the photo of speckle part after deformation, and this two width image includes this phase
Same part, i.e. speckle part.
S2：Analyzed area is randomly selected respectively in two images in region near speckle, this two analyzed areas
Shape is identical, is square, and the pixel quantity that two regions comprise is also identical, in the present embodiment, before being deformed and deformation
Afterwards image in choose pixel origin coordinates be (350,150), end pixel point coordinates is (450,250), point
Analysis region is size 101 × 101.
S3：Respectively fast Fourier transform is carried out to the gray value of the pixel in two regions, respectively obtain expression thing
The first transformation results before body deformation and the second transformation results after expression deformation of body, the first transformation results are exponential function
F0(u, v), the second transformation results are exponential function F1(u, v), two exponential functions are as follows respectively：
In formula, M, N are the x of the analyzed area chosen respectively, the pixel quantity in y direction, x and y is respectively by the plane of delineation
Displacement and pixel gray value composition spatio-temporal region in coordinate, dx and dy be respectively due to deformation cause pixel its
The displacement in x, y direction, u, v are the coordinate unit after Fourier transformation respectively, and j is imaginary unit, and e is the truth of a matter of natural logrithm, π
For angle in mathematics, equal to 180 °, f0(x, y) represent deformation before between image intensity value and coordinate relation function, f0(x+dx,y+
Dy the relation function between the gray value of image and coordinate after) then expression deforms.Due to it is believed that it is that translation is closed that deformation moves forward and backward
System, so, before and after deformation there is the shift value of X-direction and Y-direction in the gray value of image pixel, i.e. respectively dx and dy, namely
The surface displacement amount producing before and after deformation of body.
By the fast Fourier transform result of gradation of image value function after deformation, namely the second transformation results F1(u, v) takes advantage of
Upper angle variablesObtain the 3rd transformation results F3(u, v), is shown below：
In formula, M, N are the x of the described analyzed area chosen respectively, the pixel quantity in y direction, x and y is respectively due to figure
Coordinate in the spatio-temporal region of gray value composition of image plane displacement and pixel, dx and dy is the displacement in y direction in x respectively,
U, v are the coordinate unit after Fourier transformation respectively, and j is imaginary unit,For needing increased offset variable.
It is the result that a relative motion causes due to deforming the displacement causing, it depends on the ash of the image before deformation
Why angle value, increaseExactly in order to the position caused will be deformed using the displacement that this increases in the process in later stage
Shifting amount is independent of the gray value of image before deformation, thus the displacement offer causing for solving deformation may.
F3(u, v) is one and F0(u, v), surface displacement amount dx and dy and angle variablesRelevant function, so
Afterwards by fast Fourier transform result F of image before this function and deformation0(u, v) is added, and obtains a function Ai(u, v), should
Function is exactly scaling results, and detailed process is shown below：
In formula, M, N are the x of the described analyzed area chosen respectively, the pixel quantity in y direction, x and y is respectively due to figure
Coordinate in the spatio-temporal region of gray value composition of image plane displacement and pixel, dx and dy is the displacement in y direction in x respectively,
U, v are the coordinate unit after Fourier transformation respectively, and j is imaginary unit,For needing increased offset variable.
The function A of this scaling results will be representedi(u, v) conjugate multiplication, obtains in the analyzed area with regard to image before deformation
The function I of the gray value of pixel, the displacement that deformation causes and angle variablesi(u, v), specifically obtains one and F0(u,
V), in surface displacement amount dx and dy and variableRelevant function, is shown below：
Wherein, B0(u, v)=2F0(u,v)F0 *(u, v), in formula, M, N are the x of the described analyzed area chosen respectively, y side
To pixel quantity, x and y be respectively due to plane of delineation displacement and pixel gray value composition spatio-temporal region in seat
Mark, dx and dy is the displacement in y direction in x respectively, and u, v are the coordinate unit after Fourier transformation respectively, and j is imaginary unit,For needing increased offset variable, * represents the transposition that it is shown function.
S4：Calculate described change respectively to measure the first function that obtains during the first definite value, become to measure and obtain during the second definite value
Second function, change measure the 3rd function obtaining during three definite values and change measures the 4th function obtaining during four definite values, this
In embodiment, the first definite value, the second definite value, the 3rd definite value and the 4th definite value are respectivelyWith 3 pi/2s, obtain
To first function, second function, the 3rd function and the 4th function, correspond to I respectively1、I2、I3And I4, specific as follows：
In formula, in formula, M, N respectively be choose described analyzed area x, the pixel quantity in y direction, x and y be respectively by
Coordinate in the spatio-temporal region of the gray value composition of plane of delineation displacement and pixel, dx and dy is in x respectively, y direction
Displacement, u, v are the coordinate unit after Fourier transformation respectively, and j is imaginary unit, B0(u, v)=2F0(u,v)F0 *(u,v).
S5：Mathematical treatment is carried out to support to the first function in step S4, second function, the 3rd function and the 4th function
Disappear the pixel in described four functions gray value it is possible to obtain the 5th function with regard to surface displacement amount dx and dy,
5th function is following trigonometric function：
Wherein, I1、I2、I3And I4It is respectively first function, second function, the 3rd function and the 4th function, u, v divide
It is not the coordinate unit after its Fourier transformation, M, N are the x of the described analyzed area chosen respectively, the pixel quantity in y direction,
Dx and dy respectively deforms the displacement causing, and π is angle in mathematics, equal to 180 °.
With software matlab to trigonometric function I5(u, v) draws, and obtains the bar graph with regard to surface displacement amount dx and dy, such as
Shown in Fig. 2.
S6：Finally, then to I5(u, v) carries out Fourier transformation, can obtain impulse function W (x, y) removing zero-frequency component,
The position of the corresponding point of its highest pulse is exactly required surface displacement amount dx and dy, specific as follows shown：
In formula, M, N are the x of the described analyzed area chosen respectively, the pixel quantity in y direction, x and y is respectively by image
Coordinate unit in the spatio-temporal region of gray value composition of in-plane displancement and pixel, dx and dy deforms the x causing, y side respectively
To surface displacement amount, u, v are the coordinate unit after Fourier transformation respectively, j be imaginary unit, δ (x) be Dirac function, e
The truth of a matter for natural logrithm.
Using MATLAB or other software coding, calculate peak value corresponding coordinate points position it is simply that required surface
The concrete numerical value of displacement dx and dy.It is that dx and dy is respectively 9 pixels in the present embodiment, and 7 pixels, painted using software
Make this impulse function, as shown in Figure 3.
As it will be easily appreciated by one skilled in the art that the foregoing is only presently preferred embodiments of the present invention, not in order to
Limit the present invention, all any modification, equivalent and improvement made within the spirit and principles in the present invention etc., all should comprise
Within protection scope of the present invention.
Claims (3)
1. a kind of method of digital image analysis obtaining deformation of body amount, for obtaining the displacement that object is caused due to self-deformation
Amount, surface displacement amount is object due to the relative movement distance between deformation or the mobile surface particle causing, and its feature exists
In comprising the steps of：
S1：Using two width images before and after same position shoots same deformation of body for the photographing device；
S2：An analyzed area is randomly selected respectively in described two width images, this two in the region of same object same section
The shape of individual analyzed area and the pixel quantity all same comprising, and this two regions in the picture the origin coordinates of pixel and
The terminal point coordinate of pixel is also identical respectively；
S3：Respectively fast Fourier transform is carried out to the gray value of the described pixel in two regions in described step S2, point
The first transformation results before not obtaining representing deformation of body and the second transformation results after expression deformation of body, described second conversion
Result is the function of the first transformation results and surface displacement amount, and the second transformation results are multiplied by angle variablesIts
In, j is imaginary unit,For needing increased offset variable, thus obtain the 3rd transformation results further, by described first
Transformation results are added with described 3rd transformation results, and to obtain scaling results, described scaling results are matrix, and this matrix is carried out
Conjugate multiplication is processed, obtain with regard to the gray value of pixel in the described analyzed area of image before deformation, surface displacement amount and
The function of described angle variables；
S4：Calculate described angle variables respectively and take the first function obtaining during the first definite value, angle variables to take and obtain during the second definite value
To second function, angle variables take the 3rd function obtaining during three definite values and angle variables take and obtain during four definite values
4th function, described first definite value, the second definite value, the 3rd definite value and the 4th definite value are respectively 0, pi/2, π and 3 pi/2s；
S5：To the first function in described step S4, second function, the 3rd function and the 4th function carry out Mathematical treatment, with
Balance out the gray value coefficient caused by conjugate multiplication in a frequency domain of image before deformation of body, to obtain the 5th function；
S6：Fourier transformation is carried out to described 5th function, obtains the impulse function comprising to deform the displacement causing, calculating obtains
Obtain the position of highest pulse point in this impulse function, the coordinate of this position is the displacement that deformation of body causes.
2. as claimed in claim 1 a kind of method of digital image analysis obtaining deformation of body amount it is characterised in that described step
The 5th function I obtaining in rapid S55As follows：
Wherein, I1、I2、I3And I4It is respectively first function, second function, the 3rd function and the 4th function, u, v are it respectively
Coordinate unit after Fourier transformation, M, N are the x of the described analyzed area chosen respectively, the pixel quantity in y direction, dx and dy
Respectively deform the x-axis causing, the displacement in y-axis direction.
3. as claimed in claim 1 or 2 a kind of method of digital image analysis obtaining deformation of body amount it is characterised in that institute
State in step S6, described impulse function and its conversion process are：
In formula, M, N are the x-axis of the described analyzed area chosen respectively, the pixel quantity in y-axis direction, x and y is respectively by image
Coordinate unit in the spatio-temporal region of gray value composition of in-plane displancement and pixel, dx and dy deforms the x-axis causing, y respectively
Axial surface displacement amount, u, v are the coordinate unit after Fourier transformation respectively, and j is imaginary unit, and δ (x) is dirac letter
Number, e is the truth of a matter of natural logrithm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410448654.0A CN104200474B (en) | 2014-09-04 | 2014-09-04 | A kind of method of digital image analysis obtaining deformation of body amount |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410448654.0A CN104200474B (en) | 2014-09-04 | 2014-09-04 | A kind of method of digital image analysis obtaining deformation of body amount |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104200474A CN104200474A (en) | 2014-12-10 |
| CN104200474B true CN104200474B (en) | 2017-03-01 |
Family
ID=52085760
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410448654.0A Active CN104200474B (en) | 2014-09-04 | 2014-09-04 | A kind of method of digital image analysis obtaining deformation of body amount |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104200474B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106247963B (en) * | 2015-06-09 | 2018-11-20 | 中国石油化工股份有限公司 | A kind of detection method of wave detector backup arm deformation |
| CN109087279B (en) * | 2018-06-21 | 2020-11-17 | 华中科技大学 | Method for rapidly acquiring object deformation based on digital image diffraction |
| CN109035201B (en) * | 2018-06-21 | 2021-01-01 | 华中科技大学 | Object deformation obtaining method based on digital image diffraction |
| CN108534702A (en) * | 2018-06-28 | 2018-09-14 | 中国人民武装警察部队学院 | A kind of deflection real-time measurement apparatus and method |
| CN109242905B (en) * | 2018-08-31 | 2021-02-05 | 华中科技大学 | Method for determining object displacement and direction based on digital image diffraction |
| CN116503369B (en) * | 2023-05-06 | 2024-01-26 | 北京思莫特科技有限公司 | Deformation monitoring method of structure and image exposure parameter adjusting method |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102054272B (en) * | 2010-11-03 | 2012-06-27 | 浙江大学 | Displacement vector detection method based on joint fractional Fourier transform and device |
| CN102628676B (en) * | 2012-01-19 | 2014-05-07 | 东南大学 | Adaptive window Fourier phase extraction method in optical three-dimensional measurement |
| CN103697829B (en) * | 2013-12-31 | 2016-08-17 | 合肥工业大学 | The Fast measurement system of in-plane deformation based on spatial phase shift and measuring method |
| CN103793924A (en) * | 2014-01-28 | 2014-05-14 | 河海大学 | Flow field image self-adaption motion vector estimating method based on FHT-CC |
-
2014
- 2014-09-04 CN CN201410448654.0A patent/CN104200474B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN104200474A (en) | 2014-12-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104200474B (en) | A kind of method of digital image analysis obtaining deformation of body amount | |
| JP6240206B2 (en) | Displacement field and strain field measurement method and material testing machine | |
| US10101153B2 (en) | Method and device for detecting deviations of an object surface | |
| PI et al. | Measure strain distribution using digital image correlation (DIC) for tensile tests | |
| CN105091772A (en) | Plane object two-dimension deflection measuring method | |
| CN109242905B (en) | Method for determining object displacement and direction based on digital image diffraction | |
| Chen et al. | New measurement method of Poisson's ratio of PVA hydrogels using an optical flow analysis for a digital imaging system | |
| CN110836825A (en) | Method for estimating tensile deformation of rubber-like superelasticity material in situ based on spherical indentation method | |
| JP2020201146A (en) | Parameter estimating device, parameter estimating method, and program | |
| CN107655756A (en) | A kind of word bomb Modulus Test Method based on speckle printing | |
| US20230099872A1 (en) | Image correlation for end-to-end displacement and strain measurement | |
| Min et al. | Strain measurement during tensile testing using deep learning-based digital image correlation | |
| Mazza et al. | Light optical deformation measurements in microbars with nanometer resolution | |
| Hedayati et al. | Strain measurement and determining coefficient of plastic anisotropy using digital image correlation (DIC) | |
| Jiang et al. | Extracting material parameters of silicone elastomers under biaxial tensile tests using virtual fields method and investigating the effect of missing deformation data close to specimen edges on parameter identification | |
| Bolzon | Advances in experimental mechanics by the synergetic combination of full-field measurement techniques and computational tools | |
| Kleinendorst et al. | Mechanical Shape Correlation: A novel integrated digital image correlation approach | |
| Kang et al. | New measurement method of Poisson’s ratio of thin films by applying digital image correlation technique | |
| CN117030448A (en) | Method and related device for analyzing mechanical test data based on digital image method | |
| JP6464815B2 (en) | Distortion measuring method and apparatus, program and recording medium | |
| HajiRassouliha et al. | Subpixel measurement of living skin deformation using intrinsic features | |
| CN110033435B (en) | High-sensitivity digital image displacement frequency domain analysis method | |
| CN114266776B (en) | Digital image correlation method applying composite crack displacement field function | |
| CN109035201A (en) | A kind of object deflection acquisition methods based on digital picture diffraction | |
| CN103218774B (en) | Based on the grid geometric phase analytic approach artificial processed of local high resolution Fourier transform |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |