CN105931250B - A kind of equivalent grain size conversion method of aspherical bubble - Google Patents
A kind of equivalent grain size conversion method of aspherical bubble Download PDFInfo
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Abstract
The invention discloses a kind of equivalent grain size conversion methods of aspherical bubble, center-of-mass coordinate is calculated for each bubble profile, using the mass center as coordinate origin, establish plane right-angle coordinate, number of pixels corresponding to radius of the bubble profile in X-axis and Y direction is calculated separately out, and is denoted as r respectivelyx、ry；R is selected respectivelyxAnd ryAs number of pixels r corresponding to the radius on the bubble profile in a space rectangular coordinate system Z-directionz, two ellipsoid volumes are calculated according to ellipsoid calculation formula, and seek volume of the average value of two ellipsoid volumes as the aspherical bubble；The equivalent grain size of the aspherical bubble is calculated using spherical volume formula.The present invention may be implemented to calculate the three-dimensional equivalent volume of the small aspheres bubble image of two dimension, and can reduce the error during equivalency transform, improve the computational accuracy of volume, and then improve the precision of equivalent sphere bubble diameter.
Description
Technical field
The invention belongs to water body detection technique fields, specifically, being related to a kind of for being dissolved in water body example
The calculation method for the bubble diameter that bubble is proposed.
Background technique
There is eutrophication in China's urban lakes, according to survey data and evaluation index, 37 of China are main
In lake, the ratio of middle auxotype and middle rich feeding type has been over half, wherein eutrophy type accounts for 14.7%, the rich battalion of weight
The type of supporting accounts for 8.8%.Existing research achievement shows suitable temperature, sluggish flow fluidised form, relatively sufficient total phosphorus, total
The nutritive salt such as nitrogen can all cause planktonic algae burst to be proliferated, to produce eutrophication.Air flotation technology be it is existing compared with
Good removes algae water purification technology, and algae removal rate can achieve 95% or more in the suitable situation of condition.Therefore, flotation waste water treatment skill
Art bubble producing method and in terms of all obtained breakthrough progress.But due to measuring technology
Limitation, must compare slowly the progress of various bubble features, so as to cause huge gap is formd between the two.
Existing bubole analysis method is roughly divided into two class method of acoustics and optics.Wherein, photograph/image capture method is optics
Most direct bubble measurement method in analysis method can measure quantitative and non-quantitation water body simultaneously.As long as water body to be measured connects
The observation end of nearly measuring system, no matter bubble concentration height, optical system can transmit, and then form gas in an imaging device
Steep image.When being analyzed using photograph/image capture method the bubble of dissolution in the seawater, it is necessary first to from the figure taken
Bubble image therein is extracted as in, i.e., the bubble in image is identified, extracts the profile of bubble；Then, according to
The bubble profile extracted calculates the parameters such as bubble diameter, to analyze the distribution situation of bubble diameter in seawater.
During calculating bubble diameter, current calculation method is all the bubble profile that will be extracted mostly
Regard the calculating that sphere carries out particle size parameters as.But influenced by extraneous factors such as gravity, seawater tension, from bubble image
The bubble profile that extracts and can not all be completely rule sphere, if by irregular bubble profile simply according to ball
The partial size calculation method of shape bubble calculates its physical parameter, it is clear that will lead to the inaccuracy of partial size calculated result, and then right
The accurate analysis of later period seawater bubble size distribution situation and the Accurate Prediction of seawater eutrophication generate unfavorable shadow
It rings.
Summary of the invention
The purpose of the present invention is to provide a kind of equivalent grain size conversion methods of aspherical bubble, to improve bubble diameter ginseng
The accuracy that number calculates.
In order to solve the above technical problems, the present invention is achieved by the following scheme:
A kind of equivalent grain size conversion method of aspherical bubble, comprising: shoot water body to be measured, obtain bubble image, and mention
Take out bubble profile；For each bubble profile, the center-of-mass coordinate of the bubble profile is calculated, formula is as follows:Wherein, (xc,yc) it is center-of-mass coordinate, NbIt is the sum of profile and border pixel, (xi,yi) it is profile and border
The coordinate of point；Using the mass center as coordinate origin, plane right-angle coordinate is established, calculates separately out the bubble profile in X-axis
With number of pixels corresponding to the radius in Y direction, and it is denoted as r respectivelyx、ry；If rx≠ry, then determine that the bubble is non-
Spherical bubbles select r respectivelyxAnd ryAs corresponding to the radius on the bubble profile in a space rectangular coordinate system Z-direction
Number of pixels rz, according to ellipsoid calculation formulaCalculate two ellipsoid volumes；Seek two spheroids
Volume V of the long-pending average value as the aspherical bubble；Utilize spherical volume formulaIt calculates described aspherical
Number of pixels p'=r corresponding to the equivalent grain size of bubble.
Further, the r is being calculatedx、ryDuring, if rx=ry, then determine the bubble for spherical bubbles, this
When can directly generate number of pixels p'=r corresponding to the partial size of the bubblex。
In order to obtain the physical size of bubble diameter, after obtaining number of pixels p' corresponding to bubble diameter, preferably hold
The Inversion Calculation process of the following bubble diameter of row: the resolving power test target of the striped group with different in width grade is immersed in water body
In, the striped group on the resolving power test target is shot, target stripe pattern is formed；It is calculated according to the target stripe pattern
Number of pixels corresponding to the width of target striped；For the striped group of each width grade, the width of target striped is established
With the corresponding relationship of number of pixels, relational model is formedWherein, i is striped group #, diIt is i-th of striped
The width of target striped in group,Be width be diTarget striped corresponding to number of pixels,Be width be diMesh
Mark scale factor corresponding to striped；Number of pixels and the striped group j where the p' close target striped are found out, utilizes the
Relational model corresponding to j striped groupCalculate the physical size of the bubble diameter
In order to improve the accuracy of bubble diameter physical size calculating, it is provided on the resolving power test target N number of different wide
The striped group of grade is spent, the N is the positive integer greater than 1；The striped group of N number of different in width grade is wide according to its striped
The corresponding number of pixels of degree is arranged successively with sequence from small to large, forms N+1 section；Wherein, the smallest striped of width
Corresponding number of pixelsFirst section is formed with 0Number of pixels corresponding to the maximum striped of width
It is formed between tail region with+∞N-1 intermediate section is formed by two adjacent number of pixels, i.e.,Judge that the p' falls into which of N+1 section section
It is interior；If the p' falls into first sectionIt is interior, then utilize relational model corresponding to the 1st striped groupCalculate the physical size of the bubble diameterIf the p' is fallen between tail regionIt is interior, then utilize relational model corresponding to n-th striped groupCalculate the bubble
The physical size of partial sizeIf the p' is fallen into some intermediate section, the p' and the area are calculated separately
Between two endpoints number of pixelsRelative error, and choose relative error lesser number of pixels institute
Corresponding relational model calculates the physical size of the bubble diameter.
Preferably, the linear fringe of M equal in width is provided in the striped group described in each, the M is greater than 1
Positive integer；The striped group on the shooting resolving power test target, during forming target stripe pattern, comprising:
The linear fringe of M equal in width in one of striped group, is placed in the field range of shooting by the position for adjusting resolving power test target
It is interior, form target stripe pattern corresponding to the striped group；Change the position of the resolving power test target, successively by remaining each striped
The linear fringe of M equal in width in group is placed in the field range of shooting, is finally formed therewith for N number of striped group
One-to-one N number of target stripe pattern.
Preferably, N number of striped group from bottom to top parallel arrangement on the resolving power test target；In each striped
In group, the linear fringe of a plurality of equal in width is preferably designed to vertical line striped, and be in line in parallel.
In order to obtain the higher number of pixels of precision, target striped is calculated according to the target stripe pattern described
During number of pixels corresponding to width, for the linear fringe point of M equal in width in each target stripe pattern
Number of pixels corresponding to its width is not calculated, and to M number of pixels averaged of acquisition, is denoted as the target striped
Width corresponding to number of pixels.
Compared with prior art, the advantages and positive effects of the present invention are: aspherical bubble equivalent grain size of the invention turns
Method is changed by carrying out the calculating of three-dimensional equivalent volume to the small aspheres bubble image of two dimension, so as to reduce equivalency transform mistake
Error in journey, improves the accuracy of volume calculating, and then improves the precision of equivalent sphere bubble diameter calculating, solves
The problem of micro-analysis equivalent bubble diameter, offers precise data for the microscopic measurement and statistical analysis of bubble diameter.In addition,
The present invention generates the physical size of bubble diameter in such a way that image calibration is combined with Inversion Calculation, and precision is high, in real time
Property it is good, the original position to bubble physical parameter, real-time measurement may be implemented, be suitble to wide in fields in scientific research, teaching, seawater monitoring etc.
General application.
After the detailed description of embodiment of the present invention is read in conjunction with the figure, the other features and advantages of the invention will become more
Add clear.
Detailed description of the invention
Fig. 1 is a kind of overall flow of embodiment of aspherical bubble equivalent grain size conversion method proposed by the invention
Figure；
Fig. 2 is a kind of structural schematic diagram of embodiment of bubble acquisition device；
Fig. 3 is the schematic diagram for the plane right-angle coordinate established using the mass center of bubble profile as coordinate origin；
Fig. 4 is the schematic diagram that bubble profile shown in Fig. 3 forms elliposoidal in a space rectangular coordinate system；
Fig. 5 is a kind of overall flow figure of embodiment of bubble diameter Inversion Calculation method；
Fig. 6 is a kind of arrangement schematic diagram of embodiment of striped group on resolving power test target；
Fig. 7 is the structural schematic diagram being placed in resolving power test target in bubble image capture device shown in Fig. 2；
Fig. 8 is a kind of schematic diagram of embodiment of target stripe pattern.
Specific embodiment
A specific embodiment of the invention is described in detail with reference to the accompanying drawing.
The present embodiment calculates the particle size parameters of bubble using photograph/camera shooting bubble optical analysis method, referring to Fig. 1 institute
Show, mainly comprises the steps that
Bubble image in S101, acquisition water body to be measured.
The present embodiment preferably carries out the intake of bubble image, such as Fig. 2 using special bubble detection device to water body to be measured
Shown in bubble detection device, mainly include imaging device 2 and optical system 3.The imaging device 2 and optical system 3 with
Water body 5 to be measured is isolated, and the opposite sides for the water body 5 to be measured that is placed in, and irradiates water body to be measured using the light that optical system 3 issues
5, so that the brightness of water body 5 to be measured is sufficient for the photographing request of imaging device 2.Water body to be measured is shot using imaging device 2, is formed
Bubble image, to be analyzed for the particle size parameters to the bubble dissolved in water body 5 to be measured.
In order to realize being isolated for imaging device 2 and optical system 3 and water body 5 to be measured, for being suitable under laboratory environment
Bubble detection device, transparent sink can be set between imaging device 2 and optical system 3, water body 5 to be measured is injected into
In bright sink, then starts imaging device 2 and optical system 3 shoots water body 5 to be measured, to form bubble image.
For being suitable for the bubble detection device of site environment, imaging device 2 and optical system 3 can be placed in one
In independent sealed compartment, transparent glass 4, injection and gas in order to light are installed in two sealed compartments side relative to each other
Steep the intake of image.
In the present embodiment, the imaging device 2 is preferably designed using industrial camera cooperation telecentric lens.Select work
Industry camera is than selecting the advantage of general camera to be mainly reflected in: (1) aperture time of industrial camera is very short, can capture quickly
The object of movement；(2) imaging sensor of industrial camera is progressive scan, and the imaging sensor of general camera is that interlacing is swept
It retouches, even fourfold interlacing；(3) shooting speed of industrial camera is much higher than general camera；(4) industrial camera exports
It is uncorrected data, spectral region also tends to wider, compares the image processing algorithm for being appropriate for high quality；(5) industrial camera
It can work long hours；(6) industrial camera can work in than relatively rugged environment.
Telecentric lens are a kind of high-end industrial lens, usually have more outstanding image quality, particularly suitable for dimensional measurement
Application.And the operating distance of general industry camera lens photographic subjects object is shorter, imaging is bigger.Using common lens
When carrying out dimensional measurement, can there are problems that 5: 1) since object being measured is not in the same measurement plane, and cause times magnification
The difference of rate；2) lens distortion is big；3) when object distance becomes larger, the amplification factor of object is also changed；4) resolution of camera lens is not
It is high；5) due to the geometrical property of vision light source, and caused by image edge location uncertainty.And telecentric lens can have
Effect solves the above problem existing for common lens, and without the error in judgement of this property, therefore is suitably applied in high-precision and surveys
Measure metering etc..
Therefore, the present embodiment preferably uses industrial camera cooperation telecentric lens to shoot the bubble image in water body to be measured, with
Help to improve the accuracy of bubble diameter calculating.
S102, bubble profile is extracted.
In the present embodiment, it is preferred to use the method for image procossing extracts gas therein from acquired bubble image
Steep profile.
S103, the center-of-mass coordinate for calculating bubble profile.
Pass through centroid calculation formulaCalculate the mass center of each bubble profile.Wherein, (xc,yc)
It is center-of-mass coordinate, NbIt is the sum of profile and border pixel, (xi,yi) be profile and border point coordinate.
S104, bubble coordinate system is established.
In the present embodiment, preferably plane right-angle coordinate is established, as shown in Figure 3 using the mass center as coordinate origin O.
S105, radius of the bubble in X-axis and Y direction is calculated.
In the present embodiment, due to the bubble image obtained using photograph/image capture method, by shown in Fig. 3
The bubble radius that gets of plane right-angle coordinate be pixel corresponding to radius of the bubble in X-axis and Y direction
Number, is denoted as r respectivelyx、ry。
Since in the bubble profile got, some bubble profiles may be the sphere of rule, and some bubble profiles
It then may be aspherical bubble, i.e., irregular bubble.In order to realize accurate calculating, the present embodiment to two kinds of bubble diameter
By rx=ryBubble profile be determined as spherical bubbles, by rx≠ryBubble profile be determined as aspherical bubble.For spherical gas
It steeps, number of pixels p'=r corresponding to partial sizex, the inverting that step S108 carries out bubble diameter parameter can be jumped directly to
It calculates.For aspherical bubble, then need to execute subsequent equivalent grain size switch process.
S106, the volume for calculating bubble.
In the present embodiment, for aspherical bubble, r can be selected respectivelyxAnd ryIt is straight in space as the bubble profile
Number of pixels r corresponding to radius in angular coordinate system in Z-directionz, as shown in figure 4, then according to ellipsoid calculation formula:Calculate two ellipsoid volumes；Wherein, rx、ry、rzRespectively radius institute of the ellipsoid in X, Y, Z axis is right
The number of pixels answered, V are ellipsoid volume.That is,
By rz=rxAnd rz=ryEllipsoid calculation formula is substituted into respectively, calculates two ellipsoid volumes:
Seek the average value of two ellipsoid volumesVolume V as the aspherical bubble.
S107, the equivalent grain size for calculating bubble.
It in the present embodiment, can be using calculated bubble volume V as sphere volume, conversion for aspherical bubble
Radius of sphericity out, in this, as the equivalent grain size of aspherical bubble.That is,
The volume V of aspherical bubble is substituted into spherical volume formula:To calculate the aspherical bubble
Number of pixels r corresponding to equivalent grain size.For the ease of the Inversion Calculation of subsequent bubble diameter, picture corresponding to bubble diameter is enabled
Plain number p'=r.
Two-dimensional aspherical bubble profile by being converted into three-dimensional ellipsoid profile by the present embodiment, by three-dimensional spheroid
Product calculates the equivalent grain size of irregular bubble as spherical volume, it is possible thereby to improve the accurate of bubble equivalent volume calculating
Degree reduces the error during equivalency transform, with the spherical bubbles volume after equivalent come the equivalent grain size for the irregular bubble that converts,
The conversion accuracy that the equivalent grain size of irregular bubble can be improved solves the problems, such as the equivalent bubble diameter of micro-analysis.
S108, the number of pixels p' according to corresponding to bubble diameter, Inversion Calculation go out the actual physical size of bubble diameter.
For the Inversion Calculation of bubble diameter, as shown in connection with fig. 5, specifically includes the following steps:
S501, production resolving power test target.
As shown in connection with fig. 6, one piece of resolving power test target 1 is designed, the striped of multiple and different width grades is etched on resolving power test target 1
Group, such as width is respectively 2 μm, 3 μm, 4 μm, 5 μm, 7 μm, 10 μm, 20 μm, 50 μm, 100 μm of striped group.It is listed in Fig. 6
Striped group d1, the striped group d2 that width is 20 μm, the striped group d3 that width is 50 μm and the width that width is 10 μm are 100 μm
Striped group d4.
As a kind of preferred design of the present embodiment, preferably by multiple striped groups according to width of fringe by small
Gradually big sequence, the direction of edge from bottom to top are successively arranged on resolving power test target 1, as shown in fig. 6, and in each striped group
In, it is preferably provided the striped of a plurality of equal in width, and the striped of a plurality of equal in width is vertically arranged, as vertical striped, and
It is in line in parallel to each other, to facilitate the target stripe pattern needed for obtaining.
S502, resolving power test target 1 is immersed in water body.
The water body can be water body to be measured, be also possible to other liquid with higher clarity.As the present embodiment
A kind of preferred design, due to water body to be measured carry out bubble image capture during, need using special gas
Steep detection device, such as bubble detection device shown in Fig. 2.It, can for the bubble detection device being suitable under laboratory environment
It resolving power test target 1 to be put into transparent sink, and immerses in the water body inside screw clamp, as shown in Figure 7.By resolving power test target 1
On be etched with the one side face imaging device 2 of striped group, in order to form required target stripe pattern.For being applicable on site
The bubble detection device of environment can first put into the bubble detection device in water body to be measured, then by resolving power test target 1
It is immersed in the water body to be measured 5, and between imaging device 2 and optical system 3, and item will be etched on resolving power test target 1
Imaging device 2 described in the one side face of line group, in order to form required target stripe pattern.
In the present embodiment, no matter which kind of bubble detection device is used, between the imaging device 2 and optical system 3
Distance should be short as far as possible, is preferably limited between 10cm-15cm, and the resolving power test target 1 arrives the distance between described imaging device 2
Also it is limited between 10cm-15cm, to improve the inversion accuracy of bubble diameter.
S503, starting imaging device 2, shoot the striped group on the resolving power test target 1, to form target stripe pattern.
In the present embodiment, the position that can adjust industrial camera and telecentric lens first, makes industrial camera be placed in work
Distance.Then, the position for adjusting resolving power test target 1, is located at striped group to be measured in the field range of industrial camera.
In the present embodiment, preferably by adjusting the position of resolving power test target 1, one of them on resolving power test target 1 is allowed first
The linear fringe of a plurality of equal in width in striped group is placed in the field range of industrial camera, forms mesh corresponding to the striped group
Mark stripe pattern.As shown in figure 8, Fig. 8 lists target stripe pattern corresponding to the striped group that width is 20 μm, in the mesh
Mark the vertical line striped in stripe pattern including 4 d=20 μm of width.
Then, change the position of the resolving power test target 1, successively by the straight line of a plurality of equal in width in remaining each striped group
Striped is placed in the field range of industrial camera, for the resolving power test target 1 with N (N is greater than 1 positive integer) a striped group
It says, remaining N-1 striped group is sequentially placed into the field range of industrial camera, it finally can be for N number of striped
Group forms one-to-one N number of target stripe pattern therewith.
When adjusting the position of resolving power test target 1, in order to guarantee to be formed by the imaging amplification factor of N number of target stripe pattern
It is identical, the distance between resolving power test target 1 and the telecentric lens should be kept constant.
S504, according to target stripe pattern, calculate number of pixels corresponding to the width of target striped.
In the present embodiment, using step S503 N number of target stripe pattern obtained is executed, N number of striped is calculated separately
The number of pixels p width d of target striped in group corresponding in target stripe pattern.Due in each target bar graph
It include the target striped of a plurality of equal in width in picture, as shown in figure 8, in order to improve the accuracy that the number of pixels p is calculated,
The present embodiment preferably generates number of pixels p corresponding to the width d of the target striped using the method for taking mean value.
Specifically, it is assumed that include the target striped of M equal in width in some target stripe pattern, be then directed to institute
The M target striped stated calculates separately out number of pixels corresponding to its width, that is, obtains M number of pixels；To the M
Number of pixels averaged is remembered using the average value as number of pixels p corresponding to the width d of the target striped
Record saves.
Remaining N-1 target stripe pattern is all made of the above method and calculates corresponding to the width for generating its target striped
Number of pixels.
S505, corresponding relationship between the width and number of pixels of target striped is established, forms relational model.
In the present embodiment, for the striped group of each width grade, width (the i.e. target of target striped is established respectively
The actual physical size of striped) and number of pixels between corresponding relationship, formed relational model:Wherein, i is
Striped group #；diIt is the width of the target striped in i-th of striped group；Be width be diTarget striped corresponding to picture
Plain number；Be width be diTarget striped corresponding to scale factor.Due to diWithIt is known that therefore marriage relation model
(1) scale factor corresponding to the target striped of each width grade can be calculatedValue.
Calibration modeling process is completed as a result,.
S506, the number of pixels p in conjunction with corresponding to the target striped of different in width d are determined and bubble diameter to be measured
The immediate target striped of corresponding number of pixels p'.
In the present embodiment, first by the striped group of N number of different in width grade according to corresponding to its width of fringe d
Number of pixels p is arranged successively with sequence from small to large, forms N+1 section.Wherein, picture corresponding to the smallest striped of width
Plain numberFirst section is formed with 0Number of pixels corresponding to the maximum striped of widthWith+∞ shape
At between tail regionN-1 intermediate section is formed by two adjacent number of pixels, i.e.,It is illustrated by taking resolving power test target 1 shown in Fig. 3 as an example, due in Fig. 3
Shown in be etched with the striped group of 4 width grades on resolving power test target 1, i.e., the target striped of corresponding 4 different in width, so as to
With corresponding 4 number of pixels, respectively P10、P20、P50、P100, can then form 5 sections: (0, P10)、(P10, P20)、
(P20, P50)、(P50, P100)、(P100,+∞).
Where finding out the immediate target striped of number of pixels p' corresponding to number of pixels p and bubble diameter to be measured
During striped group j, first determine whether that the p' is fallen into the section of which of the N+1 section.If the p' is fallen into
First sectionIt is interior, then by target striped corresponding to the 1st striped group be determined as with corresponding to bubble diameter to be measured
The immediate target striped of number of pixels p'；If the p' is fallen between tail regionIt is interior, then by n-th striped
The corresponding target striped of group is determined as and the immediate target striped of number of pixels p' corresponding to bubble diameter to be measured；If described
P' is fallen into N-1 intermediate section, then calculates separately the number of pixels of the p' and two endpoints in the section
Relative error, choose the lesser number of pixels of relative error as closest with the p', then determine with it is to be measured
The immediate target striped of number of pixels p' corresponding to bubble diameter.
S507, using relational model corresponding to the target striped determined, Inversion Calculation goes out the reality of bubble diameter to be measured
Border physical size d'.
In the present embodiment, the target striped finally determined according to step S506 determines institute's relationship mould to be used
TypeAnd then number of pixels p' corresponding to bubble diameter to be measured is substituted into the relational model, due to ratio
The factorIt is known that the actual physical size d' of the partial size of bubble to be measured thus can be calculated.
Specifically, if the p' falls into first sectionIt is interior, then utilize relational modelIt calculates
The actual physical size d' of the bubble diameter out, i.e.,
If the p' is fallen between tail regionRelational model that is interior, then utilizingIt calculates
The actual physical size d' of the bubble diameter, i.e.,
If the p' falls into some intermediate sectionIt is interior, then calculate separately the two of the p' and the section
The number of pixels of a endpointRelative error, that is,
Compare relative errorNumber of pixels corresponding to choosing relative error lesser one, determines institute
The relationship module that need to be used, and then calculate the actual physical size d' of the bubble diameter.Assuming that number of pixels is immediate
Striped group where target striped is striped group j, then utilizes relational model corresponding to j-th of striped group
Calculate the actual physical size of the bubble diameter
The accurate calculating to the particle size parameters of bubble to be measured is just completed as a result,.
Below by a specific example, the bubble diameter Inversion Calculation method of the present embodiment is illustrated.
By taking resolving power test target 1 shown in fig. 6 and target stripe pattern shown in Fig. 8 as an example, concrete example is described as follows:
(1) resolving power test target 1 is placed in water body, adjusts the position of industrial camera in operating distance；
(2) position for adjusting resolving power test target 1, by width d2=20 μm of striped group is placed in the field range of industrial camera
It is interior；
(3) start industrial camera and telecentric lens shoot this group of striped, form target stripe pattern as shown in Figure 8；
(4) method for using image procossing, obtains the width d of four target stripeds in target stripe pattern respectively2Institute is right
The number of pixels p answered20, for example, respectively 5,5,6,5；
(5) to four above-mentioned number of pixels averageds, as width d2Corresponding to=20 μm of target striped
Number of pixels
(6) width d is calculated2Scale factor corresponding to=20 μm of target stripedIt protects
Deposit p20=5.25 and a20=0.2625；
(7) width is d by the position for adjusting resolving power test target 11、d3、d4Striped group be sequentially placed into the visual field of industrial camera
In range, then calculating separately out width according to step (3)-(6) is d1=10 μm, d3=50 μm, d4=100 μm of target item
Scale factor corresponding to line:
And save p10=3.33, a10=0.3333；p50=10.39, a50=0.2078；p100=22.48, a100=
0.2248；
(8) according to the 4 of preservation number of pixels P10、P20、P50、P100, mark off 5 sections: (0, P10)、(P10, P20)、
(P20, P50)、(P50, P100)、(P100,+∞)；
(9) the bubble image that water body to be measured is obtained using the industrial camera and telecentric lens, extracts bubble profile；
(10) number of pixels p' corresponding to the partial size of bubble to be measured is calculated using the method for image procossing；Assuming that p'=
8, then determine that the section belonging to it is (P20, P50), i.e., (5.25,10.39)；
(11) p' and P are calculated separately20、P50Relative error:
(11) compare relative error σ20、σ50, choose the lesser number of pixels P of relative error50Corresponding scale factor
a50；
(12) by p'=8 and scale factor a50Substitute into relationship module corresponding to the target striped that width is 50 μm
Calculate the physical size of the partial size of the bubble to be measured
Certainly, the above is only a kind of preferred embodiment of the invention, it is noted that for the general of the art
For logical technical staff, various improvements and modifications may be made without departing from the principle of the present invention, these improve and
Retouching also should be regarded as protection scope of the present invention.
Claims (5)
1. a kind of equivalent grain size conversion method of aspherical bubble characterized by comprising
Water body to be measured is shot, obtains bubble image, and extract bubble profile；
For each bubble profile, the center-of-mass coordinate of the bubble profile is calculated, formula is as follows:
Wherein, (xc,yc) it is center-of-mass coordinate, NbIt is the sum of profile and border pixel, (xi,yi) be profile and border point coordinate；
Using the mass center as coordinate origin, plane right-angle coordinate is established, calculates separately out the bubble profile in X-axis and Y-axis
Number of pixels corresponding to radius on direction, and it is denoted as r respectivelyx、ry；
If rx≠ry, then determine that the bubble is aspherical bubble, select r respectivelyxAnd ryIt is straight in space as the bubble profile
Number of pixels r corresponding to radius in angular coordinate system in Z-directionz, according to ellipsoid calculation formula:Meter
Calculate two ellipsoid volumes；
Seek volume V of the average value of two ellipsoid volumes as the aspherical bubble；
Utilize spherical volume formulaCalculate number of pixels p' corresponding to the equivalent grain size of the aspherical bubble
=r；
Inversion Calculation, including following procedure are carried out to bubble diameter:
The striped group of N number of different in width grade is set on resolving power test target, and the N is the positive integer greater than 1；By it is described it is N number of not
Striped group with width grade is arranged successively according to number of pixels corresponding to its width of fringe with sequence from small to large, is formed
N+1 section；Wherein, number of pixels corresponding to the smallest striped of widthFirst section is formed with 0Width is most
Number of pixels corresponding to big stripedIt is formed between tail region with+∞N-1 intermediate section is by adjacent
Two number of pixels are formed, i.e.,
The resolving power test target is immersed in water body, the striped group on the resolving power test target is shot, forms target bar graph
Picture；
Number of pixels corresponding to the width of target striped is calculated according to the target stripe pattern；
For the striped group of each width grade, the width of target striped and the corresponding relationship of number of pixels are established, is formed and is closed
It is model:Wherein, i is striped group #, diIt is the width of the target striped in i-th of striped group,It is
Width is diTarget striped corresponding to number of pixels,Be width be diTarget striped corresponding to scale factor；
Judge that the p' is fallen into the section of which of the N+1 section；
If the p' falls into first sectionIt is interior, then utilize relational model corresponding to the 1st striped groupCalculate the physical size of the bubble diameter
If the p' is fallen between tail regionIt is interior, then utilize relational model corresponding to n-th striped groupCalculate the physical size of the bubble diameter
If the p' is fallen into some intermediate section, the number of pixels of the p' and two endpoints in the section are calculated separatelyRelative error, and choose relational model corresponding to the lesser number of pixels of relative error and calculate institute
State the physical size of bubble diameterJ=i or i+1.
2. the equivalent grain size conversion method of aspherical bubble according to claim 1, which is characterized in that calculating the rx、
ryDuring, if rx=ry, then determine that the bubble for spherical bubbles, directly generates picture corresponding to the partial size of the bubble
Plain number p'=rx。
3. the equivalent grain size conversion method of aspherical bubble according to claim 1 or 2, which is characterized in that at each
The linear fringe of M equal in width is provided in the striped group, the M is the positive integer greater than 1；Described in the shooting
The striped group on resolving power test target, during forming target stripe pattern, comprising:
The linear fringe of M equal in width in one of striped group, is placed in the visual field of shooting by the position for adjusting resolving power test target
In range, target stripe pattern corresponding to the striped group is formed；
Change the position of the resolving power test target, the linear fringe of M equal in width in remaining each striped group is successively placed in bat
In the field range taken the photograph, one-to-one N number of target stripe pattern therewith finally is formed for N number of striped group.
4. the equivalent grain size conversion method of aspherical bubble according to claim 3, which is characterized in that N number of item
Line group from bottom to top parallel arrangement on the resolving power test target；In each striped group, the linear fringe of a plurality of equal in width
It is vertical line striped, and be in line in parallel.
5. the equivalent grain size conversion method of aspherical bubble according to claim 3, which is characterized in that described according to institute
It states during target stripe pattern calculates number of pixels corresponding to the width of target striped, comprising:
Pixel corresponding to its width is calculated separately out for the linear fringe of M equal in width in each target stripe pattern
Number, and to M number of pixels averaged of acquisition, it is denoted as number of pixels corresponding to the width of the target striped.
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