CN100359286C - Method for improving laser measuring accuracy in image processing - Google Patents

Abstract

The present invention relates to a method for increasing laser measurement precision, particularly to a method for improving laser measuring accuracy in image processing. A laser emission device (4), a light source image collecting device (1) and a computer (11) are used by the method for increasing laser measurement precision. When the laser (3) of the laser emission device (4) is aligned to the light source image collecting device (1), data of an image and a position of a light spot (2) of the laser (3) are collected by the light source image collecting device (1), and the image is stored into the computer (11) through a datum transmission line (10). The present invention is characterized in that according to the color of the laser (3), the component of a corresponding color is used as the component of the laser (3) to solve for an equalizing value and a maximal value of the component of the collected image. A threshold value is taken between the equalizing value and the maximal value to obtain a laser light spot picture. Image two-value division is carried out on the light spot to obtain a two-value image and a calculated barycenter center, and a coordinate of the barycenter is used as the coordinate of the light spot. The present invention has the advantages of laser measurement precision improvement and reduction of measuring calculation erroneous judgment to the light spot by the computer.

Description

Flame Image Process improves the method for laser measurement precision

Technical field

The present invention relates to a kind of method that improves the laser measurement precision, especially can improve the method for alignment measurement precision.

Background technology

At present, the general technology scheme is adopting a generating laser and a receptacle, and by the position that circuit such as SD, CCD, MOS are gathered laser facula, its principle is to utilize the variation of photodiode surface impedance under the light conditions to detect the position of hot spot.Then image signal transmission is carried out Flame Image Process work in computing machine, hot spot is cut apart with background.Therefore the partitioning algorithm that has now proposed does not have a kind of general partitioning algorithm that is suitable for all images mostly at particular problem.General characteristics [the leaf good reputation that distributes at gaussian laser, the application [M] of laser in delicate metering, China Machine Press's publication date: July in 1980 the 1st edition], adopt the characteristics of Gaussian distribution that image is carried out convolution, survey the energy distribution of hot spot, obtain the coordinate position of hot spot.But because the variable in distance hot spot of measuring deforms, not exclusively according to the characteristics of Gaussian distribution, the inner brightness of hot spot is skewness often, influences the center that Flame Image Process is measured hot spot for the laser Luminance Distribution sometimes.Generally in laser measurement, just hot spot is carried out contraposition, and hot spot has a certain size, it is also not necessarily even to distribute, and the character of hot spot can influence the precision of measurement.

Summary of the invention

For the characteristics that overcome existing Gaussian distribution image is carried out the deficiency of convolution, the invention provides a kind of image processing method, this method measuring accuracy height.

Technical scheme of the present invention is:

The present invention utilizes laser beam emitting device 4 and light source image harvester 1, the emission laser radiation is to light source image harvester 1, because laser beam emitting device 4 is installed on the different parts with light source image harvester 1, when laser beam emitting device 4 and light source image harvester carrier generation relative motion, perhaps angle of arrival deviation, the spot of laser departs from the reference position, and this device is by measuring the relative space position and the error that depart from two different parts of measurement of coordinates of hot spot.

Light source image harvester 1 mainly is hot spot 2 placement data acquisition to laser, the light source image harvester can adopt PSD, CCD, circuit such as MOS gather the position of laser facula, and its principle is to utilize the variation of photodiode surface impedance under the light conditions to detect the position of hot spot 2.Image and position that this method is gathered hot spot 2 by light source image harvester 1, with image storage in computing machine, according to the color of laser, as the laser of redness, then adopt the red component of RGB, obtain the average and the maximum value of the component (brightness) of images acquired, between average and maximum value, get a threshold value, obtain laser facula figure, hot spot is carried out the image two-value to be cut apart, obtain bianry image, the center of gravity center of calculating, with the coordinate of center of gravity as the hot spot coordinate.

In order further to improve measuring accuracy, reduce the erroneous judgement of computing machine to hot spot, set up (2*N+1) * (2*N+1) template pixel 6 of hot spot, these template 6 sizes are odd number, help obtaining the center of hot spot, obtain representation of laser facula, obtain the distribution of the size and the light intensity of laser facula 2, as convolution operator.Then in measurement, in order to measure the position of hot spot accurately, gather the image of the laser of measuring by light source image harvester 1, then the image and the hot spot module of abrasive particle are carried out convolution algorithm, obtain matrix, again this matrix is built the size that obtains original measurement matrix.Convolution is built the position of the maximum value of back matrix for the hot spot of measurement, the size of hot spot originally is a saturated color, hot spot is to be made of many extreme values, the three-dimensional plot of hot spot is a more flat Luminance Distribution, carry out intensity map after the process of convolution now and be one relatively the distributed in three dimensions precision of point be improved.

The invention has the beneficial effects as follows: improve the precision of laser measurement, reduce two erroneous judgements of calculating hot spot.

Method of the present invention is directly gathered hot spot from LASER SPECKLE distributed data as template window, carries out convolution by this template to image, and the position of laser measurement hot spot is located more accurately, has greatly improved the laser measurement precision.

Description of drawings

The present invention is further described below in conjunction with drawings and Examples.

Fig. 1 is a fundamental diagram of the present invention

Fig. 2 is that binaryzation LASER SPECKLE centre coordinate is determined figure

Fig. 3 is the image graph that light source image harvester of the present invention is gathered LASER SPECKLE

Fig. 4 is the image intensity distribution plan that light source image harvester of the present invention is gathered LASER SPECKLE

Fig. 5 is LASER SPECKLE template figure of the present invention

Fig. 6 is a LASER SPECKLE template light distribution distribution plan of the present invention

Fig. 7 is the moment of distribution system of battle formations after the process of convolution of the present invention

Fig. 8 is matrix pruning figure after the process of convolution of the present invention

Fig. 9 is that the present invention adds the frosted glass schematic diagram

Among the figure: 1. light source image harvester, 2. hot spot, 3. laser, 4. laser beam emitting device (collimator apparatus), 5. hot spot coordinate, 6. template, 7. frosted glass, 8. lens 9. position detection devices, 10. data line, 11. computing machines.

Embodiment

Embodiment 1: Flame Image Process improves the method 1 of laser measurement precision:

As shown in Figure 1 and Figure 2, utilize laser beam emitting device 4, light source image harvester 1 and computing machine 11, the emission laser radiation is to light source image harvester 1, because laser beam emitting device 4 is installed on the different parts with light source image harvester 1, when laser beam emitting device 4 and light source image harvester carrier generation relative motion, perhaps angle of arrival deviation, the spot of laser departs from the reference position, and light source image harvester 1 is by measuring the relative space position and the error that depart from two different parts of measurement of coordinates of hot spot.When the laser alignment light source image harvester 1 of generating laser 4, light source image harvester 1 mainly is image and the placement data acquisition to the hot spot 2 of laser 3, the light source image harvester can adopt PSD, CCD, circuit such as MOS are gathered the position of hot spot 2, and its principle is to utilize the variation of photodiode surface impedance under the light conditions to detect the position of hot spot.Image and position that this method is gathered laser facula 2 by light source image harvester 1, by data line 10 with image storage in computing machine 11, according to the color of laser,, then adopt the red component of RGB as the laser of redness; When laser is that green is, then adopt the green component of RGB; When laser is Lan Seshi, then adopt the blue colouring component of RGB.Might as well establish laser for red, have:

$R=\left(\begin{array}{cccc}p\left(\mathrm{1,1}\right)& p\left(\mathrm{1,2}\right)& \·\·\·& p(1,x)\\ p\left(\mathrm{2,1}\right)& p\left(\mathrm{2,2}\right)& \·\·\·& p(2,x)\\ \·\·\·& & & \·\·\·\\ p(i,y)& & \·\·\·& p(x,y)\end{array}\right)$

Wherein, R is certain spot image color component matrix;

The average of red component is:

$R_{\mathrm{mean}}=\frac{1}{\mathrm{xy}}\underset{i=x}{\overset{1}{\mathrm{\Σ}}}\underset{j=y}{\overset{1}{\mathrm{\Σ}}}p(i,j)$

P (i j) is the brightness value of R matrix pixel,

The maximum value of red component is:

R _max＝MAX(P(i，j)|1≤i≤x，1≤j≤y)

Getting threshold value between average and maximum value is:

R _mean＜T≤R _max

Threshold value generally can for:

$R_{\mathrm{mean}}+\frac{3}{4}(R_{\max }-R_{\mathrm{mean}})\≤T\≤R_{\mathrm{mean}}+\frac{4}{5}(R_{\max }-R_{\mathrm{mean}})$

Passing threshold carries out binaryzation to image, and laser facula 2 is carried out image segmentation, promptly obtains binaryzation matrix G, that is:

G＝(R≥T)

Obtain bianry image (as shown in Figure 2), calculate hot spot center of gravity center, with the coordinate of center of gravity as the hot spot coordinate.

According to calculation formula of gravity centre, at first calculate the pixel number of hot spot, remove each abrasive particle rectangular coordinate sum in this abrasive particle more respectively, promptly can obtain hot spot barycentric coordinates (center_x, center_y).

$\mathrm{center}\_x=\frac{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{G}_{\mathrm{ix}}\right)}{n},i=\mathrm{1,2,3}...$

$\mathrm{center}\_y=\frac{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{G}_{\mathrm{iy}}\right)}{n},i=\mathrm{1,2,3}...$

N remarked pixel sum wherein, G _Ix, G _IyHorizontal stroke, the ordinate value of representing certain point.Because the position range of the hot spot of seeing originally is very big, naked eyes generally are difficult to accurately location, by the center of gravity location, the accuracy of measuring are improved.

Embodiment 2: Flame Image Process improves the method 2 of laser measurement precision:

As Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, shown in Figure 7, in order further to improve measuring accuracy, before carrying out center of gravity calculation, at first light spot image is carried out pre-service, reduce the erroneous judgement of computing machine to hot spot, at the beginning of not measuring, earlier laser 3 is shone on the light source image harvester 1, the light source image harvester collects laser radiation to light source image harvester light spot image, on method 1 basis, find hot spot center of gravity (center_x, center_y), determine the center of hot spot 2, set up the m of hot spot ₂* n ₂Hot spot template pixel matrix W obtains representation of laser facula template 6, and wherein matrix W is to be the positive matrices in center with the hot spot center of gravity, it in the brightness of matrix W brightness value corresponding among the former hot spot figure matrix R, obtain the distribution of the size and the light intensity of laser facula 2, as convolution operator, i.e. hot spot module.Then in measurement, in order to measure the position of hot spot accurately, gather the image of the laser of measuring by light source image harvester 1, image and the hot spot pattern matrix w with laser carries out convolution algorithm then,

For size is m ₁* n ₁Hot spot digital picture matrix R (x, y) and size be m ₂* n ₂Hot spot template pixel matrix w (impulse response function) carries out the two-dimensional digital image convolution algorithm, and discrete formula has:

Z(i，j)＝R(x，y)*w(i，j)

＝∑∑(R(m，n)*w(i-m，j-n))

R is the light spot image matrix, and w is a hot spot template pixel matrix,

The matrix size that wherein obtains is M * N, M=m ₁+ m ₂-1, N=n ₁+ n ₂-1.

Obtain matrix Z, generally by the matrix row and column after the convolution respectively than original big m ₂-1 and n ₂-1, matrix Z ranks must be reduced m respectively ₂-1 and n ₂-1, be about to matrix both sides up and down, the right and left reduces (m respectively ₂-1)/2 with (n ₂-1)/2.Work as m ₂-1 or n ₂-1 is odd number when counting, and the both sides adjustment of matrix is asymmetric 1 row or column that differs, and obtains the big or small Z ' of original measurement matrix like this.Convolution is built the position of the maximum value of back matrix for the hot spot of measurement

Z _max′＝MAX(Z′(i，j)|1≤i≤x，1≤j≤y)

Z is a matrix,

The size of hot spot originally is a saturated color, hot spot is to be made of many extreme values, the three-dimensional plot of hot spot is a more flat Luminance Distribution, carry out intensity map after the process of convolution now and be one relatively the distributed in three dimensions precision of point be improved, difference has also been drawn back, and the peak value of hot spot becomes more obvious.And then by calculating position that the hot spot center of gravity searches hot spot promptly.

$\mathrm{center}\_x=\frac{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{Z^{\′}}_{\mathrm{ix}}\right)}{n},i=\mathrm{1,2,3}...$

$\mathrm{center}\_y=\frac{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{Z^{\′}}_{\mathrm{iy}}\right)}{n},i=\mathrm{1,2,3}...$

Embodiment 3: Flame Image Process improves the method 3 of laser measurement precision: as shown in Figure 8,

According to method 2, set up the m of hot spot ₂* n ₂Template pixel, this template size are odd number, that is: m ₂=2 * k+1, n ₂=2 * s+1, (i j) carries out after the convolution algorithm, and matrix size is: M=m to hot spot digital picture f ₁+ m ₂-1=m ₁+ 2 * k, N=n ₁+ n ₂-1=n ₁+ 2 * s.Matrix has increased by 2 * k, 2 * s respectively in different directions.When measuring, need reduce respectively up and down k, about reduce s respectively, recover original size, in the accurate position of measuring hot spot.K removes the number of pixel for both sides up and down, and s is the number that the right and left removes pixel.

Embodiment 4: Flame Image Process improves the method 4 of laser measurement precision:

As shown in Figure 9, in order to reduce the influence of ambient light, before light source image harvester 1, add a frosted glass 7, light source image harvester 1, frosted glass 7, lens 8 are positioned on the position detection device 9 same optical axises, and with laser beam emitting device 4 same optical axises, lens 8 are between light source image harvester 1 and frosted glass 7, and light source image harvester 1 is connected with computing machine 11 by data line 10.Hot spot scioptics on the frosted glass of laser radiation are imaged onto light source image harvester 1, by data line image are transferred in the computing machine.Frosted glass 7 reduces influence and surrounding environment in image collecting device the imaging of ambient light to light source image harvester 1, enlarge the image acquisition scope of light source image harvester 1, avoided the electronic component in the direct projection infringement light source image harvester 1 of laser.

Claims (6)

1. Flame Image Process improves the method for laser measurement precision, this method is utilized laser beam emitting device (4), light source image harvester (1) and computing machine (11), when laser (3) the alignment light source image collecting device (1) of generating laser (4), light source image harvester (1) is to the image and the placement data acquisition of the hot spot (2) of laser (3), by data line (10) image storage is arrived in the computing machine (11), it is characterized in that: according to the color of laser (3), laser (3) component adopts the component of respective color, obtain the average and the maximum value of the component of images acquired, between average and maximum value, get a threshold value, obtain laser facula figure, hot spot is carried out the image two-value to be cut apart, obtain bianry image, calculate the hot spot center of gravity, with the coordinate of center of gravity as the hot spot coordinate.

2. Flame Image Process according to claim 1 improves the method for laser measurement precision, and it is characterized in that: this method asks the average of laser (3) component to be:

$R_{\mathrm{mean}}=\frac{1}{\mathrm{xy}}\underset{i=x}{\overset{1}{\mathrm{\Σ}}}\underset{j=y}{\overset{1}{\mathrm{\Σ}}}p(i,j)$

R is the light spot image matrix, and (i j) is the brightness value of R matrix pixel to p;

The high-high brightness of light spot image matrix R pixel is

R _max＝MAX(P(i，j)|1≤i≤x，1≤j≤y)

Getting threshold value between average and maximum value is:

R _mean＜T≤R _max

Passing threshold T carries out binaryzation to image, and laser facula (2) is carried out image segmentation, promptly obtains binaryzation matrix G, that is:

G＝(R≥T)

Obtain bianry image, calculate the hot spot center of gravity, with the coordinate of center of gravity as the hot spot coordinate;

At first calculate the pixel number of hot spot, remove each hot spot rectangular coordinate sum in this hot spot more respectively, promptly can obtain hot spot barycentric coordinates (center_x, center_y),

$\mathrm{center}\_x=\frac{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{G}_{\mathrm{ix}}\right)}{n},i=\mathrm{1,2,3}...$

$\mathrm{center}\_y=\frac{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{G}_{\mathrm{iy}}\right)}{n},i=\mathrm{1,2,3}...$

N remarked pixel sum wherein, G _Ix, G _IyHorizontal stroke, the ordinate value of representing certain point.

3. Flame Image Process according to claim 2 improves the method for laser measurement precision, and it is characterized in that: threshold value is:

$R_{\mathrm{mean}}+\frac{3}{4}(R_{\max }-R_{\mathrm{mean}})\≤T\≤R_{\mathrm{mean}}+\frac{4}{5}(R_{\max }-R_{\mathrm{mean}}).$

4. Flame Image Process according to claim 1 improves the method for laser measurement precision, it is characterized in that: before carrying out the hot spot center of gravity calculation, at first light spot image is carried out pre-service, at the beginning of not measuring, earlier laser (3) is shone on the light source image harvester (1), light source image harvester (1) collects the light spot image of laser radiation to the light source image harvester, find hot spot center of gravity (center_x, center_y), determine the center of gravity of hot spot (2), set up the m of hot spot ₂* n ₂The template pixel matrix W, obtain representation of laser facula template (6), wherein matrix W is to be the positive matrices in center with the hot spot center of gravity, each pixel of matrix W is a brightness value corresponding among the former light spot image matrix R, obtain the size of laser facula (2) and the distribution of light intensity, as convolution operator, i.e. hot spot module; Then in measurement, in order to measure the position of hot spot accurately, the image of the laser of measuring by light source image harvester (1) collection carries out convolution algorithm with the image and the hot spot template pixel matrix W of laser then,

For size is m ₁* n ₁Hot spot digital picture matrix R (x, y) and size be m ₂* n ₂Hot spot template pixel matrix W is carried out the two-dimensional digital image convolution algorithm, and discrete formula has:

Z(i，j)＝R(x，y)*w(i，j)

＝∑∑(R(m，n)*w(i-m，j-n))

R is the light spot image matrix, and W is a hot spot template pixel matrix,

The matrix size that wherein obtains is M * N, M=m ₁+ _m2-1, N=n ₁+ n ₂-1;

Obtain matrix Z, by the matrix row and column after the convolution respectively than original big m ₂-1 and n ₂-1, matrix Z ranks must be reduced m respectively ₂-1 and n ₂-1, be about to matrix both sides up and down, the right and left reduces (m respectively ₂-1)/2 with (n ₂-1)/2; Work as m ₂-1 or n ₂-1 is odd number when counting, and the both sides adjustment of matrix is asymmetric 1 row or column that differs, and obtains the big or small Z ' of original measurement matrix like this; Convolution is built the position of the maximum value of back matrix for the hot spot of measurement,

Z′ _max＝MAX(Z′(i，j)|1≤i≤x，1≤j≤y)

And then by calculating position that the hot spot center of gravity searches hot spot promptly,

$\mathrm{center}\_x=\frac{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{Z^{\′}}_{\mathrm{ix}}\right)}{n},i=\mathrm{1,2,3}...$

$\mathrm{center}\_y=\frac{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{Z^{\′}}_{\mathrm{iy}}\right)}{n},i=\mathrm{1,2,3}....$

5. Flame Image Process according to claim 4 improves the method for laser measurement precision, it is characterized in that: the m that sets up hot spot ₂* n ₂Template pixel, this template size are odd number, that is: m ₂=2 * k+1, n ₂=2 * s+1, (i j) carries out after the convolution algorithm, and matrix size is: M=m to hot spot digital picture f ₁+ m ₂-1=m ₁+ 2 * k, N=n ₁+ n ₂-1=n ₁+ 2 * s; Matrix has increased by 2 * k, 2 * s respectively in different directions; When measuring, need reduce respectively up and down k, about reduce s respectively, recover original size, in the accurate position of measuring hot spot, k removes the number of pixel for both sides up and down, s is the number that the right and left removes pixel.

6. Flame Image Process according to claim 1 improves the method for laser measurement precision, it is characterized in that: at the preceding frosted glass (7) that adds of light source image harvester (1), be provided with lens (8) between light source image harvester (1) and the frosted glass (7), hot spot scioptics (8) on the frosted glass of laser radiation (7) are imaged onto light source image harvester (1), by data line with the light spot image data transmission in computing machine.

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