CN107274393B - Monocrystaline silicon solar cell piece detection method of surface flaw based on grid line detection - Google Patents

Monocrystaline silicon solar cell piece detection method of surface flaw based on grid line detection Download PDF

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CN107274393B
CN107274393B CN201710438495.XA CN201710438495A CN107274393B CN 107274393 B CN107274393 B CN 107274393B CN 201710438495 A CN201710438495 A CN 201710438495A CN 107274393 B CN107274393 B CN 107274393B
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CN107274393A (en
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钱晓亮
张鹤庆
李清波
杨存祥
张焕龙
毋媛媛
刁智华
刘玉翠
吴青娥
陈虎
贺振东
过金超
王延峰
姜利英
张秋闻
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Zhengzhou University of Light Industry
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    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00Image analysis
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    • G06T7/0004Industrial image inspection
    • G06T7/0008Industrial image inspection checking presence/absence
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T3/00Geometric image transformations in the plane of the image
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    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
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Abstract

The present invention proposes a kind of monocrystaline silicon solar cell piece detection method of surface flaw based on grid line detection, and its step is as follows:First, monocrystaline silicon solar cell piece surface image is pre-processed using image scaling and medium filtering;Secondly, a kind of grid line detection method is proposed, for deleting main gate line and secondary grid line in monocrystaline silicon solar cell piece surface image;Then, a kind of super-pixel segmentation and the method that adaptive thresholding is combined are proposed, for detecting defect area in without grating figure picture, obtains initial testing result figure;Finally, initial detecting result figure is post-processed by image scaling, obtains final testing result figure.The present invention not only requires relatively low to the acquisition quality of monocrystaline silicon solar cell piece surface image, and there is faster detection speed while keeping compared with high detection accuracy rate, it is significant to the quality inspection efficiency and ex factory pass rate of raising monocrystaline silicon solar cell piece.

Description

Monocrystaline silicon solar cell piece detection method of surface flaw based on grid line detection
Technical field
The present invention relates to the technical field of the surface defects detection based on machine vision, is mainly based upon the list that grid line detects Crystal silicon solar batteries piece detection method of surface flaw.
Background technology
The essence of monocrystaline silicon solar cell piece surface defects detection is whether to judge monocrystaline silicon solar cell piece surface Existing defects and the position of positioning defect areas.In recent years, solar energy power generating turned into the master for solving problem of energy crisis One of scheme is wanted, while the quality of solar cell tablet quality directly affects the efficiency of photovoltaic generation again, therefore, to solar-electricity It is significant that pond piece surface carries out defects detection.
Solar battery sheet surface defects detection based on machine vision is current Main Trends of The Development, and prior art is equal It is that various types of mathematical modeling is established to carry out defects detection according to the feature of defect, for example, based on Gradient Features, gathering The mathematical modelings such as class algorithm, frequency-domain analysis, matrix decomposition and machine learning.However, all there is generalization ability deficiency in these methods The problem of, i.e.,:The detection of a few class defects is only applicable to, for example, the detection method based on Gradient Features and clustering algorithm is applicable Detected in the defects of crackle and disconnected grid type, the detection method based on frequency-domain analysis and matrix decomposition is more suitable for strip and distribution The defects of more scattered, is detected.
The content of the invention
For the technology of the existing solar battery sheet detection method of surface flaw generalization ability deficiency based on machine vision Problem, the present invention proposes the monocrystaline silicon solar cell piece detection method of surface flaw based on grid line detection, according to monocrystalline silicon The characteristics of solar battery sheet surface texture, the master in monocrystaline silicon solar cell piece surface image is deleted by grid line detection Grid line and secondary grid line, meanwhile, examined using the method that super-pixel segmentation and adaptive thresholding are combined in without grating figure picture Survey defect area.
In order to solve the above-mentioned technical problem, the technical scheme is that:Mono-crystalline silicon solar electricity based on grid line detection Pond piece detection method of surface flaw, it is characterised in that its step is as follows:One) using image scaling and medium filtering to monocrystalline silicon Solar battery sheet surface image is pre-processed;Two) detected by grid line and delete monocrystaline silicon solar cell piece surface image In main gate line and secondary grid line;Three) detected and lacked in without grating figure picture using super-pixel segmentation and adaptive thresholding method Region is fallen into, obtains initial detecting result figure;Four) initial detecting result figure is post-processed by image scaling, obtained final Testing result figure.
The pretreatment includes greyscale image transitions, image scaling and median filter method:
1) greyscale image transitions:The monocrystaline silicon solar cell piece surface image collected is converted into gray level image, obtained The gray level image arrived is I1
2) image scaling:By the gray level image I that size is m × n1Equal proportion scaling is carried out, it is k × g's to obtain resolution ratio Zoomed image I2;Wherein, scaling is r ∈ (0,1), k=round (m × r), g=round (n × r), round () generation Table rounds up computing, and m, n, k, g are nonnegative integers, and m, n represent gray level image I1Line number and columns, k, g represent scaling Image I2Line number and columns;
3) image noise reduction:Using median filter method to zoomed image I2Noise reduction is carried out, removes what detection was had a great influence Impulsive noise, the image tagged after noise reduction is I, and resolution ratio is k × g.
The median filter method is to zoomed image I2Carrying out the method for noise reduction is:Define the pixel that coordinate is (x, y) Neighborhood be:
Nx,y(R)=(i, j) | | i-x |≤R, | j-y |≤R } (1)
Wherein, R is positive integer, represents the radius of neighborhood, and (i, j) represents the coordinate of pixel in neighborhood, Nx,y(R) represent Using centered on pixel (x, y), radius as all pixels point in R neighborhood coordinate set;
Medium filtering is carried out to pixel (x, y), its result is:
I (x, y)=Median { I2(i,j),(i,j)∈Nx,y(R)} (2)
Wherein, I (x, y) be pixel (x, y) medium filtering after gray value, I2(i, j) is zoomed image I2Middle coordinate is The gray value of the pixel of (i, j), Median { } are to take median operation;
The R=1 of formula (2);Utilize formula (2) traversal zoomed image I2All pixels point can obtain image I.
The side that the main gate line and secondary grid line deleted in monocrystaline silicon solar cell piece surface image are detected by grid line Method is:
1) the gray scale sum of each row and columns of image I is calculated:
Wherein, xth row in I (x, y) representative image I, at y row pixel gray value, SHxRepresent all pictures of image I xth rows The gray scale of element and SLyRepresent image I y row all pixels gray scale and;
2) position of main gate line and secondary grid line is detected:
Wherein, ZX represents the row coordinate set where main grid line position in image I, and ZY represents secondary grid line position in image I The row coordinate set at place;If the gray scale and SH of xth rowxMore than or equal to the average value of all row gray scale sumsThen Xth row is the row that main gate line is sitting in, and now, the coordinate " x " of this line is brought into set ZX;If y row gray scale and SLyMore than or equal to the average value of all row gray scale sumsThen y row are the row that secondary grid line is sitting in, and now, this is arranged Coordinate " y " bring into set ZY;
3) main gate line and secondary grid line are deleted:
According to the instruction of row coordinate in row coordinate set ZX, corresponding row is deleted from image I, realizes and deletes main grid Line;According to the instruction of row coordinate in row coordinate set ZY, corresponding row are deleted from image I, realizes and deletes secondary grid line;Main grid Image tagged after line and secondary grid line are deleted is image I', and its size is p × q, and p, q are positive integers, and p < k, q < g.
Defect area is detected in the no grating figure picture, the method for obtaining initial detecting result figure is:
1) super-pixel segmentation
Image segmentation, the area after segmentation are carried out to the image I' for deleting main gate line and secondary grid line using SLIC super-pixel algorithm Field mark is:F={ F1,F2,...,FT, wherein, T represents the quantity of cut zone, each cut zone from the upper left corner of image to The lower right corner is sorted successively, Fc, c ∈ [1, T] represent all pixels point that c-th of cut zone includes;
2) adaptive thresholding
A. each cut zone F is calculatedcAverage gray value be:
Wherein, I'(i, j) the i-th row in representative image I', at j row pixel gray value, M (Fc), c ∈ [1, T] are represented Cut zone FcAverage gray value, | Fc| represent cut zone FcThe number of middle pixel;
B. defect area is determined by threshold decision:
D(Fc), c ∈ [1, T] represent cut zone FcTesting result, represent cut zone F if 0cBelong to defect area Domain, otherwise cut zone FcBelong to non-defective region;
After obtaining the testing result of all cut zone, initial detecting result figure D is obtained, size is p × q.
The method of the post processing is:
Image scaling:Equal proportion image scale operation is performed in pretreatment stage, scaling is r ∈ (0,1), now will Initial detecting result figure D carries out the inverse operation of equal proportion image scaling according to former ratio r, obtains final detection result image M, M Size be h × l, h=round (p/r), l=round (q/r).M is bianry image, and the gray value of defect area is 0, non-to lack The gray value for falling into region is 1.
The present invention is detected using grid line detection and super-pixel segmentation to monocrystaline silicon solar cell piece surface defect, energy Enough to find rapidly and be accurately positioned the position of defect, advantage is:1) present invention is to monocrystaline silicon solar cell piece surface image Acquisition quality it is less demanding, coloured image and gray level image, image resolution ratio be not less than 600 × 600 or so;2) Detection speed of the present invention is very fast, and monolithic detection time is about 0.25s or so.The method can significantly improve monocrystaline silicon solar cell The detection efficiency of piece surface defect, there is important meaning to the quality inspection efficiency and ex factory pass rate for improving monocrystaline silicon solar cell piece Justice.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing There is the required accompanying drawing used in technology description to be briefly described, it should be apparent that, drawings in the following description are only this Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can be with Other accompanying drawings are obtained according to these accompanying drawings.
Fig. 1 is the structural representation of the present invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete Site preparation describes, it is clear that described embodiment is only part of the embodiment of the present invention, rather than whole embodiments.Based on this Embodiment in invention, the every other reality that those of ordinary skill in the art are obtained under the premise of creative work is not paid Example is applied, belongs to the scope of protection of the invention.
As shown in figure 1, a kind of monocrystaline silicon solar cell piece detection method of surface flaw based on grid line detection, specifically Implementation steps are as follows:
One) monocrystaline silicon solar cell piece surface image is pre-processed using image scaling and medium filtering.
Pretreatment:
1) greyscale image transitions:The monocrystaline silicon solar cell piece surface image collected is converted into gray level image, if Image is gray level image in itself, then keeps constant, and the gray level image for marking to obtain is I1
The effect of greyscale image transitions:The present processes design specifically for gray level image, and purpose is exactly to reduce Amount of calculation, because coloured image is three passages, 3 times of amount of calculation, it is contemplated that the image of collection is likely to be coloured image, Gray level image is likely to be, so first uniformly changing into gray level image.
2) image scaling:By the gray level image I that size is m × n1Equal proportion scaling is carried out, it is k × g's to obtain resolution ratio Zoomed image I2;Wherein, scaling is r ∈ (0,1), k=round (m × r), g=round (n × r), round () generation Table rounds up computing, and m, n, k, g are nonnegative integers, and m, n represent gray level image I1Line number and columns, k, g represent scaling Image I2Line number and columns.By the gray level image I that the size of input is 624 × 6241Equal proportion scaling is carried out, scaling is 0.2, obtain the zoomed image I that size is 125 × 1252
The purpose of image scaling is to reduce amount of calculation.Because being found by many experiments, resolution ratio (size) exceedes 600 × 600 image, Detection results are influenceed after narrowing down to 125 × 125 less, amount of calculation can also to be substantially reduced, so And if the original resolution inherently 125*125 of collection image, it is unworkable, because the quality of this image compares high score Resolution narrows down to that an equal amount of image is far short of what is expected, because the definition of full resolution pricture is higher, even narrows down to same Size, definition image still more less than original resolution are good.Therefore, the resolution ratio of image not preferably less than 600*600, although Also to be reduced during actual calculating below, but image scaling reduces amount of calculation.
3) image noise reduction:Using median filter method to zoomed image I2Carry out noise reduction and obtain image I, remove to detecting shadow Ring larger impulsive noise.
Define coordinate is for the pixel neighborhood of a point of (x, y):
Nx,y(R)=(i, j) | | i-x |≤R, | j-y |≤R } (1)
Wherein, R is positive integer, represents the radius of neighborhood, and (i, j) represents the coordinate of pixel in neighborhood, Nx,y(R) represent Centered on pixel (x, y), radius is the coordinate set of all pixels point in R neighborhood, such as:Nx,y(1) represent with (x, Y) 3 × 3 neighborhoods centered on, Nx,y(2) 5 × 5 neighborhoods centered on (x, y) are represented, by that analogy.
Medium filtering is carried out to pixel (x, y), its result is:
I (x, y)=Median { I2(i,j),(i,j)∈Nx,y(1)} (2)
Wherein, I (x, y) be pixel (x, y) medium filtering after gray value, I2(i, j) is zoomed image I2Middle coordinate is The gray value of the pixel of (i, j), Median { } is takes median operation, i.e.,:All elements in set are sorted by size, The element value of centre is taken as output result.
Utilize formula (2) traversal zoomed image I2All pixels point can obtain image I, I size and I2It is identical, and 125×125。
Two) main gate line and the secondary grid line in monocrystaline silicon solar cell piece surface image are deleted using grid line detection method.
Grid line is deleted:
1) the gray scale sum of each row and columns of image I is calculated:
Wherein, xth row in I (x, y) representative image I, at y row pixel gray value, SHxRepresent all pictures of image I xth rows The gray scale of element and SLyRepresent image I y row all pixels gray scale and.
2) position of main gate line and secondary grid line is detected:
Wherein, ZX represents the row coordinate set where main grid line position in image I, and ZY represents secondary grid line position in image I The row coordinate set at place.If the gray scale and SH of xth rowxMore than or equal to the average value of all row gray scale sumsThen Xth row is the row that main gate line is sitting in, and now, the coordinate " x " of this line is brought into set ZX;If y row gray scale and SLyMore than or equal to the average value of all row gray scale sumsThen y row are the row that secondary grid line is sitting in, and now, this is arranged Coordinate " y " bring into set ZY.
By input picture it can be found that the whether thicker main gate line of line direction, or secondary grid thinner on column direction Line, its gray value is all apparently higher than non-grid region, thus it is possible to by calculating the gray scale on row and column direction and to detect it , if the gray scale of grid line and non-grid region be averaged, it is clear that the larger grid region of gray scale is naturally larger than average.
3) main gate line and secondary grid line are deleted:
First, according to the instruction of row coordinate (row where main gate line) in row coordinate set ZX, by corresponding row from image I Middle removal, it is deletion main gate line to perform this operation;Then, according to row coordinate (row where secondary grid line) in row coordinate set ZY Instruction, corresponding row are removed from image I, it is to delete secondary grid line to perform this operation;Image mark after grid line deletion Image I' is designated as, resolution ratio is 117 × 90.
Three) defect area is detected in without grating figure picture using super-pixel segmentation and adaptive thresholding method, obtained Initial detecting result figure.
Defective area detection
1) super-pixel segmentation
For more accurate positioning defect areas, the present invention carries out image segmentation using super-pixel algorithm to image I', Result queue after segmentation is:F={ F1,F2,...,F800, wherein 800 represent the quantity of cut zone, each cut zone is from figure The upper left corner of picture is sorted successively to the lower right corner, Fc, c ∈ [1,800] represent all pixels point that c-th of region includes.The present invention Super-pixel segmentation can be realized by SLIC (Simple Linear Iterative Clustering) super-pixel algorithm (ACHANTA R,SHAJI A,SMITH K,et al.SLIC superpixels compared to state-of-the- art superpixel methods.IEEE transactions on pattern analysis and machine intelligence,2012,34(11):2274-2282.)。
2) adaptive thresholding
A. each cut zone F is calculatedcAverage gray value:
Wherein, I'(i, j) the i-th row in representative image I', at j row pixel gray value, M (Fc), c ∈ [1,800] generations Table cut zone FcAverage gray value, | Fc| represent cut zone FcThe number of middle pixel.
B. defect area is determined by threshold decision:
D(Fc), c ∈ (1,800) represent cut zone FcTesting result, represent cut zone F if 0cBelong to defect Region, otherwise cut zone FcBelong to non-defective region;
After obtaining the testing result of all cut zone, you can initial detecting result figure is obtained, labeled as D, size 117 × 90, it is clear that D is bianry image, and defective area grayscale value is 0, and area free from defect gray value is 1.
Four) initial detecting result figure is post-processed by image scaling, obtains final testing result figure.
Post processing:
Image scaling:Equal proportion image scale operation is performed in pretreatment stage, scaling 0.2 now will be initial Testing result figure D carries out the inverse operation of equal proportion image scaling according to former ratio 0.2, obtains final detection result image M, M's Size is 585 × 450, wherein, 585=round (117/0.2), 450=round (90/0.2).M is bianry image, defect area The gray value in domain is 0, and the gray value in non-defective region is 1.Above by input picture reduce purpose be in order to reduce amount of calculation, Here amplify again according to former ratio, it is therefore an objective to allow observer is clearer to observe defect area.
The present invention be used for implement hardware environment be:Intel (R) Core (TM) i5CPU 3.2G computers, 8GB internal memories, 1GB video memory video cards, the software environment of operation are:Matlab R2014b and Windows 7.The selected monocrystalline silicon sun of experiment Energy cell piece surface image is the gray level image of a width resolution ratio 624 × 624.The present invention is 624 × 624 in 100 width resolution ratio Monocrystaline silicon solar cell piece surface image on be tested checking, it is as a result as follows:
1) using the technology of the present invention can be detected with fast speed in monocrystaline silicon solar cell piece surface image Defect, the average detected time of each image is 0.25s or so.
2) the defects of can obtaining 99% using the present invention, detects accuracy, wherein, defects detection accuracy is defined as judging Monocrystaline silicon solar cell piece surface image of the quantity of correct monocrystaline silicon solar cell piece surface image with participating in detection The ratio between total quantity.Table 1 show the testing result statistics of 100 width test images:All detection is correct for 40 defective images, Only have 1 width image in 60 width zero defect images by flase drop, be that a small amount of spot on cell piece surface is erroneously interpreted as the reason for flase drop (surface blot is also considered as defect to defect by some producers for requiring strict, and by this standard, detection accuracy of the invention is 100%).Such flase drop can receive for producer, because for producer, find out all sun for including defect Energy cell piece is mostly important, and a small amount of zero defect cell piece can be received by misjudgement.
The testing result statistics of the width test image of table 1 100
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all essences in the present invention God any modification, equivalent substitution and improvements made etc., should be included in the scope of the protection with principle.

Claims (5)

1. the monocrystaline silicon solar cell piece detection method of surface flaw based on grid line detection, it is characterised in that its step is as follows:
One) monocrystaline silicon solar cell piece surface image is pre-processed using image scaling and medium filtering;Two) grid are passed through Main gate line and secondary grid line in monocrystaline silicon solar cell piece surface image are deleted in line detection;Three) using super-pixel segmentation and certainly Adapt to thresholding method and detect defect area in without grating figure picture, obtain initial detecting result figure;Four) image scaling is passed through Initial detecting result figure is post-processed, obtains final testing result figure;
Described detected by grid line deletes main gate line in monocrystaline silicon solar cell piece surface image and the method for secondary grid line is:
1) the gray scale sum of pretreated each row and columns of image I is calculated:
<mrow> <msub> <mi>SH</mi> <mi>x</mi> </msub> <mo>=</mo> <munderover> <mo>&amp;Sigma;</mo> <mrow> <mi>y</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>g</mi> </munderover> <mi>I</mi> <mrow> <mo>(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>)</mo> </mrow> <mo>,</mo> <mi>x</mi> <mo>&amp;Element;</mo> <mo>&amp;lsqb;</mo> <mn>1</mn> <mo>,</mo> <mi>k</mi> <mo>&amp;rsqb;</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>3</mn> <mo>)</mo> </mrow> <mo>,</mo> </mrow>
<mrow> <msub> <mi>SL</mi> <mi>y</mi> </msub> <mo>=</mo> <munderover> <mo>&amp;Sigma;</mo> <mrow> <mi>x</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>k</mi> </munderover> <mi>I</mi> <mrow> <mo>(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>)</mo> </mrow> <mo>,</mo> <mi>y</mi> <mo>&amp;Element;</mo> <mo>&amp;lsqb;</mo> <mn>1</mn> <mo>,</mo> <mi>g</mi> <mo>&amp;rsqb;</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>4</mn> <mo>)</mo> </mrow> <mo>;</mo> </mrow>
Wherein, xth row in I (x, y) representative image I, at y row pixel gray value, SHxRepresent image I xth row all pixels Gray scale and SLyRepresent the gray scale and k, g representative image I line number and columns of image I y row all pixels;
2) position of main gate line and secondary grid line is detected:
<mrow> <mi>Z</mi> <mi>X</mi> <mo>=</mo> <mfenced open = "{" close = ""> <mtable> <mtr> <mtd> <mrow> <mi>Z</mi> <mi>X</mi> <mo>&amp;cup;</mo> <mo>{</mo> <mi>x</mi> <mo>}</mo> <mo>,</mo> </mrow> </mtd> <mtd> <mrow> <msub> <mi>SH</mi> <mi>x</mi> </msub> <mo>&amp;GreaterEqual;</mo> <mfrac> <mn>1</mn> <mi>k</mi> </mfrac> <munderover> <mo>&amp;Sigma;</mo> <mrow> <mi>x</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>k</mi> </munderover> <msub> <mi>SH</mi> <mi>x</mi> </msub> <mo>,</mo> <mi>x</mi> <mo>&amp;Element;</mo> <mo>&amp;lsqb;</mo> <mn>1</mn> <mo>,</mo> <mi>k</mi> <mo>&amp;rsqb;</mo> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mi>Z</mi> <mi>X</mi> <mo>,</mo> </mrow> </mtd> <mtd> <mrow> <mi>o</mi> <mi>t</mi> <mi>h</mi> <mi>e</mi> <mi>r</mi> <mi>w</mi> <mi>i</mi> <mi>s</mi> <mi>e</mi> </mrow> </mtd> </mtr> </mtable> </mfenced> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>5</mn> <mo>)</mo> </mrow> <mo>,</mo> </mrow>
<mrow> <mi>Z</mi> <mi>Y</mi> <mo>=</mo> <mfenced open = "{" close = ""> <mtable> <mtr> <mtd> <mrow> <mi>Z</mi> <mi>Y</mi> <mo>&amp;cup;</mo> <mo>{</mo> <mi>y</mi> <mo>}</mo> <mo>,</mo> </mrow> </mtd> <mtd> <mrow> <msub> <mi>SL</mi> <mi>y</mi> </msub> <mo>&amp;GreaterEqual;</mo> <mfrac> <mn>1</mn> <mi>g</mi> </mfrac> <munderover> <mo>&amp;Sigma;</mo> <mrow> <mi>y</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>g</mi> </munderover> <msub> <mi>SL</mi> <mi>y</mi> </msub> <mo>,</mo> <mi>y</mi> <mo>&amp;Element;</mo> <mo>&amp;lsqb;</mo> <mn>1</mn> <mo>,</mo> <mi>g</mi> <mo>&amp;rsqb;</mo> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mi>Z</mi> <mi>Y</mi> <mo>,</mo> </mrow> </mtd> <mtd> <mrow> <mi>o</mi> <mi>t</mi> <mi>h</mi> <mi>e</mi> <mi>r</mi> <mi>w</mi> <mi>i</mi> <mi>s</mi> <mi>e</mi> </mrow> </mtd> </mtr> </mtable> </mfenced> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>6</mn> <mo>)</mo> </mrow> <mo>;</mo> </mrow>
Wherein, ZX represents the row coordinate set where main grid line position in image I, and ZY is represented in image I where secondary grid line position Row coordinate set;If the gray scale and SH of xth rowxMore than or equal to the average value of all row gray scale sumsThen xth row It is the row that main gate line is sitting in, now, the coordinate " x " of this line is brought into set ZX;If the gray scale and SL of y rowyGreatly In the average value equal to all row gray scale sumsThen y row are the row that secondary grid line is sitting in, now, by the seat of this row Mark " y " is brought into set ZY;
3) main gate line and secondary grid line are deleted:
According to the instruction of row coordinate in row coordinate set ZX, corresponding row is deleted from image I, realizes and deletes main gate line;Root According to the instruction of row coordinate in row coordinate set ZY, corresponding row are deleted from image I, realizes and deletes secondary grid line;Main gate line and Image tagged after secondary grid line is deleted is image I', and its size is p × q, and p, q are positive integers, and p < k, q < g.
2. the monocrystaline silicon solar cell piece detection method of surface flaw according to claim 1 based on grid line detection, its It is characterised by, the pretreatment includes greyscale image transitions, image scaling and median filter method:
1) greyscale image transitions:The monocrystaline silicon solar cell piece surface image collected is converted into gray level image, obtained Gray level image is I1
2) image scaling:By the gray level image I that size is m × n1Equal proportion scaling is carried out, obtains the scaling figure that resolution ratio is k × g As I2;Wherein, scaling is r ∈ (0,1), k=round (m × r), and g=round (n × r), round () represent four houses Five enter computing, and m, n, k, g are nonnegative integers, and m, n represent gray level image I1Line number and columns, k, g represent zoomed image I2's Line number and columns;
3) image noise reduction:Using median filter method to zoomed image I2Noise reduction is carried out, the pulse being had a great influence to detection is removed and makes an uproar Sound, the image tagged after noise reduction is I, and resolution ratio is k × g.
3. the monocrystaline silicon solar cell piece detection method of surface flaw according to claim 2 based on grid line detection, its It is characterised by, the median filter method is to zoomed image I2Carrying out the method for noise reduction is:Define the pixel that coordinate is (x, y) Neighborhood be:
Nx,y(R)=(i, j) | | i-x |≤R, | j-y |≤R } (1)
Wherein, R is positive integer, represents the radius of neighborhood, and (i, j) represents the coordinate of pixel in neighborhood, Nx,y(R) represent with picture Centered on vegetarian refreshments (x, y), radius be R neighborhood in all pixels point coordinate set;
Medium filtering is carried out to pixel (x, y), its result is:
I (x, y)=Median { I2(i,j),(i,j)∈Nx,y(R)} (2)
Wherein, I (x, y) be pixel (x, y) medium filtering after gray value, I2(i, j) is zoomed image I2Middle coordinate for (i, J) gray value of pixel, Median { } are to take median operation;
The R=1 of formula (2);Utilize formula (2) traversal zoomed image I2All pixels point can obtain image I.
4. the monocrystaline silicon solar cell piece detection method of surface flaw according to claim 1 based on grid line detection, its It is characterised by, detects defect area in the no grating figure picture, the method for obtaining initial detecting result figure is:
1) super-pixel segmentation
Image segmentation is carried out to the image I' for deleting main gate line and secondary grid line using SLIC super-pixel algorithm, the region mark after segmentation It is designated as:F={ F1,F2,...,FT, wherein, T represents the quantity of cut zone, and each cut zone is from the upper left corner of image to bottom right Angle is sorted successively, Fc, c ∈ [1, T] represent all pixels point that c-th of cut zone includes;
2) adaptive thresholding
A. each cut zone F is calculatedcAverage gray value be:
<mrow> <mi>M</mi> <mrow> <mo>(</mo> <msub> <mi>F</mi> <mi>c</mi> </msub> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mn>1</mn> <mrow> <mo>|</mo> <msub> <mi>F</mi> <mi>c</mi> </msub> <mo>|</mo> </mrow> </mfrac> <munder> <mo>&amp;Sigma;</mo> <mrow> <mo>(</mo> <mi>i</mi> <mo>,</mo> <mi>j</mi> <mo>)</mo> <mo>&amp;Element;</mo> <msub> <mi>F</mi> <mi>c</mi> </msub> </mrow> </munder> <msup> <mi>I</mi> <mo>&amp;prime;</mo> </msup> <mrow> <mo>(</mo> <mi>i</mi> <mo>,</mo> <mi>j</mi> <mo>)</mo> </mrow> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>7</mn> <mo>)</mo> </mrow> </mrow>
Wherein, I'(i, j) the i-th row in representative image I', at j row pixel gray value, M (Fc), c ∈ [1, T] represent cut section Domain FcAverage gray value, | Fc| represent cut zone FcThe number of middle pixel;
B. defect area is determined by threshold decision:
<mrow> <mi>D</mi> <mrow> <mo>(</mo> <msub> <mi>F</mi> <mi>c</mi> </msub> <mo>)</mo> </mrow> <mo>=</mo> <mfenced open = "{" close = ""> <mtable> <mtr> <mtd> <mrow> <mn>0</mn> <mo>,</mo> </mrow> </mtd> <mtd> <mrow> <mi>M</mi> <mrow> <mo>(</mo> <msub> <mi>F</mi> <mi>c</mi> </msub> <mo>)</mo> </mrow> <mo>&gt;</mo> <mfrac> <mn>1</mn> <mi>T</mi> </mfrac> <munderover> <mo>&amp;Sigma;</mo> <mrow> <mi>c</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>T</mi> </munderover> <mi>M</mi> <mrow> <mo>(</mo> <msub> <mi>F</mi> <mi>c</mi> </msub> <mo>)</mo> </mrow> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mn>1</mn> <mo>,</mo> </mrow> </mtd> <mtd> <mrow> <mi>o</mi> <mi>t</mi> <mi>h</mi> <mi>e</mi> <mi>r</mi> <mi>w</mi> <mi>i</mi> <mi>s</mi> <mi>e</mi> </mrow> </mtd> </mtr> </mtable> </mfenced> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>8</mn> <mo>)</mo> </mrow> </mrow>
D(Fc), c ∈ [1, T] represent cut zone FcTesting result, represent cut zone F if 0cBelong to defect area, Otherwise cut zone FcBelong to non-defective region;
After obtaining the testing result of all cut zone, initial detecting result figure D is obtained, size is p × q.
5. the monocrystaline silicon solar cell piece detection method of surface flaw according to claim 1 based on grid line detection, its It is characterised by, the method for the post processing is:
Image scaling:Equal proportion image scale operation is performed in pretreatment stage, scaling is r ∈ (0,1), now will be initial Testing result figure D carries out the inverse operation of equal proportion image scaling according to former ratio r, obtains the big of final detection result image M, M Small is h × l, h=round (p/r), l=round (q/r);M is bianry image, and the gray value of defect area is 0, non-defective area The gray value in domain is 1.
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