Crack Detection

Question

Dio Donaika on 13 Jun 2012

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https://uk.mathworks.com/matlabcentral/answers/41089-crack-detection

Commented: Walter Roberson on 7 Jul 2016

I have problem for detection for surface ceramics image, how i can detect crack surface , pls give me some advice. this my code for detect crack surface

function [img1_array, img2_array,img3_array, img4_array,Zme]= DefectScan(input_path,input_path2);
% clear all;
% close all;
I = imread(input_path2);
J = imread(input_path);
I = rgb2gray(I);
J = rgb2gray(J);
% f=figure,imshow(I);
% g=figure,imshow(J);
hy = fspecial('sobel');
hx = hy';
Iy = imfilter(double(I), hy, 'replicate');
Ix = imfilter(double(I), hx, 'replicate');
ey = fspecial('sobel');
fx = ey';
Jy = imfilter(double(J), ey, 'replicate');
Jx = imfilter(double(J), fx, 'replicate');
gradmag = sqrt(Ix.^2 + Iy.^2);
gradmag2 = sqrt(Jx.^2 + Jy.^2);
K=figure,imshow(gradmag,[]);
L=figure,imshow(gradmag2,[]);
set(K, 'visible','off');
set(L, 'visible','off');
filename  = 'temp_file.jpg'
filename2 = 'temp_file2.jpg'
saveas(K, filename)
saveas(L, filename2)
i1 = imread(filename)
i2 = imread(filename2)
delete(filename)
delete(filename2)
[x, y, rgb] = ind2sub([size(i1,1) size(i1,2) size(i1,3)], find(i1 ~= 255));
A = i1(min(x):max(x)-1,min(y):max(y)-1,:);
[x, y, rgb] = ind2sub([size(i2,1) size(i2,2) size(i2,3)], find(i2 ~= 255));
B = i2(min(x):max(x)-1,min(y):max(y)-1,:);
A = rgb2gray(A)
B = rgb2gray(B)
I = edge(A,'sobel')
J = edge(B,'sobel')

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Walter Roberson on 16 Jun 2012

"We're sorry but you do not have access to this page"

Dio Donaika on 16 Jun 2012

im sory this question not for u i mean for all, i really sory

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Answer 1

Dio Donaika on 16 Jun 2012

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https://uk.mathworks.com/matlabcentral/answers/41089-crack-detection#answer_50902

this link picture : http://i1164.photobucket.com/albums/q570/diodonaika/1.jpg my code just detect pinhole like this http://i1164.photobucket.com/albums/q570/diodonaika/0674.jpg i want to detect crack from tile, need for help ...

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Walter Roberson on 16 Jun 2012

I see some slanted lines that are fairly straight, but those look to me like scratches rather than cracks.

I see a number of areas that are raised, but possibly the places that appear lower are instead filled with something that is optically transparent and the tile overall has a flat surface.

Could you perhaps post the images 1 and 2 again, with cracks pointed out with marks?

Dio Donaika on 22 Jul 2012

Open in MATLAB Online

Im soory to late, because i just have the data from my senior this image crack http://i1164.photobucket.com/albums/q570/diodonaika/diodo.jpg and i have done detect the crack http://i1164.photobucket.com/albums/q570/diodonaika/diodo2.jpg

this my code I = imread('diodo.jpg');

I = rgb2gray(I);
% f=figure,imshow(I);
% g=figure,imshow(J);
hy = fspecial('sobel');
hx = hy';
Iy = imfilter(double(I), hy, 'replicate');
Ix = imfilter(double(I), hx, 'replicate');
gradmag = sqrt(Ix.^2 + Iy.^2);
K=figure,imshow(gradmag,[]);
set(K, 'visible','on');
filename  = 'temp_file.jpg'
saveas(K, filename)
i1 = imread(filename)
delete(filename)
[x, y, rgb] = ind2sub([size(i1,1) size(i1,2) size(i1,3)], find(i1 ~= 255));
A = i1(min(x):max(x)-1,min(y):max(y)-1,:);
A = rgb2gray(A)
I = edge(A,'sobel')
%934 742
I = imcrop(I,[10 7 914 728]);
I = imresize(I, [2000 2500])
f=figure,imshow(I);
set(f, 'visible','on');
imwrite(I, filename)
bw = imread(filename)
delete(filename)
bw = im2bw(bw, graythresh(bw))
bw = bwareaopen(bw,65);
set(f, 'visible','on');
f, imshow(bw)

What do i do next to calculate crack in centimeter ? please help me

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Answer 2

Image Analyst on 22 Jul 2012

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"What do i do next to calculate crack in centimeter ?" Well, what is the size of your field of view in cm? Let's say it's 30 cm and your image width is 1000 pixels. Then your calibration factor is 30/1000 cm per linear pixel, or 30^2/1000^2 cm^2 per pixel area. So just multiply your pixel lengths or areas by those factors to get the results in cm or cm^2.

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Dio Donaika on 27 Aug 2012

is there another way to detect defects in the image that I have. My method was rejected by the faculty, can you help me what I should do in order to identify the image

Dio Donaika on 27 Aug 2012

Open in MATLAB Online

for k = 1:length(B)
      boundary = B{k};
      plot(boundary(:,2), boundary(:,1), 'black', 'LineWidth', 1)
      end
      stats = regionprops(L,'Perimeter', 'MajorAxisLength','EquivDiameter', 'Area');

I have followed the commands you give, but my college teacher does not allow to use it because it had previously been used by senior. please help me.im confused to ask to whom

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Answer 3

Sarhat on 29 Nov 2012

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https://uk.mathworks.com/matlabcentral/answers/41089-crack-detection#answer_66941

Hello

I have used your algorithm for Crack detection in the pavement but doesn't helped. I have made an algorithm for detection of crack based on sobel edge detection. the problem, there are lots of false positive which I want to remove and only remain the edges belong to cracks.

Regards

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Image Analyst on 29 Nov 2012

I don't see a question. If you have a question on MATLAB programming, you can start your own thread. But we give a lot more help on MATLAB programming and some, but not so much, on algorithm development.

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