Could someone please explain me this code(crack detection)?

I = (imread('original.png'));
% 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)

[Walter Roberson]

No.

See https://www.mathworks.com/matlabcentral/answers/365964-can-someone-please-explain-this-code-to-me#answer_290114

Answer 1

[Image Analyst]

Looks like some sort of edge detection code where it finds edges and then removes ones smaller than 65 pixels.