Find branches in a skeleton?

Question

Ronan 2015-9-15

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/243138-find-branches-in-a-skeleton

评论： karishma singh 2017-8-8

When you make a skeleton from a binary image you can extract branch points. However I m trying to find out which branch points are connected to which. I can find the index of the branch points. So I have a skeleton with labeled branch points and I can physically view the nodes that are connected to one another but I cannot seem to generate these connections in code? eg branch point 3 is connected to branch point 5.

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Ronan 2015-9-15

编辑：Walter Roberson 2015-9-15

在 MATLAB Online 中打开

pic = imread('boo.bmp');
pic = rgb2gray(pic);
I = im2bw(pic);
BW3_skel = bwmorph(I,'skel',inf);
figure(1);
imshow(BW3_skel);
BW3_branchpoints = bwmorph(BW3_skel, 'branchpoints');
the_r = pic;
the_g = pic;
the_b = pic;
the_r(BW3_skel) = 255;
the_g(BW3_skel) = 0;
the_b(BW3_skel) = 255;
the_out = cat(3,the_r,the_g,the_b);
figure(2)
imshow(the_out);
[node_x,node_y] = find(BW3_branchpoints == 1);
hold on
%imshow(myImage);
nodes = [(1:length_node_x); the_nodes]';
plot(nodes(:,2), nodes(:,3),'b.');
length_node_x = length(node_x);
the_nodes = zeros(2,length_node_x);
the_nodes(1,1:end) = node_y(1:end);
the_nodes(2,1:end) = node_x(1:end);
for s = 1:length_node_x
     text(nodes(s,2),nodes(s,3),[' ' num2str(s)], 'Color', 'r'); 
    %plot(nodes(segments(s,2:3)',2),nodes(segments(s,2:3)',3),'c');
end
disp(nodes);

The out put of the nodes is in the format [index, x, y].

I have also attached the two outputs from the code that displays the skeleton image with the labeled nodes.

Walter Roberson 2017-8-6

karishma singh: which code was it that you ran? None of the code that is posted in this Question calls Preprocess or defines a variable named the_out ?

karishma singh 2017-8-8

Preprocess.m is just my file name. I ran the code posted by Ronan using my skeleton image.

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Answer 1

Image Analyst 2015-9-15

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/243138-find-branches-in-a-skeleton#answer_192478

I think you'll need to get an image of just the branch points. Then an image of just the branches with the branchpoints removed. Then pick two branchpoints to test and make an image with just those two. Then put in each branch one at a time and call bwdistgeodesic() to see if they're connected by that branch.

Steve's blog may help: http://blogs.mathworks.com/steve/2011/11/01/exploring-shortest-paths-part-1/

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Ronan 2015-9-15

I was hoping to do it without the bwdistgeodesic function because my version of matlab doesn't have that function. I was thinking of trying to traverse the skeleton path and while traversing keep checking if the skeleton pixel is one of the nodes. It would probably involve a mask for checking if adjacent pixels are the skeleton however this solution is tricky and maybe computationally expensive. also it seems like reinventing the wheel because thats how some of the bwmorph operations work. Do you know is there an open source or alternative version to bwdistgeodesic?

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