How to find coordinates of two corner points in an image without using ginput?
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Ivan Shorokhov
on 7 Dec 2014
Edited: Ivan Shorokhov
on 21 Jan 2015
I have two corner points (I marked them in red so you can see it) in black and white image. I want to find coordinates of the points automatically without using 'ginput'.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/146353/image.jpeg)
I used the 'bwlabel' and 'regionprops' functions to crop an original image to find my region of interest (ROI).
im = imread('LA_shape1.jpg');
LA = im2bw(im, graythresh(im));
[Clab num] = bwlabel(LA);
props = regionprops(Clab);
LABox = imcrop(LA,[props.BoundingBox]);
figure; imshow(LABox);
Here is the result after cropping:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/146354/image.jpeg)
Is there any one who can kindly help me to find the coordinates of two corner points without using ginput? Thanks so much!
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Accepted Answer
Image Analyst
on 7 Dec 2014
No need to crop, label, call regionprops. Why bother if all you want are the endpoints? Simply use bwmorph()
skelImage = bwmorph(binaryImage, 'skel', inf);
endPoints = bwmorph(skelImage, 'Endpoints');
[rows, columns] = find(endPoints);
3 Comments
Image Analyst
on 7 Dec 2014
It looks like there are actually 2 endpoints per endpoint. That's because when you skeletonize a rectangle, you get s branch going into each corner. Zoom in and you'll see what I mean. I think it would be fine to just average the x and y points to get one point that is halfway in between the two points.
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