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Trying to automatically crop an image into several smaller images based on segmentation

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Teshan Rezel
Teshan Rezel on 17 Feb 2020
Commented: Teshan Rezel on 18 Feb 2020
Hi all,
Apologies in advance, I'm not well versed in Matlab.
I'm trying to crop a segmented image into several smaller pieces that only contain the a segmented piece of the original image. For example, if an image has 3 apples and I'm interested in the apples, I am aiming to cut out each apple into a seperate image. The result I'm hoping for is 3 seperate images of apples, with anything else in the crop blackened (or whitened) out.
Why I'm trying to do this is so I can pass each resultant image into a CNN for analysis, as each segmented piece/cropped image is a type of object that needs to be classified.
Below is an image of mine that I'm trying to process. Any ideas would be useful! Thanks in advance.


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Teshan Rezel
Teshan Rezel on 17 Feb 2020
that seems to work pretty well, thank you! I get the following image after dilating the mesh and using bwlabel(), but I'm uncertain on how to proceed from here to crop the labelled regions. Apologies if this is an obvious question...but is there a way to automate this?

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Accepted Answer

darova on 17 Feb 2020
Something like this
I = imread('image.jpeg');
I1 = im2bw(I);
I2 = imdilate(I1,ones(5)); % imdilate to close contours
I3 = imerode(I2,ones(4)); % restore thickness
[L,n] = bwlabel(I3); % label regions/areas
title('restore thickness of contours')
for i = 2:n
I4 = L==i; % select region
I5 = imfill(I4,'holes'); % fill contour/region
imshow(cat(3,I5*255,I3*255,I3*0)) % display


Teshan Rezel
Teshan Rezel on 17 Feb 2020
I think this is pretty close to what I need to do, so thank you!
Just a couple of questions: instead of filling I5, is there a way to layer it over the original image and then crop it out?
thanks for all your help thus far by the way!
darova on 17 Feb 2020
Sure. Try this:
I4 = L==i; % select region
I5 = imfill(I4,'holes'); % fill contour/region
I6 = I.*repmat(uint8(I4),[1 1 3]);
imshow(I6) % display cropped region

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