Displaying objects found with bwconncomp

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Ivan Aguilar
Ivan Aguilar on 11 Oct 2021
Answered: DGM on 11 Oct 2021
I have found the amount of objects in my binary image, but I am not sure how to display those objects.
  2 Comments
Walter Roberson
Walter Roberson on 11 Oct 2021
If you have (for example) 73 connected components, do you want 73 figures, each of which shows the full-sized image but with everything black except for the connected component which is in its proper relative position ?
Ivan Aguilar
Ivan Aguilar on 11 Oct 2021
Not all components, just two, the two that have the maximum and minimum areas.

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Answers (1)

DGM
DGM on 11 Oct 2021
I never really use bwconncomp, but I guess you could do something like this.
% create test image
A = imread('coins.png') > 80;
A = bwareaopen(A,100);
imshow(A)
% find min/max blob areas
C = bwconncomp(A);
area = cell2mat(cellfun(@numel,C.PixelIdxList,'uniform',false));
[~,mnidx] = min(area);
[~,mxidx] = max(area);
% construct the two images
smallblob = false(size(A));
smallblob(C.PixelIdxList{mnidx}) = true;
largeblob = false(size(A));
largeblob(C.PixelIdxList{mxidx}) = true;
clf; imshow(smallblob)
clf; imshow(largeblob)
If you want a close-cropped image of the blob itself, you can use the "image" property from regionprops()

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