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An object with the biggest amount of scope in the Binary image

Asked by Felix

Felix

on 12 Sep 2013
Accepted Answer by Image Analyst

Image Analyst

Hello, I have a binary image with n white objects (not connected). How can I leave only the object with the biggest amount of scope in the picture I can do it by - bwareaopen, but in this way I have to know approximate size of an object. sorry for my english. thnx

0 Comments

Felix

Felix

3 Answers

Answer by Image Analyst

Image Analyst

on 13 Sep 2013
Accepted answer

Try this:

grayImage = imread('coins.png');
subplot(2,2,1);
imshow(grayImage);
binaryImage = grayImage > 100;
binaryImage = imfill(binaryImage, 'holes'); % Fill holes.
[labeledImage, numObjects] = bwlabel(binaryImage);
stats = regionprops(labeledImage,'Area');
allAreas = [stats.Area]
[~, indexOfLargest] = max(allAreas);
largestBlob = ismember(labeledImage, indexOfLargest)>0;
subplot(2,2,2);
imshow(largestBlob);
title('Largest');
keeperIndexes = 1:numObjects;
keeperIndexes(indexOfLargest) = [];
binaryImage2 = ismember(labeledImage, keeperIndexes)>0;
subplot(2,2,3);
imshow(binaryImage2);
title('All Except Largest');

1 Comment

Felix

Felix

on 17 Sep 2013

thank you! it's good!

Image Analyst

Image Analyst

Answer by Adam Filion

Adam Filion

on 12 Sep 2013
Edited by Adam Filion

Adam Filion

on 12 Sep 2013

If you have Image Processing Toolbox you can use the function regionprops. It comes out to something like this, where tm is the binary image.

cc = bwconncomp(tm);
stats = regionprops(cc,'Area');
A = [stats.Area];
[~,biggest] = max(A);
tm(labelmatrix(cc)~=biggest) = 0;

You can watch a recorded presentation that steps through a similar example here:

https://www.mathworks.com/company/events/webinars/wbnr60402.html

2 Comments

Felix

Felix

on 12 Sep 2013

Thanks for the help, it close enough to what I asked, however, it erased all the small arias except the closest ones to the object . can you tall me why is that? sorry i can't upload an image, can i send it to your e-mail?

Image Analyst

Image Analyst

on 13 Sep 2013

Try uploading an image to http://snag.gy or http://tinypic.com.

Adam Filion

Adam Filion

Answer by Sean de Wolski

Sean de Wolski

on 17 Sep 2013

Good timing, I just posted this function a few minutes ago!

SCd:keepMaxObj

0 Comments

Sean de Wolski

Sean de Wolski

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