how to find different features of objects

in this binary image there are some objects in x-y coordinate, I want to find the biggest object and its centroid (x,y). how can I do that?

Answer 1

[Image Analyst]

See my Image Segmentation Tutorial: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862 It finds the centroids of a bunch of circles.

Then, see my attached demo that will find the largest or smallest N blobs in a binary image.

[Abo]

thank you very much for your answer, I've used this method before, for selecting the biggest object but I cannot to find centre of that one. you know the biggest object is ellipse not circle.

[Image Analyst]

There are several ways. For example, you can first call my function that returns only the largest blob. Then you can call bwlabel() and regionprops().

%----------------------------------------------------------
% Extract the largest area using our custom function ExtractNLargestBlobs().
biggestBlob = ExtractNLargestBlobs(binaryImage, numberToExtract);
%---------------------------------------------------------
labeledImage = bwlabel(biggestBlob);
measurements = regionprops(labeledImage, 'Centroid');
centroid = measurements(1).Centroid;

I think maybe you looked only at the ExtractNLargestBlobs demo and did not look at the demo in my File Exchange - they are different. I attach both here.