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Discussion Groups | Matlab DSP | how to find centroid of an object in an image???


Technical discussion about Matlab and issues related to Digital Signal Processing.

  

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how to find centroid of an object in an image??? - DXT_77 - May 23 4:58:00 2003

hi every body,

i have an image which has a picture of a ball in it
and i want to find the centroid of that ball
so when i display it on a 2dplot i know the exact pixel coord
and then i can find it's real coord.
the problem is i don't know how how to find or the formula for
centroid of an object?

thanks for any help,

Lucas








Re: how to find centroid of an object in an image??? - Zahra A Shah - May 23 15:00:00 2003

Are you working with binary images. If so, then the following code will help you find the centroid of the image:
% read the image
i = imread('ball.bmp');
% convert to double
i = double(i);
% invert the image so that we can label the image
% the invert function is not given in the DIP toolbox
% i am attaching it with this email
i = invert(i);
% apply 8-connected algo
[labels,count] = bwlabel(i,8);
% calculate features. For more type help imfeature
features = imfeature(labels,'Centroid');
i = 1;
while i <= count
        % display centroid of all the subimages in the image
       disp(features.Centroid);
       i = i + 1;
end
 
Hope this helps.
Good luck


Zahra Atiq Shah



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