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Finding X and Y coordinates of a single white blob on a black background

Asked by David Bridges

David Bridges (view profile)

on 18 Sep 2013

I have a series of images which I need to find the x,y coordinates for a single white blob on black background. I would like coordinates to be taken from the center of the image. Thank you.

0 Comments

David Bridges

David Bridges (view profile)

1 Answer

Answer by Image Analyst

Image Analyst (view profile)

on 18 Sep 2013
Accepted answer

This is done by my BlobsDemo program. http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862.

The blobs are the coins from the standard MATLAB demo image. It finds the centroids of all of them. You just need to subtract the number of rows and columns divided by 2 to get the coordinates referenced to a new coordinate system where the origin is in the middle of the picture.

6 Comments

David Bridges

David Bridges (view profile)

on 23 Sep 2013

Thanks, I have tried that but I cannot make it fit with your existing code. If you wouldn't mind a quick look, I have attached something that is looping already, but it only prints the centroids of the last jpg file in the folder. Files are virus-checked etc. Much appreciated!

Image Analyst

Image Analyst (view profile)

on 23 Sep 2013

You have a loop that says

for j=1      

so of course it does only 1 image.

David Bridges

David Bridges (view profile)

on 24 Sep 2013

Finally figured it out, thanks for your help

Image Analyst

Image Analyst (view profile)

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