Re: Geometric center of a group of particles?

Posted by HoweLab on Oct 10, 2009; 2:12pm
URL: http://imagej.273.s1.nabble.com/Geometric-center-of-a-group-of-particles-tp3690868p3690871.html

That worked *perfectly*! Thanks very, very much Winnok.

-Alan

Winnok H. De Vos wrote

Hi Alan

You could determine the maxima as a selection using find maxima (under  
process>binary) either on a binary image (if you already have a way of  
segmenting all the blobs) or on your original image (with a certain  
noise tolerance) and subsequently fit the convex hull (under  
edit>selection) after which you allow the analyze particles command to  
find the centroid. This is only an aproximating way but does not take  
the internal distribution nor size or intensity of the blobs into  
account, which seems to suit your needs.  Maybe this already helps.
Kind regards,

Winnok


On 09 Oct 2009, at 22:55, HoweLab wrote:

> Hi.
>
> We routinely generate images comprising 'roughly' circular groups of  
> small,
> circular or ellipsoid particles or blobs. There are typically  
> 5000-10000 per
> group. Is there an easy (or easier) way to determine the geometric  
> center of
> such a group - in other words, a way to get an X,Y coordinate that
> represents the center of the group? The blobs are generally similar  
> in size,
> but can sometimes cluster or clump together. These clumps should not  
> 'pull'
> the center position towards themselves - i.e. we're looking for  
> geometric
> center, not center of mass (I apologize if I'm not using those terms
> correctly). Thanks, in advance, for your advice.
> --
> View this message in context: http://n2.nabble.com/Geometric-center-of-a-group-of-particles-tp3797231p3797231.html
> Sent from the ImageJ mailing list archive at Nabble.com.

___________________________

Winnok H. De Vos, PhD

Bio-imaging and Cytometry Unit
Dept. Molecular Biotechnology
University of Ghent
Coupure Links 653
9000 Ghent, Belgium

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