On Fri, Aug 10, 2001 at 03:34:26PM +0200, Tobias Benedikt Hoevekamp wrote:
> Hi there,
> I am wondering, if there is a script around, that would
> automatically analyze particle sizes. Enclosed is an
> image of a typical problem: several (sometimes even
> overlapping) more or less spherical particles are given.
> I am interested in a script that finds the number of
> spheres and their diameters.
> Best regards,

This is more complicated than one'd normally expect from an image
manipulation program, but a possible way to go might be to edge
detect, threshold, dilate a few pixels, erod a few pixels (gets rid 
of some noise), and then use something like a circular Hough
transformto check whether a point is a good estimator of the
centre of the circle (this will also give radius estimators), and
then count them. The first few stages of that could definitely be
done in the gimp, but you'd be on your own for the complicated
part (the Hough transform, which is described in (among many
others) "Image Processing, Analysis and Computer Vision" by
Sonka, Hlavak and Boyle).

But as with all reasonably complicated image processing
(automated counting of objects is complicated, I'm afraid) there
are many approaches. You might try one or more of the image
analysis/processing newsgroups for more help.


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