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Re: particle detection - a way to speed up things? [message #57114 is a reply to message #57067]

Mon, 03 December 2007 08:30

Dan Larson
Messages: 21
Registered: March 2002

Junior Member

Hi,

Depending on the types of blobs you are detecting, FFT filtering can
often work much faster for the initial segmentation. My approach for
particle detection:
1. spatial bandpass to identify the regions of interest.
2. cut out the regions of interest to pass to the fitting routine (as
David suggested).
3. find the center using the algorithm of choice.

This last step can be any number of things, but if you choose a
centroid approach, these lines work well for me, although I think they
are similar to what you have:

a=size(pic)
x_dim = a[1]
y_dim = a[2]
array=lindgen(x_dim, y_dim)
xarr=array mod x_dim
yarr=array/x_dim
sum=double(total(pic))
xcenter=total(xarr*pic)/sum
ycenter=total(yarr*pic)/sum
return, [xcenter, ycenter, sum]
end

For fourier filtering, I particulary like a routine from Crocker and
Grier: www.physics.emory.edu/~weeks/idl/kit/bpass.pro

If you are interested in detecting and fitting diffraction-limited
spots in a fluorescence microscope, I have software which is
specifically designed for that purpose. I could send that to you
directly if you want to try it out.

best,
dan

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[Message index]

		particle detection - a way to speed up things? By: Ingo von Borstel on Wed, 28 November 2007 05:40
		Re: particle detection - a way to speed up things? By: dcleon@gmail.com on Fri, 30 November 2007 08:02
		Re: particle detection - a way to speed up things? By: Dan Larson on Mon, 03 December 2007 08:30
		Re: particle detection - a way to speed up things? By: Vince Hradil on Fri, 30 November 2007 06:02

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