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Re: fitting mixed gaussians [message #44131 is a reply to message #44130]

Wed, 18 May 2005 13:35

jcami
Messages: 4
Registered: May 2005

Junior Member

> Yes I looked at these - the trouble is that I want to perform this on

> literally thousands of images (each image has one object in it).
Manual
> seeding is not practical. I think what I am after is described
here...
>
> http://tinyurl.com/9horr
>
> I have started to translate the MatLab code to IDL - but it is
clearly
> over my head.

I would start by writing a function that creates multiple Gaussians.
Something like

FUNCTION multi_gauss, X, P

; P contains a set of 3 parameters per Gaussian, plus an offset and a
slope
; for the linear part of the model.

n_gauss = (n_elements(P)-2)/3
profile = dblarr(n_elements(X))
for loop=0,n_gauss-1 do begin
this_P = P[loop*3:loop*3+2]
this_u = (X-this_P[1])/this_P[2]
profile = profile + this_P[0] * exp(-5d-1 * this_u^2)
endfor
profile = profile + P[n_g * 3]
profile = profile + P[n_g * 3 + 1] * X

return, profile

END

You can feed this sort of function to mpfitfun; in your peak fitting
routine
you can then start with a single Gaussian, subtract the fit from the
data and look for a second Gaussian (again using something like
mpfitpeak); if you find a second Gaussian, you use the parameters for
both Gaussians as initial estimates to the multi_gauss routine and
mpfitfun should do the rest.

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[Message index]

		Re: fitting mixed gaussians By: btt on Fri, 20 May 2005 07:10
		Re: fitting mixed gaussians By: Craig Markwardt on Wed, 18 May 2005 17:37
		Re: fitting mixed gaussians By: jcami on Wed, 18 May 2005 13:35
		Re: fitting mixed gaussians By: btt on Wed, 18 May 2005 07:54
		Re: fitting mixed gaussians By: Rob Dimeo on Tue, 17 May 2005 12:55
		Re: fitting mixed gaussians By: David Fanning on Tue, 17 May 2005 11:32

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