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Re: Mask ? [message #6967 is a reply to message #6853] Sat, 07 September 1996 00:00 Go to previous message
pford is currently offline  pford
Messages: 33
Registered: September 1996
Member
In article <4vrkm3$pt8@news.u-bordeaux.fr>, Mario Noyon <mnoyon> wrote:

> I want to mask the background of an image to have only the interesting signal.
> The procedure of ERODE doesn't seem to work.
>
> Does someone have an idea?
>
> Thanks in advance.
> --
> NOYON Mario
> Computer Science engineer
> University of Bordeaux 2
> mnoyon@jmc-luni.u-bordeaux2.fr

That depends on your backgound and signal. If you have a uniform
background of value 50 or less then you could do :

X = (X GT 50) * X;


Where X is an integer or byte array. Use 50.0 for a fltarr.

You could also filter the data using FFT or Wavelets to remove unwanted signal.
You could take the Single Value Decomposition (SVDC function) to get the
eigenvalues and eigenvectors and drop the signal that contributes only a
small percentage to the total.

Patrick Ford, MD
Department of Radiology
Baylor College of Medicine
Houston, Texas USA
pford@bcm.tmc.edu
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