From help-request at octave dot org Sun Apr 17 14:26:57 2005
Subject: Re: Zerocrossings in an image
From: =?ISO-8859-1?Q?S=F8ren_Hauberg?= <soren at hauberg dot org>
To: etienne at cs dot uky dot edu
CC: help at octave dot org
Date: Sun, 17 Apr 2005 21:25:31 +0200

Thanks, not only for the quick response, but also for the code. It 
appears to be working very well for my needs.
Can I use your code in a gpl'ed script?

/Søren

Etienne Grossmann wrote:
> Hth
> 
> f = 2*kron (randn(4)>0,ones(4))-1
> 
> z0 = f<0;                 ## Negative
> [R,C] = size(f);
> z = zeros(R,C);
> z(1:R-1,:) |= z0(2:R,:);  ## Grow
> z(2:R,:) |= z0(1:R-1,:);
> z(:,1:C-1) |= z0(:,2:C);
> z(:,2:C) |= z0(:,1:C-1);
> 
> z &= !z0                  ## "Positive zero-crossings"?
> 
> 
> 
> On Sun, Apr 17, 2005 at 06:02:02PM +0200, Søren Hauberg wrote:
> # Hi
> # Does anybody here know a simple way to find the zerocrossings in an 
> # image in Octave?
> # I usually do something like this (where f is the image (or 2d function))
> # 
> # zerocrossings = bwmorph(f>=0, "remove");
> # 
> # but then I depend on bwmorph which only is octave-forge (which I don't 
> # have at school).
> # 
> # Any help would be great,
> # \Søren
> # 
> # 
> # 
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> # Octave is freely available under the terms of the GNU GPL.
> # 
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