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From: "Rami AbouSleiman" <rdabousl@oakland.edu>
Newsgroups: comp.soft-sys.matlab
Subject: Re: SNR and imnosie
Date: Wed, 1 Jul 2009 23:33:01 +0000 (UTC)
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Mr. Image Analyst,
I know what is  SNR and Gaussian noise, 
but can you relate in a function SNR to the variance of the imnoise function thats my question?
Thanks



ImageAnalyst <imageanalyst@mailinator.com> wrote in message <1665e067-91c2-4141-a55b-189f8862d9a8@s6g2000vbp.googlegroups.com>...
> On Jul 1, 3:49?pm, "Rami AbouSleiman" <rdabo...@oakland.edu> wrote:
> > when i use the imnoise function as for example:
> >
> > I=imnoise(input, 'gaussian', 0 , 0.1)
> > mean is always zero but all i vary is the variance.
> > What does that mean as SNR of I?
> >
> > Any help is greatly appreciated.
> > Thanks
> 
> ---------------------------------------------------------------------------------
> Well let's see.  Signal = input, and average noise = std dev = sqrt
> (variance), so isn't the SNR (on average) at (x,y) just input(y, x)/
> sqrt(0.1) ?     Or you can say that the actual noise = (I-input) so
> then SNR(y, x) = input(y, x) / (I(y, x) - input(y,x)).
> 
> No, that can't be it, that's too obvious - you would have figured that
> out - so what aren't you telling us?  If you really simply want to
> know what SNR means (like you said), then you can use a nifty tool
> called Google, where you might find sites like this:
> http://en.wikipedia.org/wiki/Signal-to-noise_ratio