Path: news.mathworks.com!not-for-mail 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) Organization: Continental Automotive Systems Lines: 29 Message-ID: <h2grnd$8og$1@fred.mathworks.com> References: <h2geje$6jt$1@fred.mathworks.com> <1665e067-91c2-4141-a55b-189f8862d9a8@s6g2000vbp.googlegroups.com> Reply-To: "Rami AbouSleiman" <rdabousl@oakland.edu> NNTP-Posting-Host: webapp-05-blr.mathworks.com Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit X-Trace: fred.mathworks.com 1246491181 8976 172.30.248.35 (1 Jul 2009 23:33:01 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Wed, 1 Jul 2009 23:33:01 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 1325461 Xref: news.mathworks.com comp.soft-sys.matlab:552237 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