that actual snr is

one person say me that actual snr is,,,

if noiseImage=noisyImage-originalImage then actual snr=mean(originalImage./abs(noiseImage)) so my question is that "Is snr depends on mean and variance of noiseImage"?

Answer 1

[Image Analyst]

Yes. More noise = lower SNR, and less noise = higher SNR.

[Walter Roberson]

Considering that the mean is being taken, does the variance of noiseImage affect the SNR? I don't see how: I just see how the mean affects the SNR.

[Image Analyst]

Because the absolute value of the noise image is being taken, the std dev affects the mean. You could have a mean of zero in the original noise, but once you take the abs(), now the mean depends on the std dev. So the SNR of an image with noise = 0 +/- 5 gray levels will be higher than the SNR of the same image with a noise of 0 +/- 200 gray levels.

[Walter Roberson]

Good point.