# additive Gaussian noise with different SNR

I am reading a paper. It says like this:

"*For experiments conducted on
noisy images, each texture image was corrupted by additive
Gaussian noise with zero mean and standard deviation that was
determined according to the corresponding Signal-to-Noise Ratios
(SNR) value.*"

And then, they show the classification rate (%) on UIUC database with additive gaussian nosie of different Signal-To-Noise Rations (SNR):(SNR=100 SNR=30 SNR=15 SNR=10 SNR=5)

So I want to do the same....

Is GaussianBlur my function? How do I determine the SNR?