SNR between two images in MATLAB

Below is the algorithm for calculating the SNR of two images in MATLAB:

A = imread('Yes_Noise.png');
A = imgaussfilt(A, 2); %Filtered image

ref = imread('Yes_Noise.png'); %Noisy image

test = snr(ref,ref-A)

Is it the algorithm rigth? It's purpose is find out the SNR value between filtered and nosiy image.

[Adam]

The algorithm is presumably in the function named snr so how would we know from what you have posted so far?!

[Franta Cymorek]

First calm down, I have asked politely, so be polite.

Second, as it is obvious, I just want to know if the last line of the algorithm is correct?

[Adam]

is what the help says, assuming snr is the Matlab Signal Processing Toolbox function. So assuming the difference between the smoothed image and the original is considered noise then yes, subtractubing the filtered image from the original will give this.

[Franta Cymorek]

Thanks...