How to calculate Signal to noise ratio for a CT scan image?

Answer 1

[Rahul]

Hi @Krishna Pavan,

In order to obtain the Signal to Noise ratio (SNR) of the given CT scan image, consider using the following formula for SNR

• SNR = 10*log10(signal/noise)
• Here 'signal' can be considered as the mean of the pixel values of the CT Scan image.
• Here 'noise' can be considered as the standard deviation of the pixel values of the CT Scan image.

Here is an example:

% Considering 'img' to be the variable containing CT scan image data
signal = mean(double(img(:)));
noise = std(double(img(:)));

SNR = 10*log10(signal/noise);

The following MATLAB Answers also mentions similar approaches:

https://www.mathworks.com/matlabcentral/answers/57152-snr-of-an-image

https://www.mathworks.com/matlabcentral/answers/55649-how-to-calculate-actual-snr-of-image-in-matlab

The following MathWorks documentations can be referred to know more:

'mean': https://www-test1.mathworks.com/help/releases/R2018b/matlab/ref/mean.html

'std': https://www-test1.mathworks.com/help/releases/R2018b/matlab/ref/std.html

Thanks.