How to calculate large noise signal from an image

I want to calculate weighting factor for image processing by formula given below:

Where Lm,n is larger signal and Li,j is larger noise signal. My question ius that how I can caclulate larger signal (Li,j) for noise in matlab.

[Image Analyst]

What are Lmn and Lij larger than?

Are you supposed to get the Lij noise image from the Lmn "sample" image? Do you know anything about the signal or the noise? What is sigma(i, j)? Is it just simply std(double(Lij(:)))? And what is the value of beta?

[Mandeep Kaur]

Hi

Thank you for your quick reply. L defines here large signals: I think it means maximum signal. Yes, pixel (i,j) determining noise and pixel (m,n) determine the signal. Yes, I know how to calculate signal to noise ratio (by mean and standard deviation). sigma is noise, I will calculate it by using standard deviation of Lij, as you defined above. beta is a parameter which is controlling signal to noise ratio. We can control it according to our requirements. I am taking here 1.5. I am just confused how to calculate larger signal and larger noise. if I am right larger signal can be calculated by max(double(I(:)))? but I do not have any idea about large noise.

Thank you