How to get the probability of the intensity level of an image ?

I have a grey scale image that I want to get the probability of every intensity level, I know it mathematically but i have no idea how to do it on Matlab please help !!1

Answer 1

[Image Analyst]

[pixelCounts, grayLevels] = imhist(grayImage);

[Sahar Magdy]

Won't that get me the number of pixels in each grey level ?

[Image Analyst]

Yes, of course. And how do you think you'd get the probability? Divide by something? Like what if you divided by the number of pixels in the image? What is the formula that you "know mathematically" if it's not what I described?