# Finding the contrast ratio of a grayscale image

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iseinas on 4 Sep 2020
Commented: Image Analyst on 11 Jul 2021
So as the title says, I want to find the contrast ratio of a grayscale image by Michelson contrast definition. I'm thankful for any help! I'm not sure how to do this. Am I supposed to find the max and min value in each columns or row or the whole matrix?
% Michelson contrast definition
% Imax : the largest value in the image's matrix
% Imin : the smallest value in the image's matrix
contrast = (Imax-Imin)(Imax+Imin) Image Analyst on 6 Sep 2020
Do you need loops, like this is a homework question that requires them? If not, just simply do
Imax = max(I(:))
Imin = min(I(:))
contrast = (Imax - Imin) / (Imax + Imin)
Notice that I'm using the correct formula. You are not. They subtract in the numerator, not divide like you have it.
Image Analyst on 11 Jul 2021

royed on 6 Sep 2020
if the question is about just comapring the max and min in the images. You can find it quite simply by using (max(max(image)) and the same for the minimum which would return the pixel with the max and minimum intensity value.