Find CDF in image

Hello, I have an image and i want use CDF function for find CDF 0.5. How can use CDF function in matlab? I read help but i can't understand well. Thanks

I = imread('cameraman.tif'); 
%%FIND CDF 0.5 for this image.

Answer 1

[Image Analyst]

Perhaps something like this to find the cumulative distribution function (integral of the histogram):

counts = histcounts(grayImage);
cdf = cumsum(counts)/sum(counts);

[Image Analyst]

Dani's "Answer" moved here because it's a comment to me rather than an Answer to her original question:

Thanks, But CDF 0.5 is point which half pixel is left and half pixel should right. CDF 0.5 is one point (is pixel)

[Image Analyst]

Not sure what that means exactly, but if you want the median value you can use

medianValue = median(I(:));

You should get close the the same value if you use find on cdf

medianValue = find(cdf >= 0.5, 1, 'first');