MATLAB: How to calculate the mean of an image

image processingmean

How to calculate the mean of an image? Does the code mean2(img) give the right result?

To calculate the mean of all pixels in the image, without regard to what color channel they came from (if it's a color image), you do

meanIntensity = mean(img(:));

What you did will not do it, as I'm sure you found out.

same

For example, if you want sliding means and stds in all 3x3 neighborhoods

slidingmean=conv2(A,ones(3)/9,'same');
slidingstd=stdfilt(A);

or if you don't have the Image Processing Toolbox

 slidingstd=sqrt( conv2(A.^2,ones(3)/9,'same') - slidingmean.^2 );