How to Determine Column(s) with Most Non-zero values in a matrix?

I have a matrix filled with zeros and ones (a black and white image). Most colums are filled with zeros and I want to find which columns has the most ones in them for position determining. How can I do this efficiently?

Answer 1

[Azzi Abdelmalek]

A=randi([0 1],8)
[~,idx]=max(sum(A))