Got it. Not the most elegant solution, but it works. Thanks for the tips!
size_image = size(image)
filt_image = zeros(size_image)
for j = 1:size_image(2)
[rows, columns] = find((image(:,j)) > 0);
row_index = round(mean(rows));
filt_image(:,j) = image(:,j);
filt_image(:,j) = 0;
filt_image(row_index,j) = 1;
end