Calculate pixel intensity summation in Horizontal, Vertcal direction and Diagonally in MATLAB: code and output

I = imread('cameraman.tif');

imshow(I);

v = sum(I,1);

v

I = imread('cameraman.tif');

imshow(I);

v = sum(I,2);

v

I = imread('cameraman.tif');

imshow(I);

v = sum(diag(I));

v