pic=imread('group2.jpg', 'JPG');

gpic = sum(pic,3);   %sum RGB

%normalise
gpic=img_norm(gpic);

%a template face
t = gpic(75:129, 1195:1234);
t=img_norm(t);

res = zeros(size(gpic));

for row=1:(size(gpic,1)-size(t,1)-2)
  disp(row)
  for col=1:(size(gpic,2)-size(t,2)-2)
    cand = gpic(row:row+size(t,1)-1, col:col+size(t,2)-1);
    
    cand=img_norm(cand);
    %project onto template
    
    res(row,col) = t(:)'*cand(:);
    
  end
end