title: Convert image file to float array in Python
body: <p>How can I convert an image to an array of float numbers?
  img = cv2.imread('img.png')</p>
  
  <p>and now convert img to float so I get for
  print(img[0,0]) something like "[ 4.0 2.0 0.0] instead of [4 2 0]</p>
  
  <p>Do you have an idea? Thank you very much!  </p>