title: How to change display normalization settings in CImg?
body: <p>I have read this part of the <a href="http://cimg.sourceforge.net/reference/group__cimg__displays.html" rel="nofollow">CImg documentation</a>: </p>
  
  <p>However, it is not clear how to set this normalization levels (it is not a display() function parameter).</p>
  
  <p>Can anybody tell me how to use them? Thank you!</p>