Flexslider - add/replace div class outside of slider loop for each slide

Flexslider - add/replace div class outside of slider loop for each slide

I have 'header' div container outside of slider.
And I have slider images with 'white' or 'black' classes. 
Is it possible to implement the following: After slide loading 'header' container assigned image class (black/white) on the fly.
I have flexslider as background slider under header. When slide image dark header is displayed with light styles. Is it possible?

Sorry for my english. Thanks

  2. <div class="header"></div>
  3.     
  4. <script type="text/javascript" charset="utf-8">
  5.   $(document).ready(function() {
  6.     $('.flexslider').flexslider();
  7.   });
  8. </script>
  9.     
  10. <div class="flexslider">  
  11.      <ul class="slides"> 
  12. <li><img src="someimage.jpg" class="white"/></li>
  13.         <li><img src="someimage.jpg" class="black"/></li>
  14.         <li><img src="someimage.jpg" class="white"/></li>
  15.         <li><img src="someimage.jpg" class="white"/></li>
  16.      </ul>
  17. </div>