$(document).ready(function(){
  
  function preload_images()
  {
    $('.case_study a img').each(function(){
      // Over
      replacement = $(this).attr("src").replace("-bw", "");
      $(this).attr("src", replacement);
      // Out
      replacement = $(this).attr("src").replace(".jpg", "-bw.jpg");
      $(this).attr("src", replacement);
    })
  }
  
  function mouse_over()
  {
    replacement = $(this).attr("src").replace("-bw", "");
    $(this).attr("src", replacement);
  }
  
  function mouse_out()
  {
    replacement = $(this).attr("src").replace(".jpg", "-bw.jpg");
    $(this).attr("src", replacement);
  }
  
  $('.case_study a img').hover( mouse_over, mouse_out );  
  preload_images();
})