function randomImage()
{ 
  theimages = new Array("images/latest_version/middle_pic1.jpg","images/latest_version/middle_pic4.jpg","images/latest_version/middle_pic6.jpg", "images/latest_version/middle_pic7.jpg", "images/glasses-for-distance-use.jpg"); 
  whichimage = Math.floor(Math.random()*theimages.length); 
//  output = '<td height="366" background="' +theimages[whichimage]+ '">';
  document.getElementById("ranImageTd").style.background = 'url(' + theimages[whichimage] + ')';
}