preload_image_object = new Image();
      // set image url
      image_url = new Array();
      image_url[0] = "/images/global/global_top.gif";
      image_url[1] = "/images/global/pattern_step.jpg";
	  image_url[2] = "/images/subpages/center_tile.gif";
	  
       var i = 0;
       for(i=0; i<=image_url.size; i++) 
         preload_image_object.src = image_url[i];