var myimages=new Array();
function preloadimages() {
 for (i=0;i<preloadimages.arguments.length;i++)
 {
  myimages[i]=new Image()
  myimages[i].src=preloadimages.arguments[i]
 }
}
function preload() {
 preloadimages('fileadmin/img/header/skoliose/bild1.jpg',
               'fileadmin/img/header/skoliose/bild2.jpg',
        		   'fileadmin/img/header/skoliose/bild3.jpg',
        		   'fileadmin/img/header/skoliose/bild4.jpg');
}

			function imgposition(tbl) {
				if(document.all) {
				  
				}
				else {
				  var width = window.innerWidth;
				  var height = window.innerHeight;
				}
				// document.div.height
				alert(document.tbl.height);
			}
		
			function setrandimg() {
				var rand = Math.floor(Math.random()*(4))+1;
				document.getElementById('bgimage').src = 'fileadmin/img/header/skoliose/bild' + rand + '.jpg';
			}