var intervall;
 var myImage = null;
 function hideImage()
 {
  document.getElementById("ImagePanel").style.visibility = "hidden";
  document.getElementById("ImageBack").style.visibility = "hidden";
 }

 function showImage(img)
 {
  myImage = new Image();
  myImage.src = "images/"+img;
  intervall = window.setInterval("pruefen(myImage)", 50);
 }

function pruefen(myImage)
{

  if (myImage.complete)
  {
  window.clearInterval(intervall);

  if (!document.all)
  {
   document.getElementById("ImageBack").style.height = (window.innerHeight + window.pageYOffset)+'px';
  } else
  {
   document.getElementById("ImageBack").style.height = document.documentElement.clientHeight + document.documentElement.scrollTop;
  }

   var content = "<a href=\"Javascript:void(0)\" onClick=\"hideImage()\"><img name=\"visibleImage\" style=\"border: 0px solid black;\" src=\""+myImage.src+"\" alt=\""+myImage.src+"\"></a>";
   content += "<div style=\"margin-top: 2px; top: 0px; z-index: 100;\">&nbsp;Auf das Bild klicken um es zu schließen.</div>";

   document.getElementById("ImagePanel").innerHTML = content;

   document.getElementById("ImagePanel").style.height = document.visibleImage.height + 20;
   document.getElementById("ImagePanel").style.width = document.visibleImage.width;
   document.getElementById("ImagePanel").style.marginTop = -parseInt(document.visibleImage.height / 2 - document.documentElement.scrollTop)+'px';
   document.getElementById("ImagePanel").style.marginLeft = -parseInt(document.visibleImage.width / 2) +'px';

   document.getElementById("ImageBack").style.visibility = 'visible';
   document.getElementById("ImagePanel").style.visibility = 'visible';
  }
}