var activpic   = '1';
var inactivpic = '2';
var steps      = 0.1;

function swap_images()
{
  var prozent = document.getElementById('bild'+activpic).style.MozOpacity;
  prozent = prozent - steps;

  if(isNaN(prozent))
  {
    prozent = document.getElementById('bild'+activpic).style.filter.match(/[0-9]{1,3}/);
    prozent = Math.round(prozent) / 100;
  }

  // �ndern des aktiven Bildes
  document.getElementById('bild'+activpic).style.MozOpacity = prozent;
  document.getElementById('bild'+activpic).style.filter='Alpha(opacity='+(prozent*100)+')';


  // �ndern des inaktiven Bildes
  document.getElementById('bild'+inactivpic).style.MozOpacity = (1-prozent);
  document.getElementById('bild'+inactivpic).style.filter='Alpha(opacity='+((1-prozent)*100)+')';

  if(prozent <= 0)
  {

    document.getElementById('bild'+activpic).style.MozOpacity = 0;
    document.getElementById('bild'+activpic).style.filter='Alpha(opacity=0)';
    document.getElementById('bild'+inactivpic).style.MozOpacity = 1;
    document.getElementById('bild'+inactivpic).style.filter='Alpha(opacity=100)';

    var temp   = activpic;
    activpic   = inactivpic;
    inactivpic = temp;

    // Bild austauschen beim inaktivem Bild
    var bild1 = document.getElementById('anz_bild'+inactivpic).src;
    var bild2 = document.getElementById('anz_bild'+activpic).src;

    var zufall = 0;
    var newpic = '';
    zufall = Math.round(Math.random()*bilder.length);

    //alert(zufall);
    //alert(bild1);
    //alert(bild2);
    //alert(bilder.length);
    while(newpic == '')
    {
      if(zufall >= bilder.length || zufall < 1)
      {
        //alert('tohigh: '+zufall);
        zufall = 1;
      }
      if(bild1.search(bilder[zufall]) == -1 && bild2.search(bilder[zufall]) == -1)
      {
        //alert('found as free: '+zufall);
        newpic = bilder[zufall];
      }
      else
        zufall++;
    }

    //alert(zufall+'|'+newpic);
    document.getElementById('anz_bild'+inactivpic).src=newpic;
    window.setTimeout('swap_images()', 9000);
  }
  else
  {
    window.setTimeout('swap_images()', 100);
  }
}
window.setTimeout('swap_images()', 1000);