var datum;
var sec;   
function changeBild() 
{ 
datum = new Date();  
sec = datum.getSeconds();	  
if ( sec <= 15 ) 
{
document.getElementById("kep").src="images/Kep1.jpg";	  
} else if ( sec <= 30 ) {
document.getElementById("kep").src="images/Kep2.jpg";	  
} else if ( sec <= 45 ) {
document.getElementById("kep").src="images/Kep3.jpg";	  
} else {
document.getElementById("kep").src="images/Kep4.jpg";	  
}
setTimeout("changeBild()",1000);	
}