<!--
obr1=new Image();
obr1.src="images/b1a.jpg";
obr2=new Image();
obr2.src="images/b2a.jpg";
obr3=new Image();
obr3.src="images/b3a.jpg";
obr4=new Image();
obr4.src="images/b4a.jpg";
function zamen (nazev_obr,novy_obr)
{
  document.images[nazev_obr].src=novy_obr;
}
// -->