// JavaScript Document
function change_img(obj)
{
  object = eval("document." + obj);
  object.src= imgA.src;
}

function change_back(obj)
{
  object = eval("document."+ obj);
  object.src = imgB.src;
}

imgA = new Image();
imgB = new Image();
imgA.src="../Bilder/tik.gif"
imgB.src="../Bilder/tik2.gif"