if (document.images) {
  image_off = new Image();
  image_off.src = '/avomesserli/images/point_trans.gif';
  image_on = new Image();
  image_on.src = '/avomesserli/images/point_half.gif';
}

function changeImages(Image,Object)
{
  if (document.images)
    document[Image].src = Object.src;
}