function show_pic(picid){
  document.getElementById("trans").className = 'trans';
  document.getElementById("gallery").className = 'gallery';
  document.getElementById("pic").innerHTML = '<a href="javascript:hide_pic();"><img class="big_pic_'+size[picid]+'" src="'+pfad+album[picid]+'"></a>';
  if(picid >= album.length-1){
    document.getElementById("back").innerHTML = '<a href="javascript:show_back('+picid+');">zurück</a>';
    document.getElementById("next").innerHTML = '<a href="javascript:show_next();"></a>';
  }
  else if(picid < 1){
    document.getElementById("back").innerHTML = '<a href="javascript:show_back();"></a>';
    document.getElementById("next").innerHTML = '<a href="javascript:show_next('+picid+');">vor</a>';
  }
  else{
    document.getElementById("back").innerHTML = '<a href="javascript:show_back('+picid+');">zurück</a>';
    document.getElementById("next").innerHTML = '<a href="javascript:show_next('+picid+');">vor</a>';
  }
}

function hide_pic(){
  document.getElementById("trans").className = 'inactive';
  document.getElementById("gallery").className = 'inactive';
  document.getElementById("pic").innerHTML = '';
  document.getElementById("back").innerHTML = '<a href="javascript:show_back();"></a>';
  document.getElementById("next").innerHTML = '<a href="javascript:show_next();"></a>';
}

function show_next(picid){
  picid++;
  javascript:show_pic(picid);
}

function show_back(picid){
  picid--;
  javascript:show_pic(picid);
}

function Position () {
  alert("pageYOffset: " + document.body.scrollTop + " Pixel");
}