function Foto(url,w,h) {
  if(screen.width>w) wwidth = w; else wwidth = screen.width;
  if(screen.height>h) wheight = h; else wheight = screen.height;
  wtop = screen.height/2-wheight/2;
  wleft = screen.width/2-wwidth/2;
  window.open('foto.html?f='+url+'&w='+w+'&h='+h,'','width='+wwidth+',height='+wheight+',top='+wtop+',left='+wleft+',status=yes,resizable=yes');
}