function CargarFoto(img, ancho, alto){
derecha=((screen.width-ancho)/2);
arriba=((screen.height-alto)/2);
string="toolbar=0,scrollbars=0,location=0,statusbar=0,menu bar=0,resizable=0,width="+ancho+",height="+alto+",left="+derecha+",top="+arriba+"";
fin=window.open(img,"",string);
}