function okno(obrazek)
{
var odstep_gorny = (screen.height / 2) - 198;
var odstep_lewy = (screen.width / 2) - 325;

var loc = "mapa.php?pic=" + obrazek;
var attr = "width=650,height=396,top=" + odstep_gorny + ",left=" + odstep_lewy + ",scrolling=no,resize=no";
window.open(loc,"",attr);
}