function kol_det(obj) {
  var src = obj.src;
  if (src == null)
    return;
  if (src && src.length > 6 && src.search(/[0-9]{2}(.jpg)$/) > -1) {
    src = src.substring(0, src.length - 4) + "a.jpg";
    win = window.open("kolekce-detail.html?url=" + src, "null", "width=460,height=400'");
    win.moveTo(100, 100);
    win.resizeTo(460, 400);
    win.focus();
  }
}