var arrayimages = new Array(2);

  arrayimages[0] = "images/pictour/hungwhl_ext.jpg";
  arrayimages[1] = "images/pictour/hwc_int_1.jpg";
  arrayimages[2] = "images/pictour/hwc_int_2.jpg";
  arrayimages[3] = "images/pictour/hwc_int_3.jpg";
  arrayimages[4] = "images/pictour/hwc_int_4.jpg";

 
  for (i=0; i < arrayimages.length; i++) {
    var preload = new Image();
    preload.src = arrayimages[i];
  }

  function swap(imgIndex) {
    document['imgmain'].src = arrayimages[imgIndex];
  }