function preload() {
  if (!document.images) return;
  var ar = new Array();
  var arguments = preload.arguments;
  for (var i = 0; i < arguments.length; i++) {
    ar[i] = new Image();
    ar[i].src = arguments[i];
  }
}

function pic_caption(image,caption)
  {
  var txt=document.getElementById("gallery_caption")
  var gallery_img = image;
  var gallery_caption = caption;
  txt.innerHTML= gallery_caption;
  document.MyImage.src= gallery_img;
  }