var bigPicture;
  window.addEvent('load', function() {
    bigPicture = new Fx.Style('bigPicture', 'opacity', { duration: 200, wait: false });
  });

  function update(gallery, pic_id, caption) {
    var bigPic = 'bigPicture_'+gallery;
    var bigPicCaption = 'bigPictureCaption_'+gallery;
    var newPic = eval('img_'+gallery+'_'+pic_id+'.src');
    var thisPic = new Fx.Style(bigPic, 'opacity', { duration: 200, wait: false });
    var picCaption = new Fx.Style(bigPicCaption, 'opacity', { duration: 200 });
    if ($(bigPic).src == newPic) {
      return;
    }
    picCaption.start(1,0).chain(function() {
      thisPic.start(0,1);
      picCaption.start(0,1);
    });
    thisPic.start(1,0).chain(function() {
      $(bigPic).src = newPic;
      $(bigPic).alt = caption;
      $(bigPicCaption).innerHTML = caption;
    });
  }

  function fadein(id) {
    var myFade = new Fx.Style(id, 'opacity', { duration: 2000, wait: false });
    myFade.start(0,1);
  }