function swapImg(){
      var $defimg = $('#img_header .active');
      var $next = ($('#img_header .active').next().length > 0) ? $('#img_header .active').next() : $('#img_header img:first');
      $defimg.fadeOut(function(){
      $defimg.removeClass('active');
      $next.fadeIn(1500).addClass('active');
      });
    }

    $(document).ready(function(){
      // swap img every 5secs
      setInterval('swapImg()', 6000);
    });