var core = 0;
    var now  = 0;
    var seed = 0;

    function StringArray (n) {
       this.length = n;
       for (var i = 1; i <= n; i++) {
           this[i] = ' ';
       }
    }

    image = new StringArray(12)
    image[0]  = 'images/content/h_1.jpg';
    image[1]  = 'images/content/h_2.jpg';
    image[2]  = 'images/content/h_3.jpg';
    image[3]  = 'images/content/h_4.jpg';
    image[4]  = 'images/content/h_5.jpg';
    image[5]  = 'images/content/h_6.jpg';
    image[6]  = 'images/content/h_7.jpg';
    image[7]  = 'images/content/h_8.jpg';
    image[8]  = 'images/content/h_9.jpg';
    image[9]  = 'images/content/h_10.jpg';
    image[10] = 'images/content/h_11.jpg';
    image[11] = 'images/content/h_12.jpg';

    function disp_img(w) {
       now  = new Date();
       seed = now.getSeconds();
       core = Math.floor(Math.random(seed)*(image.length));
       var img_src = image[core];
       document.ani.src = img_src;
    }
    t = setInterval("disp_img(core)", 5000);