var aktiv;
var img;
var img_index;
var img_count = 5;
var steps_total = 40;
var steps_done = new Array(0, 0, 0, 0, 0);
var opacity_increment = 1 / steps_total;
var browser = navigator.appName;


function fade_in() {

  steps_done[img_index]++;

  if ('Microsoft Internet Explorer' == browser) {
    img.style.filter = 'alpha(opacity = ' + 100 * steps_done[img_index] * opacity_increment + ')';
  } else {
    img.style.opacity = steps_done[img_index] * opacity_increment;
  }

  if (steps_total == steps_done[img_index]) {

    img_index++;

    if (img_count > img_index) {
      fetch_image('id_header_image_' + (img_index + 1));
    } else {
      window.clearInterval(aktiv);
    }
  }
}


function fetch_image(id_img) {

  img = document.getElementById(id_img);

  if ('Microsoft Internet Explorer' == browser) {
    img.style.filter = 'alpha(opacity = 0)';
  } else {
    img.style.opacity = 0.0;
  }
}