var i = 1, j = i+1, flag = true;
var img1 = new Image();
var img2 = new Image();
img1.src = img_src(images[i]);
img2.src = img_src(images[j]);

function image_is_loaded(img) {
 if (!img.complete)
  return false;
 else if (typeof img.naturalWidth != "undefined" && img.naturalWidth == 0)
  return false;
 else
  return true;
}

function img_src(src) {
 return 'images/header/' + src;
}

function rotate() {
 var p = navigator.userAgent.indexOf('MSIE');
 if(p!=-1) {
  var ver = parseFloat(navigator.userAgent.substring(p+5));
  if(ver<7) {
   return;
  }
 }
 setInterval('rotate_header_images()',5000);
}

function rotate_header_images() {
 var delay = 15;
 var step = 1;
 var min_opacity = step + 10;
 var div1_id,div2_id,code;
 if(image_is_loaded(img1) && image_is_loaded(img2)) {
  if(flag) {
   div1_id = 'header-image-1';
   div2_id = 'header-image-2';
  }
  else {
   div1_id = 'header-image-2';
   div2_id = 'header-image-1';
  }
  code = 'set_transparency("'+div2_id+'",'+min_opacity+');';
  code += 'document.getElementById("'+div2_id+'").style.backgroundImage="url("+img_src(images[i])+")";';
  eval(code);
  var l=min_opacity-step;
  if(true) {
   for(var k=100;k>=min_opacity;k=k-step,l=l+step) {
    code = 'set_transparency("'+div1_id+'",'+k+');';
    setTimeout(code,(100-k)*delay);
    code = 'set_transparency("'+div2_id+'",'+l+');';
    setTimeout(code,(l-min_opacity)*delay);
   }
  }
  code = 'set_transparency("'+div1_id+'",0);';
  code += 'document.getElementById("'+div1_id+'").style.backgroundImage="url("+img_src(images[j])+")";';
  setTimeout(code,(100-min_opacity)*delay);
 }
 i++;
 if(i>=images.length) {
  i = 0;
 }
 img1.src = img_src(images[i]);
 j++;
 if(j>=images.length) {
  j = 0;
 }
 img2.src = img_src(images[j]);
 if(flag) {
  flag = false;
 }
 else {
  flag = true;
 }
}

function set_transparency(id,opacity) {
 var style = document.getElementById(id).style;
 style.opacity = opacity/100;
 style.filter = 'alpha(opacity=' + opacity + ')';
}