$.fn.fadeBackgroundImage = function(bgImagesArray, randomize, fadeout, fadein, interval){
      if (fadeout==null) {
        fadeout=1000;
      }
      if (fadein==null) {
        fadein=1000;
      }
      if (interval==null) {
        interval=4000;
      }
      var containerElement = this;
      var currentBgSrc = $('#bgcontainer').css('background-image');
      var selectedIndex = 0;
      if (randomize == 'random' || randomize == 'startrandom') {
        if (randomize == 'startrandom') {
          randomize = 'normal';
        }
        if (bgImagesArray.length > 1) {
          var gotNewSrc = false;
            while (!gotNewSrc) {
            selectedIndex = Math.floor(Math.random()*bgImagesArray.length);
            if (currentBgSrc.match(bgImagesArray[selectedIndex]) == null) {
              gotNewSrc = true;
            }
          }
        }
      } else {
        for (var i=0; i<bgImagesArray.length; i++){
          if (bgImagesArray[i]==currentBgSrc) {
            if (i+1==bgImagesArray.length) {
              selectedIndex = 0;
            } else {
              selectedIndex = i+1;
            }
          }
        }
      }
      $('<img />').attr('src', bgImagesArray[selectedIndex]).load(function() {
        $('#bgcontainer').animate({opacity: 0}, fadeout, function() {
          $('#bgcontainer').css('background-image', 'url("'+bgImagesArray[selectedIndex]+'")').animate({opacity: 1}, fadein, function() {
            setTimeout(function(){ $('bgcontainer').fadeBackgroundImage(bgImagesArray, randomize, fadeout, fadein, interval) }, interval);
          });
        });
      });
      return this;
    }

    $(document).ready(function() {
       $('bgcontainer').fadeBackgroundImage(['http://www3.webio.fi/coloria/content/img/header/randomtausta1.jpg','http://www3.webio.fi/coloria/content/img/header/randomtausta2.jpg','http://www3.webio.fi/coloria/content/img/header/randomtausta3.jpg'], 'random', 1000, 2000, 8000);
    });