Fade background image to new one

Fade background image to new one

I have 3 thumbs, and when I click on one of the thumb, the background of my site has to fade to the same image as the thumb. This code is working for me, but it is fading to white first, and after it fades to the new background.

function changeback(backname){
      var newsrc = "<?=SITE_WEBDIR?>img/bg/"+backname;
      $('#backimg').fadeOut(300, function(){
            $(this).attr('src',newsrc).bind('onreadystatechange load', function(){
                  if (this.complete) $(this).fadeIn(300);
            });
       });
}

I want to let the background fade to the new background directy, and not a white background first.

Any ideas?