function rotateHeader (imgName, imgFormat)
{
   var imgCount = 9;
   var bgImage = "/images/" + imgName + Math.floor(Math.random()*imgCount+1) + imgFormat;

   document.getElementById(imgName).style.background = "url('" + bgImage + "') top left no-repeat #ffffff";
}

function rotateImage (imgName, imgCount, imgFormat)
{
   document.getElementById(imgName).src = "/images/" + imgName + Math.floor(Math.random()*imgCount+1) + imgFormat;
}