function rollover(imgID, imgName) {
  // get the image object we're referring to
  var thisimg = document.getElementById(imgID);
  // and add "_r" to its src
  //thisimg.src = thisimg.src.replace(/(\.[a-z0-9]+)$/i,'_r$1');
  thisimg.src = imgName;
}
function rollout(imgID, imgName) {
  // get the image object we're referring to
  var thisimg = document.getElementById(imgID);
  // and remove "_r" from its src
  //thisimg.src = thisimg.src.replace(/_r(\.[a-z0-9]+)$/i,'$1');
  thisimg.src = imgName;
}