function swapSmallImages(img)
{
  imageSrc = document.getElementById(img).src;
  mainSrc = document.getElementById('mainImage').src;
  document.getElementById(img).src = mainSrc.substr(0,mainSrc.length-5)+'1.jpg';
  document.getElementById('mainImage').src = imageSrc.substr(0,imageSrc.length-5)+'3.jpg';;
  return false;
}
function swapImages()
{
  imageSrc = document.getElementById('centralImage').src;
  mainSrc = document.getElementById('mainImage').src;
  document.getElementById('centralImage').src = mainSrc.substr(0,mainSrc.length-5)+'2.jpg';
  document.getElementById('mainImage').src = imageSrc.substr(0,imageSrc.length-5)+'3.jpg';;
  return false;
}