function zoomImage (imageElement, xFactor, yFactor) {
  imageElement.width =
    Math.round(document.imageName.width * xFactor);
  imageElement.height = 
    Math.round(document.imageName.height * yFactor);
  if (imageElement.useMap)
    zoomMap (imageElement.useMap.substring(1), xFactor, yFactor);
}
function zoomMap (mapName, xFactor, yFactor) {
  if (document.all) {
    var map = document.all[mapName];
    var areas = map.all.tags('AREA');
  }
  else if (document.getElementsByName) {
    var map = document.getElementsByName(mapName)[0];
    var areas = map.getElementsByTagName('AREA');
  }
  if (areas) {
    for (var a = 0; a < areas.length; a++) {
      var coords = areas[a].coords.split(/\s*,\s*/);
      if (areas[a].shape.toLowerCase() == 'rect' ||
          areas[a].shape.toLowerCase() == 'poly') {
        for (var p = 0; p < coords.length; p += 2) {
          coords[p] = Math.round(coords[p] * xFactor);
          coords[p + 1] = Math.round(coords[p + 1] * yFactor);
        }
      }
      else if (areas[a].shape.toLowerCase() == 'circle') {
        coords[0] = Math.round(coords[0] * xFactor);
        coords[1] = Math.round(coords[1] * yFactor);
        coords[2] = Math.round(coords[2] * (xFactor < yFactor ? xFactor 
: yFactor));
      }
      areas[a].coords = coords.join(', ');
    }
  }
}