var normal;
var zoom;

function setNormal( nm )
{
  normal = new Image();
  normal.src = nm;
}

function setZoom( nm )
{
  zoom = new Image();
  zoom.src = nm;
}

function zoomin( nm )
{
  document.images[nm].src = zoom.src;
}

function zoomout( nm )
{
  document.images[nm].src = normal.src;
}