function img()
{
  num = Math.floor(18*Math.random()+1);

  document.write('<input name="imageField" type="image" border=0 src="imgSecurity/' + num + '834567.jpg" width="180" height="80" >');
  document.write('<td><input name="vIm" id="vIm"  runat="server" type="hidden" value=' + num + '834567.jpg></td>');
}