var bImagesAvailable =  document.images;
  
  if ( bImagesAvailable ) {
          var img = new Array();
          
          for ( i=1 ; i < 300 ; i++ ) {
                  img[i] = new Image();
          }

  img[1].src = "graphics/home-off.gif";
  img[2].src = "graphics/home-on.gif";

  img[3].src = "graphics/search-off.gif";
  img[4].src = "graphics/search-on.gif";

  img[5].src = "graphics/main-off.gif";
  img[6].src = "graphics/main-on.gif";

  img[11].src = "graphics/info-off.gif";
  img[12].src = "graphics/info-on.gif";

  img[17].src = "graphics/email-off.gif";
  img[18].src = "graphics/email-on.gif";  
 
  img[21].src = "graphics/knop-off1.gif";
  img[22].src = "graphics/knop-on1.gif";
  
  img[23].src = "graphics/knop-off2.gif";
  img[24].src = "graphics/knop-on2.gif";  
  
  img[27].src = "graphics/knop-off3.gif";
  img[28].src = "graphics/knop-on3.gif";

  img[31].src = "graphics/knop-off4.gif";
  img[32].src = "graphics/knop-on4.gif";

  img[33].src = "graphics/knop-off5.gif";
  img[34].src = "graphics/knop-on5.gif";  

  img[37].src = "graphics/knop-off6.gif";
  img[38].src = "graphics/knop-on6.gif";
  
  img[41].src = "graphics/knop-off7.gif";
  img[42].src = "graphics/knop-on7.gif";
  
  img[49].src = "graphics/knop-off8.gif";
  img[50].src = "graphics/knop-on8.gif";

  img[51].src = "graphics/knop-off9.gif";
  img[52].src = "graphics/knop-on9.gif";

  img[53].src = "graphics/knop-off10.gif";
  img[54].src = "graphics/knop-on10.gif";

  img[55].src = "graphics/knop-off11.gif";
  img[56].src = "graphics/knop-on11.gif";
 }
  
  function ri ( imgName, imgNumber ) {
    if (bImagesAvailable) {
      document[imgName].src = img[imgNumber].src;
    }
  }