var urlPrefix = '/fileadmin/IMH/www.hotel-immenhof.de/bannerpics/';
var imageUrl = Array( 1, 2, 3 );

function zoomImage( pos )
  {
    var imgLarge = document.getElementById( 'image-0' );
    var imgSmall = document.getElementById( 'image-' + pos );

    if ( imgLarge && imgSmall )
      {
        var newLarge = imageUrl[ pos ];
        imgLarge.src = urlPrefix + topicNum + '_' + newLarge + '.jpg';
        imgSmall.src = urlPrefix + topicNum + '_' + imageUrl[ 0 ] + 's.jpg';
        imageUrl[ pos ] = imageUrl[ 0 ];
        imageUrl[ 0 ] = newLarge;
      }
  }