function showpicture(picnumber)
  {
    document.getElementById('picture').src = document.getElementById("all_images").getElementsByTagName("p")[picnumber].childNodes[0].nodeValue;
    document.getElementById('picdiv').style.display = 'inline';
    var newHeight = document.body.clientHeight;
    var newWidth = document.body.clientWidth;
    document.getElementById('picdiv').style.width = newWidth;
    document.getElementById('picdiv').style.height = newHeight;
    document.getElementById('foto_table').height = newHeight;
    
    var img_width = document.getElementById('all_images').getElementsByTagName("p")[picnumber].childNodes[2].nodeValue;
    var img_height = document.getElementById('all_images').getElementsByTagName("p")[picnumber].childNodes[4].nodeValue;
    
    var new_img_width = img_width;
    var new_img_height = img_height;
    var picVerh = (img_width / img_height);
    if (newWidth < img_width)
    {
      new_img_width = (newWidth * 0.7);
      new_img_height = (new_img_width / picVerh);
    }
    else
    {
      if (newHeight < img_height)
      {
        new_img_height = (newHeight * 0.7);
        new_img_width = (new_img_height * picVerh);
      }
    }
    document.getElementById('picture').width = new_img_width;
    document.getElementById('picture').height = new_img_height;
    
    var picnumber_next = picnumber;
    var last_picnumber = document.getElementById("all_images").childNodes.length;
    ++picnumber_next;
    var next = document.getElementById('next');
    next.href = 'javascript:showpicture('+picnumber_next+')';
    if (picnumber_next >= ((last_picnumber - 1) / 2))
    {
      document.getElementById('next').style.visibility = 'hidden';
    }
    else
    {
    document.getElementById('next').style.visibility = 'visible';
    }
    
    var picnumber_back = picnumber;
    --picnumber_back;
    var back = document.getElementById('back');
    back.href = 'javascript:showpicture('+picnumber_back+')';
    if (picnumber_back < 0)
    {
      document.getElementById('back').style.visibility = 'hidden';
    }
    else
    {
    document.getElementById('back').style.visibility = 'visible';
    }
  }
  
  function hidepicture()
  {
    document.getElementById('picdiv').style.display = 'none';
    document.getElementById('picture').src = '';
  }