jQuery(function() { 
  $('body#photo_list div.thumb > a > img').each(function() {
    //resize thumbnail
    var width = $(this).width();
    var height = $(this).height();
    if (width>height) {
      var ratio = width / 100;
      var new_width = 100;
      var new_height = height / ratio;
      $(this).css('width', '100px').css('margin-top', ((100 - new_height)/2) + 'px');
    }
    else {
      var ratio = height / 100;
      var new_height = 100;
      var new_width = width / ratio;
      $(this).css('height', '100px').css('margin-left', ((100 - new_width)/2) + 'px');
    }
  });
});