$(document).ready(function(){

  var curSel = ".lightbox";
    if ($(curSel).length)
    {
        $(curSel).each(function(){
            if ($(this).attr('href').search(/logo/i) == -1)
            {
                $(this).attr('rel', 'slideshow');
            }
        });
        $(curSel).lightbox({fitToScreen: false});
    }

});