Image changing, then changing back, then changing the next image

gistfile1.txt

$(document).ready(changer);

function changer() {
   var imgnum = Math.floor(15 * Math.random());
   var time = Math.floor(5000 * Math.random());
   var $img = $('.project_thumb .cardimgcrop img').eq(imgnum);
   var newsrc = "http://yaplog.jp/cv/omb-master/img/449/noise_p.gif";
   
   $img.css({
         'width': $img.css('width'),
         'height': $img.css('height')
   });
   $img.data("oldsrc", $img.attr("src"));
   $img.attr("src", newsrc);

   // creating timeout for changing image back
   setTimeout(function() {
      	$img.attr("src", $img.data("oldsrc"));
        // create timeout for calling the next "changer"
        setTimeout(changer, time);      	
   }, 1500);
}