Jquery Slidetoggle Image change

So upon .click i want to change the h3.portraits background image and then have it change back when i click again.

          
$(document).ready(function(){

 $("#portraits .container").hide();

 var up = "../images/btn-portraits-hide.png";
 var down = "../images/btn-portraits-show.png";
 $(".portraits").click(function(){
   var icon = $('.portraits', this);
   $(this).next("#portraits .container").slideToggle("slow");        
   icon.attr("src", this.attr("src") == up ? down : up);
 });

});

<div id="portraits">
 <h3 class="portraits">Portraits</h3>
 <div class="container"></div>
</div>