(function($){
  $.fn.extend({
  
    imagehover: function(standard, hover) {
      return this.each(function() {

        standard = standard || ".standard";
        hover = hover || ".hover";
        
        $(this).children(hover).hide();
        $(this)
        .mouseenter(function() { 
          $(this).children(standard).hide(); 
          $(this).children(hover).show();
        })
        .mouseleave(function() { 
          $(this).children(hover).hide(); 
          $(this).children(standard).show();
        });

      });
    }
  });
})(jQuery);