ios 7 bar button Image change

 UIImage *temp = [[UIImage imageNamed:@"Log out.png"] imageWithRenderingMode: UIImageRenderingModeAlwaysOriginal];

    UIBarButtonItem *barButtonItem = [[UIBarButtonItem alloc] initWithImage:temp style:UIBarButtonItemStyleBordered target:appDelegate action:@selector(logOutTapped)];

    self.navigationItem.rightBarButtonItem = barButtonItem;