wrapper for im_detect and visualize_detection

        Parameters:
        ----------
        im_list : list of str or str
            image path or list of image paths
        root_dir : str or None
            directory of input images, optional if image path already
            has full directory information
        extension : str or None
            image extension, eg. ".jpg", optional

        Returns:
        ----------

def detect_and_visualize(self, im_list, root_dir=None, extension=None,
                             classes=[], thresh=0.6, show_timer=False):
        """
        wrapper for im_detect and visualize_detection

        Parameters:
        ----------
        im_list : list of str or str
            image path or list of image paths
        root_dir : str or None
            directory of input images, optional if image path already
            has full directory information
        extension : str or None
            image extension, eg. ".jpg", optional

        Returns:
        ----------

        """
        dets = self.im_detect(im_list, root_dir, extension, show_timer=show_timer)
        if not isinstance(im_list, list):
            im_list = [im_list]
        assert len(dets) == len(im_list)
        for k, det in enumerate(dets):
            img = cv2.imread(im_list[k])
            img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
            self.visualize_detection(img, det, classes, thresh)