def rectify(self, frames):
        """
        Rectify frames passed as (left, right) pair of OpenCV Mats.

        Remapping is done with nearest neighbor for speed.
        """
        new_frames = []
        for i, side in enumerate(("left", "right")):
            new_frames.append(cv2.remap(frames[i],
                                        self.undistortion_map[side],
                                        self.rectification_map[side],
                                        cv2.INTER_NEAREST))
        return new_frames