How to use the perception.primesense_sensor.PrimesenseSensor function in Perception

def _read_depth_image(self):
        """ Reads a depth image from the device """
        # read raw uint16 buffer
        im_arr = self._depth_stream.read_frame()
        raw_buf = im_arr.get_buffer_as_uint16()
        buf_array = np.array([raw_buf[i] for i in range(PrimesenseSensor.DEPTH_IM_WIDTH * PrimesenseSensor.DEPTH_IM_HEIGHT)])

        # convert to image in meters
        depth_image = buf_array.reshape(PrimesenseSensor.DEPTH_IM_HEIGHT,
                                        PrimesenseSensor.DEPTH_IM_WIDTH)
        depth_image = depth_image * MM_TO_METERS # convert to meters
        if self._flip_images:
            depth_image = np.flipud(depth_image)
        else:
            depth_image = np.fliplr(depth_image)
        return DepthImage(depth_image, frame=self._frame)

def start(self):
        """ Start the sensor """
        # open device
        openni2.initialize(PrimesenseSensor.OPENNI2_PATH)
        self._device = openni2.Device.open_any()

        # open depth stream
        self._depth_stream = self._device.create_depth_stream()
        self._depth_stream.configure_mode(PrimesenseSensor.DEPTH_IM_WIDTH,
                                          PrimesenseSensor.DEPTH_IM_HEIGHT,
                                          PrimesenseSensor.FPS,
                                          openni2.PIXEL_FORMAT_DEPTH_1_MM) 
        self._depth_stream.start()

        # open color stream
        self._color_stream = self._device.create_color_stream()
        self._color_stream.configure_mode(PrimesenseSensor.COLOR_IM_WIDTH,
                                          PrimesenseSensor.COLOR_IM_HEIGHT,
                                          PrimesenseSensor.FPS,
                                          openni2.PIXEL_FORMAT_RGB888)

def color_intrinsics(self):
        """:obj:`CameraIntrinsics` : The camera intrinsics for the primesense color camera.
        """
        return CameraIntrinsics(self._ir_frame, PrimesenseSensor.FOCAL_X, PrimesenseSensor.FOCAL_Y,
                                PrimesenseSensor.CENTER_X, PrimesenseSensor.CENTER_Y,
                                height=PrimesenseSensor.DEPTH_IM_HEIGHT,
                                width=PrimesenseSensor.DEPTH_IM_WIDTH)

def ir_intrinsics(self):
        """:obj:`CameraIntrinsics` : The camera intrinsics for the primesense IR camera.
        """
        return CameraIntrinsics(self._ir_frame, PrimesenseSensor.FOCAL_X, PrimesenseSensor.FOCAL_Y,
                                PrimesenseSensor.CENTER_X, PrimesenseSensor.CENTER_Y,
                                height=PrimesenseSensor.DEPTH_IM_HEIGHT,
                                width=PrimesenseSensor.DEPTH_IM_WIDTH)

def _read_color_image(self):
        """ Reads a color image from the device """
        # read raw buffer
        im_arr = self._color_stream.read_frame()
        raw_buf = im_arr.get_buffer_as_triplet()
        r_array = np.array([raw_buf[i][0] for i in range(PrimesenseSensor.COLOR_IM_WIDTH * PrimesenseSensor.COLOR_IM_HEIGHT)])        
        g_array = np.array([raw_buf[i][1] for i in range(PrimesenseSensor.COLOR_IM_WIDTH * PrimesenseSensor.COLOR_IM_HEIGHT)])        
        b_array = np.array([raw_buf[i][2] for i in range(PrimesenseSensor.COLOR_IM_WIDTH * PrimesenseSensor.COLOR_IM_HEIGHT)])        

        # convert to uint8 image
        color_image = np.zeros([PrimesenseSensor.COLOR_IM_HEIGHT, PrimesenseSensor.COLOR_IM_WIDTH, 3])
        color_image[:,:,0] = r_array.reshape(PrimesenseSensor.COLOR_IM_HEIGHT,
                                             PrimesenseSensor.COLOR_IM_WIDTH)
        color_image[:,:,1] = g_array.reshape(PrimesenseSensor.COLOR_IM_HEIGHT,
                                             PrimesenseSensor.COLOR_IM_WIDTH)
        color_image[:,:,2] = b_array.reshape(PrimesenseSensor.COLOR_IM_HEIGHT,
                                             PrimesenseSensor.COLOR_IM_WIDTH)
        if self._flip_images:
            color_image = np.flipud(color_image.astype(np.uint8))
        else:
            color_image = np.fliplr(color_image.astype(np.uint8))
        return ColorImage(color_image, frame=self._frame)

def ir_intrinsics(self):
        """:obj:`CameraIntrinsics` : The camera intrinsics for the primesense IR camera.
        """
        return CameraIntrinsics(self._ir_frame, PrimesenseSensor.FOCAL_X, PrimesenseSensor.FOCAL_Y,
                                PrimesenseSensor.CENTER_X, PrimesenseSensor.CENTER_Y,
                                height=PrimesenseSensor.DEPTH_IM_HEIGHT,
                                width=PrimesenseSensor.DEPTH_IM_WIDTH)

openni2.initialize(PrimesenseSensor.OPENNI2_PATH)
        self._device = openni2.Device.open_any()

        # open depth stream
        self._depth_stream = self._device.create_depth_stream()
        self._depth_stream.configure_mode(PrimesenseSensor.DEPTH_IM_WIDTH,
                                          PrimesenseSensor.DEPTH_IM_HEIGHT,
                                          PrimesenseSensor.FPS,
                                          openni2.PIXEL_FORMAT_DEPTH_1_MM) 
        self._depth_stream.start()

        # open color stream
        self._color_stream = self._device.create_color_stream()
        self._color_stream.configure_mode(PrimesenseSensor.COLOR_IM_WIDTH,
                                          PrimesenseSensor.COLOR_IM_HEIGHT,
                                          PrimesenseSensor.FPS,
                                          openni2.PIXEL_FORMAT_RGB888) 
        self._color_stream.camera.set_auto_white_balance(self._auto_white_balance)
        self._color_stream.camera.set_auto_exposure(self._auto_exposure)
        self._color_stream.start()

        # configure device
        if self._registration_mode == PrimesenseRegistrationMode.DEPTH_TO_COLOR:
            self._device.set_image_registration_mode(openni2.IMAGE_REGISTRATION_DEPTH_TO_COLOR)
        else:
            self._device.set_image_registration_mode(openni2.IMAGE_REGISTRATION_OFF)

        self._device.set_depth_color_sync_enabled(self._enable_depth_color_sync)

        self._running = True

def _read_color_image(self):
        """ Reads a color image from the device """
        # read raw buffer
        im_arr = self._color_stream.read_frame()
        raw_buf = im_arr.get_buffer_as_triplet()
        r_array = np.array([raw_buf[i][0] for i in range(PrimesenseSensor.COLOR_IM_WIDTH * PrimesenseSensor.COLOR_IM_HEIGHT)])        
        g_array = np.array([raw_buf[i][1] for i in range(PrimesenseSensor.COLOR_IM_WIDTH * PrimesenseSensor.COLOR_IM_HEIGHT)])        
        b_array = np.array([raw_buf[i][2] for i in range(PrimesenseSensor.COLOR_IM_WIDTH * PrimesenseSensor.COLOR_IM_HEIGHT)])        

        # convert to uint8 image
        color_image = np.zeros([PrimesenseSensor.COLOR_IM_HEIGHT, PrimesenseSensor.COLOR_IM_WIDTH, 3])
        color_image[:,:,0] = r_array.reshape(PrimesenseSensor.COLOR_IM_HEIGHT,
                                             PrimesenseSensor.COLOR_IM_WIDTH)
        color_image[:,:,1] = g_array.reshape(PrimesenseSensor.COLOR_IM_HEIGHT,
                                             PrimesenseSensor.COLOR_IM_WIDTH)
        color_image[:,:,2] = b_array.reshape(PrimesenseSensor.COLOR_IM_HEIGHT,
                                             PrimesenseSensor.COLOR_IM_WIDTH)
        if self._flip_images:
            color_image = np.flipud(color_image.astype(np.uint8))
        else:
            color_image = np.fliplr(color_image.astype(np.uint8))
        return ColorImage(color_image, frame=self._frame)

The number of consecutive frames to process.

        Returns
        -------
        :obj:`DepthImage`
            The min DepthImage collected from the frames.
        """
        depths = []

        for _ in range(num_img):
            _, depth, _ = self.frames()
            depths.append(depth)

        return Image.min_images(depths)

class PrimesenseSensor_ROS(PrimesenseSensor):
    """ ROS-based version of Primesense RGBD sensor interface
    
    Requires starting the openni2 ROS driver and the two stream_image_buffer (image_buffer.py)
    ros services for depth and color images. By default, the class will look for the depth_image buffer
    and color_image buffers under "{frame}/depth/stream_image_buffer" and "{frame}/rgb/stream_image_buffer"
    respectively (within the current ROS namespace).
    
    This can be changed by passing in depth_image_buffer, color_image_buffer (which change where the program
    looks for the buffer services) and depth_absolute, color_absolute (which changes whether the program prepends
    the current ROS namespace).
    """
    def __init__(self, depth_image_buffer= None, depth_absolute=False, color_image_buffer=None, color_absolute=False,
                 flip_images=True, frame=None, staleness_limit=10., timeout=10):  
        import rospy
        from rospy import numpy_msg
        from perception.srv import ImageBufferResponse