Python object_detection.utils.shape_utils.static_or_dynamic_map_fn() Examples

def test_with_dynamic_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.placeholder(tf.float32, shape=(None, 2))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2], [3, 1], [0, 4]]})
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1], [0, 9]]})
      self.assertAllEqual(result1, [3, 4, 4])
      self.assertAllEqual(result2, [0, 9]) 

def test_with_dynamic_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.placeholder(tf.float32, shape=(None, 2))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2], [3, 1], [0, 4]]})
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1], [0, 9]]})
      self.assertAllEqual(result1, [3, 4, 4])
      self.assertAllEqual(result2, [0, 9]) 

def test_with_dynamic_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.placeholder(tf.float32, shape=(None, 2))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2], [3, 1], [0, 4]]})
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1], [0, 9]]})
      self.assertAllEqual(result1, [3, 4, 4])
      self.assertAllEqual(result2, [0, 9]) 

def test_with_multiple_static_shapes(self):
    def fn(elems):
      input_tensor, scalar_index_tensor = elems
      return tf.reshape(tf.slice(input_tensor, scalar_index_tensor, [1]), [])

    input_tensor = tf.constant([[1, 2, 3], [4, 5, -1], [0, 6, 9]],
                               dtype=tf.float32)
    scalar_index_tensor = tf.constant([[0], [2], [1]], dtype=tf.int32)
    map_fn_output = shape_utils.static_or_dynamic_map_fn(
        fn, [input_tensor, scalar_index_tensor], dtype=tf.float32)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(all(['map' != op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result = sess.run(map_fn_output)
      self.assertAllEqual(result, [1, -1, 6]) 

def test_with_multiple_static_shapes(self):
    def fn(elems):
      input_tensor, scalar_index_tensor = elems
      return tf.reshape(tf.slice(input_tensor, scalar_index_tensor, [1]), [])

    input_tensor = tf.constant([[1, 2, 3], [4, 5, -1], [0, 6, 9]],
                               dtype=tf.float32)
    scalar_index_tensor = tf.constant([[0], [2], [1]], dtype=tf.int32)
    map_fn_output = shape_utils.static_or_dynamic_map_fn(
        fn, [input_tensor, scalar_index_tensor], dtype=tf.float32)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(all(['map' != op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result = sess.run(map_fn_output)
      self.assertAllEqual(result, [1, -1, 6]) 

def test_with_dynamic_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.placeholder(tf.float32, shape=(None, 2))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2], [3, 1], [0, 4]]})
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1], [0, 9]]})
      self.assertAllEqual(result1, [3, 4, 4])
      self.assertAllEqual(result2, [0, 9]) 

def test_with_dynamic_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.placeholder(tf.float32, shape=(None, 2))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2], [3, 1], [0, 4]]})
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1], [0, 9]]})
      self.assertAllEqual(result1, [3, 4, 4])
      self.assertAllEqual(result2, [0, 9]) 

def test_with_multiple_static_shapes(self):
    def fn(elems):
      input_tensor, scalar_index_tensor = elems
      return tf.reshape(tf.slice(input_tensor, scalar_index_tensor, [1]), [])

    input_tensor = tf.constant([[1, 2, 3], [4, 5, -1], [0, 6, 9]],
                               dtype=tf.float32)
    scalar_index_tensor = tf.constant([[0], [2], [1]], dtype=tf.int32)
    map_fn_output = shape_utils.static_or_dynamic_map_fn(
        fn, [input_tensor, scalar_index_tensor], dtype=tf.float32)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(all(['map' != op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result = sess.run(map_fn_output)
      self.assertAllEqual(result, [1, -1, 6]) 

def test_with_dynamic_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.placeholder(tf.float32, shape=(None, 2))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2], [3, 1], [0, 4]]})
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1], [0, 9]]})
      self.assertAllEqual(result1, [3, 4, 4])
      self.assertAllEqual(result2, [0, 9]) 

def test_with_multiple_static_shapes(self):
    def fn(elems):
      input_tensor, scalar_index_tensor = elems
      return tf.reshape(tf.slice(input_tensor, scalar_index_tensor, [1]), [])

    input_tensor = tf.constant([[1, 2, 3], [4, 5, -1], [0, 6, 9]],
                               dtype=tf.float32)
    scalar_index_tensor = tf.constant([[0], [2], [1]], dtype=tf.int32)
    map_fn_output = shape_utils.static_or_dynamic_map_fn(
        fn, [input_tensor, scalar_index_tensor], dtype=tf.float32)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(all(['map' != op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result = sess.run(map_fn_output)
      self.assertAllEqual(result, [1, -1, 6]) 

def test_with_dynamic_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.placeholder(tf.float32, shape=(None, 2))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2], [3, 1], [0, 4]]})
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1], [0, 9]]})
      self.assertAllEqual(result1, [3, 4, 4])
      self.assertAllEqual(result2, [0, 9]) 

def test_with_dynamic_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.placeholder(tf.float32, shape=(None, 2))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2], [3, 1], [0, 4]]})
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1], [0, 9]]})
      self.assertAllEqual(result1, [3, 4, 4])
      self.assertAllEqual(result2, [0, 9]) 

def test_with_multiple_static_shapes(self):
    def fn(elems):
      input_tensor, scalar_index_tensor = elems
      return tf.reshape(tf.slice(input_tensor, scalar_index_tensor, [1]), [])

    input_tensor = tf.constant([[1, 2, 3], [4, 5, -1], [0, 6, 9]],
                               dtype=tf.float32)
    scalar_index_tensor = tf.constant([[0], [2], [1]], dtype=tf.int32)
    map_fn_output = shape_utils.static_or_dynamic_map_fn(
        fn, [input_tensor, scalar_index_tensor], dtype=tf.float32)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(all(['map' != op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result = sess.run(map_fn_output)
      self.assertAllEqual(result, [1, -1, 6]) 

def test_with_dynamic_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.placeholder(tf.float32, shape=(None, 2))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2], [3, 1], [0, 4]]})
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1], [0, 9]]})
      self.assertAllEqual(result1, [3, 4, 4])
      self.assertAllEqual(result2, [0, 9]) 

def test_with_multiple_static_shapes(self):
    def fn(elems):
      input_tensor, scalar_index_tensor = elems
      return tf.reshape(tf.slice(input_tensor, scalar_index_tensor, [1]), [])

    input_tensor = tf.constant([[1, 2, 3], [4, 5, -1], [0, 6, 9]],
                               dtype=tf.float32)
    scalar_index_tensor = tf.constant([[0], [2], [1]], dtype=tf.int32)
    map_fn_output = shape_utils.static_or_dynamic_map_fn(
        fn, [input_tensor, scalar_index_tensor], dtype=tf.float32)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(all(['map' != op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result = sess.run(map_fn_output)
      self.assertAllEqual(result, [1, -1, 6]) 

def test_with_multiple_static_shapes(self):
    def fn(elems):
      input_tensor, scalar_index_tensor = elems
      return tf.reshape(tf.slice(input_tensor, scalar_index_tensor, [1]), [])

    input_tensor = tf.constant([[1, 2, 3], [4, 5, -1], [0, 6, 9]],
                               dtype=tf.float32)
    scalar_index_tensor = tf.constant([[0], [2], [1]], dtype=tf.int32)
    map_fn_output = shape_utils.static_or_dynamic_map_fn(
        fn, [input_tensor, scalar_index_tensor], dtype=tf.float32)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(all(['map' != op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result = sess.run(map_fn_output)
      self.assertAllEqual(result, [1, -1, 6]) 

def _tf_example_input_placeholder():
  """Returns input that accepts a batch of strings with tf examples.

  Returns:
    a tuple of input placeholder and the output decoded images.
  """
  batch_tf_example_placeholder = tf.placeholder(
      tf.string, shape=[None], name='tf_example')
  def decode(tf_example_string_tensor):
    tensor_dict = tf_example_decoder.TfExampleDecoder().decode(
        tf_example_string_tensor)
    image_tensor = tensor_dict[fields.InputDataFields.image]
    return image_tensor
  return (batch_tf_example_placeholder,
          shape_utils.static_or_dynamic_map_fn(
              decode,
              elems=batch_tf_example_placeholder,
              dtype=tf.uint8,
              parallel_iterations=32,
              back_prop=False)) 

def test_with_dynamic_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.placeholder(tf.float32, shape=(None, 2))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2], [3, 1], [0, 4]]})
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1], [0, 9]]})
      self.assertAllEqual(result1, [3, 4, 4])
      self.assertAllEqual(result2, [0, 9]) 

def test_with_multiple_static_shapes(self):
    def fn(elems):
      input_tensor, scalar_index_tensor = elems
      return tf.reshape(tf.slice(input_tensor, scalar_index_tensor, [1]), [])

    input_tensor = tf.constant([[1, 2, 3], [4, 5, -1], [0, 6, 9]],
                               dtype=tf.float32)
    scalar_index_tensor = tf.constant([[0], [2], [1]], dtype=tf.int32)
    map_fn_output = shape_utils.static_or_dynamic_map_fn(
        fn, [input_tensor, scalar_index_tensor], dtype=tf.float32)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(all(['map' != op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result = sess.run(map_fn_output)
      self.assertAllEqual(result, [1, -1, 6]) 

def test_with_multiple_dynamic_shapes(self):
    def fn(elems):
      input_tensor, scalar_index_tensor = elems
      return tf.reshape(tf.slice(input_tensor, scalar_index_tensor, [1]), [])

    input_tensor = tf.placeholder(tf.float32, shape=(None, 3))
    scalar_index_tensor = tf.placeholder(tf.int32, shape=(None, 1))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(
        fn, [input_tensor, scalar_index_tensor], dtype=tf.float32)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2, 3], [4, 5, -1], [0, 6, 9]],
              scalar_index_tensor: [[0], [2], [1]],
          })
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1, 0], [3, 9, 30]],
              scalar_index_tensor: [[1], [0]]
          })
      self.assertAllEqual(result1, [1, -1, 6])
      self.assertAllEqual(result2, [1, 3]) 

def test_with_static_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.constant([[1, 2], [3, 1], [0, 4]], dtype=tf.float32)
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(all(['map' != op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result = sess.run(map_fn_output)
      self.assertAllEqual(result, [3, 4, 4]) 

def test_with_static_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.constant([[1, 2], [3, 1], [0, 4]], dtype=tf.float32)
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(all(['map' != op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result = sess.run(map_fn_output)
      self.assertAllEqual(result, [3, 4, 4]) 

def test_with_multiple_dynamic_shapes(self):
    def fn(elems):
      input_tensor, scalar_index_tensor = elems
      return tf.reshape(tf.slice(input_tensor, scalar_index_tensor, [1]), [])

    input_tensor = tf.placeholder(tf.float32, shape=(None, 3))
    scalar_index_tensor = tf.placeholder(tf.int32, shape=(None, 1))
    map_fn_output = shape_utils.static_or_dynamic_map_fn(
        fn, [input_tensor, scalar_index_tensor], dtype=tf.float32)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(any(['map' == op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result1 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[1, 2, 3], [4, 5, -1], [0, 6, 9]],
              scalar_index_tensor: [[0], [2], [1]],
          })
      result2 = sess.run(
          map_fn_output, feed_dict={
              input_tensor: [[-1, 1, 0], [3, 9, 30]],
              scalar_index_tensor: [[1], [0]]
          })
      self.assertAllEqual(result1, [1, -1, 6])
      self.assertAllEqual(result2, [1, 3]) 

def test_with_static_shape(self):
    def fn(input_tensor):
      return tf.reduce_sum(input_tensor)
    input_tensor = tf.constant([[1, 2], [3, 1], [0, 4]], dtype=tf.float32)
    map_fn_output = shape_utils.static_or_dynamic_map_fn(fn, input_tensor)

    op_names = [op.name for op in tf.get_default_graph().get_operations()]
    self.assertTrue(all(['map' != op_name[:3] for op_name in op_names]))

    with self.test_session() as sess:
      result = sess.run(map_fn_output)
      self.assertAllEqual(result, [3, 4, 4]) 

def preprocess(self, inputs):
    """Feature-extractor specific preprocessing.

    See base class.

    For Faster R-CNN, we perform image resizing in the base class --- each
    class subclassing FasterRCNNMetaArch is responsible for any additional
    preprocessing (e.g., scaling pixel values to be in [-1, 1]).

    Args:
      inputs: a [batch, height_in, width_in, channels] float tensor representing
        a batch of images with values between 0 and 255.0.

    Returns:
      preprocessed_inputs: a [batch, height_out, width_out, channels] float
        tensor representing a batch of images.
      true_image_shapes: int32 tensor of shape [batch, 3] where each row is
        of the form [height, width, channels] indicating the shapes
        of true images in the resized images, as resized images can be padded
        with zeros.
    Raises:
      ValueError: if inputs tensor does not have type tf.float32
    """
    if inputs.dtype is not tf.float32:
      raise ValueError('`preprocess` expects a tf.float32 tensor')
    with tf.name_scope('Preprocessor'):
      outputs = shape_utils.static_or_dynamic_map_fn(
          self._image_resizer_fn,
          elems=inputs,
          dtype=[tf.float32, tf.int32],
          parallel_iterations=self._parallel_iterations)
      resized_inputs = outputs[0]
      true_image_shapes = outputs[1]
      return (self._feature_extractor.preprocess(resized_inputs),
              true_image_shapes) 

def normalized_to_image_coordinates(normalized_boxes, image_shape,
                                    parallel_iterations=32):
  """Converts a batch of boxes from normal to image coordinates.

  Args:
    normalized_boxes: a float32 tensor of shape [None, num_boxes, 4] in
      normalized coordinates.
    image_shape: a float32 tensor of shape [4] containing the image shape.
    parallel_iterations: parallelism for the map_fn op.

  Returns:
    absolute_boxes: a float32 tensor of shape [None, num_boxes, 4] containg the
      boxes in image coordinates.
  """
  def _to_absolute_coordinates(normalized_boxes):
    return box_list_ops.to_absolute_coordinates(
        box_list.BoxList(normalized_boxes),
        image_shape[1], image_shape[2], check_range=False).get()

  absolute_boxes = shape_utils.static_or_dynamic_map_fn(
      _to_absolute_coordinates,
      elems=(normalized_boxes),
      dtype=tf.float32,
      parallel_iterations=parallel_iterations,
      back_prop=True)
  return absolute_boxes 

def normalized_to_image_coordinates(normalized_boxes, image_shape,
                                    parallel_iterations=32):
  """Converts a batch of boxes from normal to image coordinates.

  Args:
    normalized_boxes: a float32 tensor of shape [None, num_boxes, 4] in
      normalized coordinates.
    image_shape: a float32 tensor of shape [4] containing the image shape.
    parallel_iterations: parallelism for the map_fn op.

  Returns:
    absolute_boxes: a float32 tensor of shape [None, num_boxes, 4] containing
      the boxes in image coordinates.
  """
  x_scale = tf.cast(image_shape[2], tf.float32)
  y_scale = tf.cast(image_shape[1], tf.float32)
  def _to_absolute_coordinates(normalized_boxes):
    y_min, x_min, y_max, x_max = tf.split(
        value=normalized_boxes, num_or_size_splits=4, axis=1)
    y_min = y_scale * y_min
    y_max = y_scale * y_max
    x_min = x_scale * x_min
    x_max = x_scale * x_max
    scaled_boxes = tf.concat([y_min, x_min, y_max, x_max], 1)
    return scaled_boxes

  absolute_boxes = shape_utils.static_or_dynamic_map_fn(
      _to_absolute_coordinates,
      elems=(normalized_boxes),
      dtype=tf.float32,
      parallel_iterations=parallel_iterations,
      back_prop=True)
  return absolute_boxes 

def normalized_to_image_coordinates(normalized_boxes, image_shape,
                                    parallel_iterations=32):
  """Converts a batch of boxes from normal to image coordinates.

  Args:
    normalized_boxes: a float32 tensor of shape [None, num_boxes, 4] in
      normalized coordinates.
    image_shape: a float32 tensor of shape [4] containing the image shape.
    parallel_iterations: parallelism for the map_fn op.

  Returns:
    absolute_boxes: a float32 tensor of shape [None, num_boxes, 4] containg the
      boxes in image coordinates.
  """
  def _to_absolute_coordinates(normalized_boxes):
    return box_list_ops.to_absolute_coordinates(
        box_list.BoxList(normalized_boxes),
        image_shape[1], image_shape[2], check_range=False).get()

  absolute_boxes = shape_utils.static_or_dynamic_map_fn(
      _to_absolute_coordinates,
      elems=(normalized_boxes),
      dtype=tf.float32,
      parallel_iterations=parallel_iterations,
      back_prop=True)
  return absolute_boxes 

def normalized_to_image_coordinates(normalized_boxes, image_shape,
                                    parallel_iterations=32):
    """Converts a batch of boxes from normal to image coordinates.

    Args:
      normalized_boxes: a float32 tensor of shape [None, num_boxes, 4] in
        normalized coordinates.
      image_shape: a float32 tensor of shape [4] containing the image shape.
      parallel_iterations: parallelism for the map_fn op.

    Returns:
      absolute_boxes: a float32 tensor of shape [None, num_boxes, 4] containg the
        boxes in image coordinates.
    """
    def _to_absolute_coordinates(normalized_boxes):
        return box_list_ops.to_absolute_coordinates(
            box_list.BoxList(normalized_boxes),
            image_shape[1], image_shape[2], check_range=False).get()

    absolute_boxes = shape_utils.static_or_dynamic_map_fn(
        _to_absolute_coordinates,
        elems=(normalized_boxes),
        dtype=tf.float32,
        parallel_iterations=parallel_iterations,
        back_prop=True)
    return absolute_boxes 

def preprocess(self, inputs):
    """Feature-extractor specific preprocessing.

    SSD meta architecture uses a default clip_window of [0, 0, 1, 1] during
    post-processing. On calling `preprocess` method, clip_window gets updated
    based on `true_image_shapes` returned by `image_resizer_fn`.

    Args:
      inputs: a [batch, height_in, width_in, channels] float tensor representing
        a batch of images with values between 0 and 255.0.

    Returns:
      preprocessed_inputs: a [batch, height_out, width_out, channels] float
        tensor representing a batch of images.
      true_image_shapes: int32 tensor of shape [batch, 3] where each row is
        of the form [height, width, channels] indicating the shapes
        of true images in the resized images, as resized images can be padded
        with zeros.

    Raises:
      ValueError: if inputs tensor does not have type tf.float32
    """
    if inputs.dtype is not tf.float32:
      raise ValueError('`preprocess` expects a tf.float32 tensor')
    with tf.name_scope('Preprocessor'):
      # TODO(jonathanhuang): revisit whether to always use batch size as
      # the number of parallel iterations vs allow for dynamic batching.
      outputs = shape_utils.static_or_dynamic_map_fn(
          self._image_resizer_fn,
          elems=inputs,
          dtype=[tf.float32, tf.int32])
      resized_inputs = outputs[0]
      true_image_shapes = outputs[1]

      return (self._feature_extractor.preprocess(resized_inputs),
              true_image_shapes)