use shape utils for assertion in feature extractor.

PiperOrigin-RevId: 192147130

research/object_detection/models/faster_rcnn_mobilenet_v1_feature_extractor.py

@@ -17,6 +17,7 @@
 import tensorflow as tf
 
 from object_detection.meta_architectures import faster_rcnn_meta_arch
+from object_detection.utils import shape_utils
 from nets import mobilenet_v1
 
 slim = tf.contrib.slim
@@ -112,12 +113,9 @@ class FasterRCNNMobilenetV1FeatureExtractor(
     """
 
     preprocessed_inputs.get_shape().assert_has_rank(4)
-    shape_assert = tf.Assert(
-        tf.logical_and(tf.greater_equal(tf.shape(preprocessed_inputs)[1], 33),
-                       tf.greater_equal(tf.shape(preprocessed_inputs)[2], 33)),
-        ['image size must at least be 33 in both height and width.'])
+    preprocessed_inputs = shape_utils.check_min_image_dim(
+        min_dim=33, image_tensor=preprocessed_inputs)
 
-    with tf.control_dependencies([shape_assert]):
     with slim.arg_scope(
         mobilenet_v1.mobilenet_v1_arg_scope(
             is_training=self._train_batch_norm,