'Extracts second stage box classifier features.
Args:
proposal_feature_maps: A 4-D float tensor with shape
[batch_size * self.max_num_proposals, crop_height, crop_width, depth]
representing the feature map cropped to each proposal.
scope: A scope name.
Returns:
proposal_classifier_features: A 4-D float tensor with shape
[batch_size * self.max_num_proposals, height, width, depth]
representing box classifier features for each proposal.'

def extract_box_classifier_features(self, proposal_feature_maps, scope):

    with tf.variable_scope(scope, values=[proposal_feature_maps]):
        return self._extract_box_classifier_features(proposal_feature_maps, scope)
