How can I use the tensorflow .pb file?

Question

I have a Tensorflow file AlexNet.pb I am trying to load it then classify an image that I have. I have searched for hours but I still cant find a way to load it then classify an image. Is it so obvious and that I am just so stupid because no one seems to have a simple example of loading and running the .pb file.

Answer 1

It depends on how the protobuf file has been created.

If the .pb file is the result of:

    # Create a builder to export the model
    builder = tf.saved_model.builder.SavedModelBuilder("export")
    # Tag the model in order to be capable of restoring it specifying the tag set
    builder.add_meta_graph_and_variables(sess, ["tag"])
    builder.save()

You have to know how that model has been tagged and use the tf.saved_model.loader.load method to load the saved graph in the current, empty, graph.

If the model instead has been frozen you have to load the binary file in memory manually:

with tf.gfile.GFile(frozen_graph_filename, "rb") as f:
    graph_def = tf.GraphDef()
    graph_def.ParseFromString(f.read())

graph = tf.get_default_graph()
tf.import_graph_def(graph_def, name="prefix")

In both cases, you have to know the name of the input tensor and the name of the node you want to execute:

If, for example, your input tensor is a placeholder named batch_ and the node you want to execute is the node named dense/BiasAdd:0 you have to

    batch = graph.get_tensor_by_name('batch:0')
    prediction = restored_graph.get_tensor_by_name('dense/BiasAdd:0')

    values = sess.run(prediction, feed_dict={
        batch: your_input_batch,
    })