Using inception-v3 checkpoint file in tensorflow

Question

In one of my project, I used a public pre-trained inception-v3 model available here : http://download.tensorflow.org/models/image/imagenet/inception-2015-12-05.tgz.

I only want to use last feature vector (output of pool_3/_reshape:0). By looking at script example classify_image.py, I can successfully pass an image throught the Deep DNN, extract the bottleneck tensor (bottleneck_tensor = sess.graph.get_tensor_by_name('pool_3/_reshape:0')) and use it for further purpose.

I recently saw that there were a more recent trained inception model. Checkpoint of training is available here : http://download.tensorflow.org/models/image/imagenet/inception-v3-2016-03-01.tar.gz.

I would like to use this new pretrained instead of the old one. However file format is different. The "old model" uses a graph def in ProtocolBuffer form (classify_image_graph_def.pb) that is easily reusable. The "new one" only provides a checkpoint format, and I'm struggling to insert it into my code.

Is there an easy way to convert a checkpoint file to a ProtocolBuffer file that could be then used to create a graph?

Answer 1

It seems you have to use freeze_graph.py: https://github.com/tensorflow/tensorflow/blob/master/tensorflow/python/tools/freeze_graph.py

The script converts checkpoint variables into Const ops in a standalone GraphDef file. This script is designed to take a GraphDef proto, a SaverDef proto, and a set of variable values stored in a checkpoint file, and output a GraphDef with all of the variable ops converted into const ops containing the values of the variables. It's useful to do this when we need to load a single file in C++, especially in environments like mobile or embedded where we may not have access to the RestoreTensor ops and file loading calls that they rely on.

An example of command-line usage is:

bazel build tensorflow/python/tools:freeze_graph && \
bazel-bin/tensorflow/python/tools/freeze_graph \
--input_graph=some_graph_def.pb \
--input_checkpoint=model.ckpt-8361242 \
--output_graph=/tmp/frozen_graph.pb --output_node_names=softmax