how to freeze an imagenet classifier in tensorflow?

I have used Tensorflow to create an ImageNet model. The following files are created:

-{DIR}bottleneck
-{DIR}retrain_logs
-checkpoint
-output_graph.pb
-output_labels.txt
-_retrain_checkpoint.data-00000-of-00001
-_retrain_checkpoint.index
-_retrain_checkpoint.meta

I'm trying to use freeze_graph in tensorflow 1.8 Using Python 3.5.

python freeze_graph.py --input_graph output_graph.pb   --output_graph 
graph_frozen.pb --output_node_name=output --input_binary true --checkpoint

but what do i use as --checkpoint for ImageNet?

Buzz