# 5.1. Freeze a model

The trained neural network is extracted from a checkpoint and dumped into a protobuf(.pb) file. This process is called “freezing” a model. The idea and part of our code are from Morgan. To freeze a model, typically one does

\$ dp freeze -o graph.pb


in the folder where the model is trained. The output model is called graph.pb.

In multi-task mode, this process will output several models, each of which contains the common descriptor and one of the user-defined fitting nets in fitting_net_dict, let’s name it fitting_key, together frozen in graph_{fitting_key}.pb. Those frozen models are exactly the same as single-task output with fitting net fitting_key.