separate out tensorflow install

README.md

@@ -13,7 +13,18 @@ Download the model data
 sh download_model.sh 117M
 ```
 
-Install python packages:
+The remaining steps can optionally be done in a virtual environment using tools such as `virtualenv` or `conda`.
+
+Install tensorflow 1.12 (with GPU support, if you have a GPU and want everything to run faster)
+```
+pip3 install tensorflow==1.12.0
+```
+or
+```
+pip3 install tensorflow-gpu==1.12.0
+```
+
+Install other python packages:
 ```
 pip3 install -r requirements.txt
 ```

requirements.txt

@@ -1,3 +1,2 @@
 fire>=0.1.3
-tensorflow>=1.12
 regex==2017.4.5