diff --git a/DPI/utils.py b/DPI/utils.py
index 83e9b9d..3790104 100644
--- a/DPI/utils.py
+++ b/DPI/utils.py
@@ -200,6 +200,10 @@ def make_env(args):
         )
     return env
 
+def preprocess_obs(obs):
+    obs = obs/255.0 - 0.5
+    return obs
+
 def soft_update_params(net, target_net, tau):
     for param, target_param in zip(net.parameters(), target_net.parameters()):
         target_param.data.copy_(
@@ -301,4 +305,4 @@ class FreezeParameters:
 
     def __exit__(self, exc_type, exc_val, exc_tb):
         for i, param in enumerate(get_parameters(self.modules)):
-            param.requires_grad = self.param_states[i]  
\ No newline at end of file
+            param.requires_grad = self.param_states[i]
\ No newline at end of file