Merge pull request #1471 from Trusted-AI/development_issue_1468

Replace x with x_preprocessed in PyTorchClassifier.get_activations

Author: beat-buesser

art/estimators/classification/pytorch.py

@@ -834,7 +834,11 @@ def get_activations(
         self._model.eval()
 
         # Apply defences
-        x_preprocessed, _ = self._apply_preprocessing(x=x, y=None, fit=False)
+        if framework:
+            no_grad = False
+        else:
+            no_grad = True
+        x_preprocessed, _ = self._apply_preprocessing(x=x, y=None, fit=False, no_grad=no_grad)
 
         # Get index of the extracted layer
         if isinstance(layer, six.string_types):
@@ -849,9 +853,9 @@ def get_activations(
             raise TypeError("Layer must be of type str or int")
 
         if framework:
-            if isinstance(x, torch.Tensor):
-                return self._model(x)[layer_index]
-            return self._model(torch.from_numpy(x).to(self._device))[layer_index]
+            if isinstance(x_preprocessed, torch.Tensor):
+                return self._model(x_preprocessed)[layer_index]
+            return self._model(torch.from_numpy(x_preprocessed).to(self._device))[layer_index]
 
         # Run prediction with batch processing
         results = []