diff --git a/bioimageio/core/proc_ops.py b/bioimageio/core/proc_ops.py
index b05d7c8b..96419b3e 100644
--- a/bioimageio/core/proc_ops.py
+++ b/bioimageio/core/proc_ops.py
@@ -73,6 +73,9 @@ def required_measures(self) -> Collection[Measure]:
     def get_output_shape(self, input_shape: PerAxis[int]) -> PerAxis[int]: ...
 
     def __call__(self, sample: Union[Sample, SampleBlock]) -> None:
+        if self.input not in sample.members:
+            return
+
         input_tensor = sample.members[self.input]
         output_tensor = self._apply(input_tensor, sample.stat)