diff --git a/bob/bio/base/test/dummy/preprocessor.py b/bob/bio/base/test/dummy/preprocessor.py
index 89376c31d59dd215b321153a6c56dbda75f32e0e..506f0ef881df79e09c12c028174222bcb6f189b9 100644
--- a/bob/bio/base/test/dummy/preprocessor.py
+++ b/bob/bio/base/test/dummy/preprocessor.py
@@ -16,5 +16,14 @@ class DummyPreprocessor (Preprocessor):
       
     return data
 
-
 preprocessor = DummyPreprocessor()
+
+
+class DummyPreprocessorMetadata (DummyPreprocessor):
+
+  def __call__(self, data, annotation, metadata=None):
+    """Does nothing, simply converts the data type of the data, ignoring any annotation."""
+    assert metadata is not None    
+    return super(DummyPreprocessorMetadata, self).__call__(data, annotation)
+
+preprocessor_metadata = DummyPreprocessorMetadata()
diff --git a/bob/bio/base/test/test_scripts.py b/bob/bio/base/test/test_scripts.py
index fcf369b7341ab464803ec3013e152ab2238ebd39..609487982bc24ada63ad7fe37a425f75f2965496 100644
--- a/bob/bio/base/test/test_scripts.py
+++ b/bob/bio/base/test/test_scripts.py
@@ -148,7 +148,7 @@ def test_verify_resources_metadata():
   # define dummy parameters
   parameters = [
       '-d', 'dummy',
-      '-p', 'dummy',
+      '-p', 'dummy_metadata',
       '-e', 'dummy_metadata',
       '-a', 'dummy',
       '--zt-norm',
diff --git a/bob/bio/base/tools/preprocessor.py b/bob/bio/base/tools/preprocessor.py
index 83eafab8953940e3a668c398e6b4e6166fa5cccf..b4140dfac86ea14b8f88d51ee54220f307c40020 100644
--- a/bob/bio/base/tools/preprocessor.py
+++ b/bob/bio/base/tools/preprocessor.py
@@ -2,6 +2,7 @@ import bob.io.base
 import os
 
 import logging
+import inspect
 logger = logging.getLogger("bob.bio.base")
 
 from .FileSelector import FileSelector
@@ -45,6 +46,7 @@ def preprocess(preprocessor, groups = None, indices = None, allow_missing_files
   data_files = fs.original_data_list(groups=groups)
   original_directory, original_extension = fs.original_directory_and_extension()
   preprocessed_data_files = fs.preprocessed_data_list(groups=groups)
+  metadata = fs.original_data_list(groups=groups)
 
   # select a subset of keys to iterate
   if indices is not None:
@@ -58,7 +60,7 @@ def preprocess(preprocessor, groups = None, indices = None, allow_missing_files
   # read annotation files
   annotation_list = fs.annotation_list(groups=groups)
 
-  # iterate over the selected files
+  # iterate over the selected files  
   for i in index_range:
     preprocessed_data_file = preprocessed_data_files[i]
     file_object = data_files[i]
@@ -78,7 +80,11 @@ def preprocess(preprocessor, groups = None, indices = None, allow_missing_files
       annotations = fs.get_annotations(annotation_list[i])
 
       # call the preprocessor
-      preprocessed_data = preprocessor(data, annotations)
+      if "metadata" in inspect.getargspec(preprocessor.__call__).args:
+        preprocessed_data = preprocessor(data, annotations, metadata=metadata[i])
+      else:
+        preprocessed_data = preprocessor(data, annotations)
+
       if preprocessed_data is None:
         if allow_missing_files:
           logger.debug("... Processing original data file '%s' was not successful", file_name)
@@ -90,8 +96,7 @@ def preprocess(preprocessor, groups = None, indices = None, allow_missing_files
       preprocessor.write_data(preprocessed_data, preprocessed_data_file)
 
     else:
-      logger.debug("... Skipping original data file '%s' since preprocessed data '%s' exists", file_name, preprocessed_data_file)
-
+      logger.debug("... Skipping original data file '%s' since preprocessed data '%s' exists", file_name, preprocessed_data_file)    
 
 
 def read_preprocessed_data(file_names, preprocessor, split_by_client = False, allow_missing_files = False):
diff --git a/setup.py b/setup.py
index 91b66c18d425c6fd5e058cf60e3f795cf3633315..4ddf3c9394e559ae8d1da7603ce6569a9c0d320a 100644
--- a/setup.py
+++ b/setup.py
@@ -95,6 +95,7 @@ setup(
       'bob.bio.preprocessor': [
         'dummy             = bob.bio.base.test.dummy.preprocessor:preprocessor', # for test purposes only
         'filename          = bob.bio.base.config.preprocessor.filename:preprocessor',
+        'dummy_metadata    = bob.bio.base.test.dummy.preprocessor:preprocessor_metadata',
       ],
 
       'bob.bio.extractor': [