diff --git a/pyclesperanto_prototype/_tier2/_maximum_of_touching_neighbors.py b/pyclesperanto_prototype/_tier2/_maximum_of_touching_neighbors.py
index ef08cb21..9725c634 100644
--- a/pyclesperanto_prototype/_tier2/_maximum_of_touching_neighbors.py
+++ b/pyclesperanto_prototype/_tier2/_maximum_of_touching_neighbors.py
@@ -3,7 +3,7 @@
 from .._tier0 import Image
 
 @plugin_function
-def maximum_of_touching_neighbors(values : Image, touch_matrix : Image, maximum_values_destination : Image):
+def maximum_of_touching_neighbors(values : Image, touch_matrix : Image, maximum_values_destination : Image = None):
     """Takes a touch matrix and a vector of values to determine the maximum 
     value among touching neighbors for every object. 
     
diff --git a/pyclesperanto_prototype/_tier2/_mean_of_touching_neighbors.py b/pyclesperanto_prototype/_tier2/_mean_of_touching_neighbors.py
index 7b4e6c35..b60a2afe 100644
--- a/pyclesperanto_prototype/_tier2/_mean_of_touching_neighbors.py
+++ b/pyclesperanto_prototype/_tier2/_mean_of_touching_neighbors.py
@@ -3,7 +3,7 @@
 from .._tier0 import Image
 
 @plugin_function
-def mean_of_touching_neighbors(values : Image, touch_matrix : Image, mean_values_destination : Image):
+def mean_of_touching_neighbors(values : Image, touch_matrix : Image, mean_values_destination : Image = None):
     """Takes a touch matrix and a vector of values to determine the mean value 
     among touching neighbors for every object. 
     
diff --git a/pyclesperanto_prototype/_tier2/_median_of_touching_neighbors.py b/pyclesperanto_prototype/_tier2/_median_of_touching_neighbors.py
index d2051289..a398e7c4 100644
--- a/pyclesperanto_prototype/_tier2/_median_of_touching_neighbors.py
+++ b/pyclesperanto_prototype/_tier2/_median_of_touching_neighbors.py
@@ -3,7 +3,7 @@
 from .._tier0 import Image
 
 @plugin_function
-def median_of_touching_neighbors(values : Image, touch_matrix : Image, median_values_destination : Image):
+def median_of_touching_neighbors(values : Image, touch_matrix : Image, median_values_destination : Image = None):
     """Takes a touch matrix and a vector of values to determine the median 
     value among touching neighbors for every object. 
     
diff --git a/pyclesperanto_prototype/_tier2/_minimum_of_touching_neighbors.py b/pyclesperanto_prototype/_tier2/_minimum_of_touching_neighbors.py
index 54a6b495..b8cdfb7e 100644
--- a/pyclesperanto_prototype/_tier2/_minimum_of_touching_neighbors.py
+++ b/pyclesperanto_prototype/_tier2/_minimum_of_touching_neighbors.py
@@ -3,7 +3,7 @@
 from .._tier0 import Image
 
 @plugin_function
-def minimum_of_touching_neighbors(values : Image, touch_matrix : Image, minimum_values_destination : Image):
+def minimum_of_touching_neighbors(values : Image, touch_matrix : Image, minimum_values_destination : Image = None):
     """Takes a touch matrix and a vector of values to determine the minimum 
     value among touching neighbors for every object. 
     
diff --git a/pyclesperanto_prototype/_tier2/_mode_of_touching_neighbors.py b/pyclesperanto_prototype/_tier2/_mode_of_touching_neighbors.py
index 0ba53e97..98345f7a 100644
--- a/pyclesperanto_prototype/_tier2/_mode_of_touching_neighbors.py
+++ b/pyclesperanto_prototype/_tier2/_mode_of_touching_neighbors.py
@@ -3,7 +3,7 @@
 from .._tier0 import Image
 
 @plugin_function
-def mode_of_touching_neighbors(src_values : Image, touch_matrix : Image, dst_values : Image):
+def mode_of_touching_neighbors(src_values : Image, touch_matrix : Image, dst_values : Image = None):
     """
 
     Parameters
diff --git a/pyclesperanto_prototype/_tier2/_standard_deviation_of_touching_neighbors.py b/pyclesperanto_prototype/_tier2/_standard_deviation_of_touching_neighbors.py
index 444658c5..620050f9 100644
--- a/pyclesperanto_prototype/_tier2/_standard_deviation_of_touching_neighbors.py
+++ b/pyclesperanto_prototype/_tier2/_standard_deviation_of_touching_neighbors.py
@@ -3,7 +3,7 @@
 from .._tier0 import Image
 
 @plugin_function
-def standard_deviation_of_touching_neighbors(values : Image, touch_matrix : Image, standard_deviation_values_destination : Image):
+def standard_deviation_of_touching_neighbors(values : Image, touch_matrix : Image, standard_deviation_values_destination : Image = None):
     """Takes a touch matrix and a vector of values to determine the standard 
     deviation value among touching neighbors for every object.