diff --git a/modules/util/util.py b/modules/util/util.py
index 6d7871a77963929206c627a78036f3028a841dc6..bc6ab86df29dc12412b9ff81906d2166ed673a26 100644
--- a/modules/util/util.py
+++ b/modules/util/util.py
@@ -413,7 +413,11 @@ def scale(data, param, mean_std_dict):
     shape = data.shape
     data = data.flatten()
 
-    mean, std, lo, hi = mean_std_dict.get(param)
+    if mean_std_dict is None:
+        lo = np.nanmin(data)
+        hi = np.nanmax(data)
+
+    _, _, lo, hi = mean_std_dict.get(param)
 
     data -= lo
     data /= (hi - lo)