diff --git a/code/image_preprocessing.py b/code/image_preprocessing.py
index 5dadfec9e2d2137fa3cccf8bed56af562ca77e3f..266b43113d8a20c8e52a62ca5bd64fab052b6348 100755
--- a/code/image_preprocessing.py
+++ b/code/image_preprocessing.py
@@ -115,7 +115,7 @@ for ind_c,std_list_condition in enumerate(std_list):
 plt.show()    
     
 #Average intesity-spread across al image channels
-mean_std = sum(std_list)/len(std_list)
+mean_std = sum(std_list_flat)/len(std_list_flat)
 print('The average spread of an image channel is ' + str(round(mean_std)))
  
 #%% Correct intensities