If all data pixel are on NaN, then assign a value of 0.0 for each pixel.

AFM_thumbs/Linalg.py

@@ -198,6 +198,11 @@ def check_image_properties(data, data_file):
 
         list_nans = np.where(np.isnan(data))[0]
         data_clean = np.delete(data, list_nans)
+
+        # If all pixels are on NaN, then put the mean value onto 0.0.
+        if len(list_nans) == len(data):
+            data_mean = 0.0
+        else:
             data_mean = np.mean(data_clean)
 
         for nan in list_nans: