diff --git a/modules/util/viirs_l1b_l2.py b/modules/util/viirs_l1b_l2.py
index 7c88d533a5b659a52d8da40d7deef49cb1b15fd2..3b80a582c8198c9ec286b78f2d8a8c90944c50ca 100644
--- a/modules/util/viirs_l1b_l2.py
+++ b/modules/util/viirs_l1b_l2.py
@@ -217,6 +217,8 @@ def run_all(directory, out_directory, day_night='ANY', start=10):
     print('** total_num_train_samples, total_num_valid_samples: ', total_num_train_samples, total_num_valid_samples)
 
 
+#  tile_width: Must be even!
+#  kernel_size: Must be odd!
 def run(data_h5f, param_s, train_tiles, valid_tiles, num_keep_x_tiles=8, tile_width=64, kernel_size=9, day_night='ANY'):
 
     border = int((kernel_size - 1)/2)
@@ -224,7 +226,7 @@ def run(data_h5f, param_s, train_tiles, valid_tiles, num_keep_x_tiles=8, tile_wi
     param_name = param_s[0]
 
     num_lines = data_h5f[param_name].shape[0]
-    num_pixels = data_h5f[param_name].shape[1]
+    num_pixels = data_h5f[param_name].shape[1]  # Must be even
 
     if day_night != 'BOTH':
         solzen = get_grid_values(data_h5f, solzen_name, 0, 0, None, num_lines, num_pixels)