diff --git a/ppocr/modeling/stns/tps.py b/ppocr/modeling/stns/tps.py
old mode 100755
new mode 100644
index 24c6448d..18d0225d
--- a/ppocr/modeling/stns/tps.py
+++ b/ppocr/modeling/stns/tps.py
@@ -70,6 +70,13 @@ class LocalizationNetwork(object):
         return initial_bias
 
     def __call__(self, image):
+        """
+        Estimating parameters of geometric transformation
+        Args:
+            image: input
+        Return: 
+            batch_C_prime: the matrix of the geometric transformation
+        """
         F = self.F
         loc_lr = self.loc_lr
         if self.model_name == "large":
@@ -215,6 +222,14 @@ class GridGenerator(object):
         return batch_C_ex_part_tensor
 
     def __call__(self, batch_C_prime, I_r_size):
+        """
+        Generate the grid for the grid_sampler.
+        Args:
+            batch_C_prime: the matrix of the geometric transformation
+            I_r_size: the shape of the input image
+        Return: 
+            batch_P_prime: the grid for the grid_sampler 
+        """
         C = self.build_C()
         P = self.build_P(I_r_size)
         inv_delta_C = self.build_inv_delta_C(C).astype('float32')