code: def forward(self, x):
      x = self.stn_convnet(x)
      batch_size, _, h, w = x.shape
      x = paddle.reshape(x, shape=(batch_size, -1))
      img_feat = self.stn_fc1(x)
      x = self.stn_fc2(0.1 * img_feat)
      if self.activation == "sigmoid":
          x = F.sigmoid(x)
      x = paddle.reshape(x, shape=[-1, self.num_ctrlpoints, 2])
      return img_feat, x
  
file_path: PaddleOCR/ppocr/modeling/transforms/stn.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import math
  import paddle
  from paddle import nn, ParamAttr
  from paddle.nn import functional
  import numpy
  from .tps_spatial_transformer import TPSSpatialTransformer
label_desc: Use image node_id 3 for calling the STN obj's underlying member method code with example usage: obj.forward(x) and returns: img_feat,  x