code: def create_input(self, t_input=None, forget_xy_shape=True):
      
      if t_input is None:
        t_input = tf.placeholder(tf.float32, self.image_shape)
      t_prep_input = t_input
      if len(t_prep_input.shape) == 3:
        t_prep_input = tf.expand_dims(t_prep_input, 0)
      if forget_xy_shape:
        t_prep_input = model_util.forget_xy(t_prep_input)
      if hasattr(self, "is_BGR") and self.is_BGR is True:
        t_prep_input = tf.reverse(t_prep_input, [-1])
      lo, hi = self.image_value_range
      t_prep_input = lo + t_prep_input * (hi - lo)
      return t_input, t_prep_input
docs: Create input tensor.