class_docstr: Normlize image by given mean and std.
      
code: def __call__(self, sample):
      sample["image"] = (sample["image"] - self.__mean) / self.__std
  
      return sample
  
file_path: PaddleHub/modules/image/depth_estimation/MiDaS_Small/transforms.py
imports: import numpy
  import cv2
label_desc: Use image node_id 2 for calling the NormalizeImage obj's underlying member method code with example usage: obj.__call__(sample) and returns: sample