code: def normalize(im, mean, std):
      im = im.astype(np.float32, copy=False) / 255.0
      im -= mean
      im /= std
      return im
  
imports: import cv2
  import numpy
  from PIL import Image, ImageEnhance
  from scipy.ndimage import distance_transform_edt
label_desc: Use image node_id 3 for calling a global function with example usage: normalize(im, mean, std) and returns: im