code: def get_normal_map(img):
      img = img.astype(np.float32)
      img = img / 255.0
      img = -img + 1
      img[img < 0] = 0
      img[img > 1] = 1
      return img
  
imports: import numpy
  import cv2
  from scipy import ndimage
label_desc: Use image node_id 1 for calling a global function with example usage: get_normal_map(img) and returns: img