class_docstr: DB pre-process for Test mode
class_docstr_tok: ["DB","pre-process","for","Test","mode"]
code: def normalize(self, im):
      img_mean = [0.485, 0.456, 0.406]
      img_std = [0.229, 0.224, 0.225]
      im = im.astype(np.float32, copy=False)
      im = im / 255
      im[:, :, 0] -= img_mean[0]
      im[:, :, 1] -= img_mean[1]
      im[:, :, 2] -= img_mean[2]
      im[:, :, 0] /= img_std[0]
      im[:, :, 1] /= img_std[1]
      im[:, :, 2] /= img_std[2]
      channel_swap = (2, 0, 1)
      im = im.transpose(channel_swap)
      return im
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import sys
  import cv2
  import numpy
  import pyclipper
  from PIL import ImageDraw
  from shapely.geometry import Polygon
label_desc: Use image node_id 4 for calling the DBProcessTest obj's underlying member method code with example usage: obj.normalize(im) and returns: im