class_docstr: Apply Normalization to Image Pixels on GPU
      
code: def __call__(self, img):
      if torch.max(img) > 1 and self.mean.max() <= 1:
          img.div_(255.0)
      return img.sub_(self.mean).div_(self.std)
  
imports: from torch.utils.data import Dataset
  from torchvision.datasets.utils import download_url
  from PIL import Image
  import torch
  import numpy
  import random
  import decord
  from decord import VideoReader
  import json
  import os
  from data.utils import pre_caption
label_desc: Use image node_id 2 for calling the ImageNorm obj's underlying member method code with example usage: obj.__call__(img) and returns: img