class_docstr: Extract image feature using pretrained CNN network.
class_docstr_tok: ["Extract","image","feature","using","pretrained","CNN","network","."]
code: def _img_to_ascii(self, im):
      im.thumbnail((60, 40), Image.BICUBIC)
      im = im.convert("L")
      asc = []
      for y in range(0, im.size[1]):
          for x in range(0, im.size[0]):
              lum = 255 - im.getpixel((x, y))
              asc.append(_greyscale[lum * len(_greyscale) // 256])
          asc.append("\n")
      return "".join(asc)
  
imports: import parlai.core.build_data
  import parlai.utils.logging
  from parlai.utils.io import PathManager
  import os
  from PIL import Image
  import torch
  from zipfile import ZipFile
label_desc: Use image node_id 9 for calling the ImageLoader obj's underlying member method code with example usage: obj._img_to_ascii(im) and returns: str