code: def _get_thumbnail_src_from_file(dir_path, image_file, force_no_processing=False):
      
      # If we've specified to force no processing, just return the image filename
      if force_no_processing:
          if image_file.endswith('tif') or image_file.endswith('tiff'):
              return UNSUPPORTED_IMAGE_TYPE_DATA
          return image_file
      # First try to get a thumbnail image
      img = _get_thumbnail_image_from_file(dir_path, image_file)
      return _get_src_from_image(img, image_file)
docs: Get base-64 encoded data as a string for the given image file's thumbnail,
      for use directly in HTML <img> tags, or a path to the original if image
      scaling is not supported.
      @param {String} dir_path - The directory containing the image file
      @param {String} image_file - The filename of the image file within dir_path
      @param {Boolean=False} force_no_processing - If True, do not attempt to
          actually process a thumbnail, PIL image or anything. Simply return the
          image filename as src.
      @return {String} The base-64 encoded image data string, or path to the file
          itself if not supported.