code: def imread(
      img_or_path, flag="color", channel_order="bgr", backend=None
  ):
      """Read an image.
  
      Args:
          img_or_path (ndarray or str or Path): Either a numpy array or str or
              pathlib.Path. If it is a numpy array (loaded image), then
              it will be returned as is.
          flag (str): Flags specifying the color type of a loaded image,
              candidates are `color`, `grayscale`, `unchanged`,
              `color_ignore_orientation` and `grayscale_ignore_orientation`.
              By default, `cv2` and `pillow` backend would rotate the image
              according to its EXIF info unless called with `unchanged` or
              `*_ignore_orientation` flags. `turbojpeg` and `tifffile` backend
              always ignore image's EXIF info regardless of the flag.
              The `turbojpeg` backend only supports `color` and `grayscale`.
          channel_order (str): Order of channel, candidates are `bgr` and `rgb`.
          backend (str | None): The image decoding backend type. Options are
              `cv2`, `pillow`, `turbojpeg`, `tifffile`, `None`.
              If backend is None, the global imread_backend specified by
              ``mmcv.use_backend()`` will be used. Default: None.
  
      Returns:
          ndarray: Loaded image array.
      """
  
      if backend is None:
          backend = imread_backend
      if backend not in supported_backends:
          raise ValueError(
              f"backend: {backend} is not supported. Supported "
              "backends are 'cv2', 'turbojpeg', 'pillow'"
          )
      if isinstance(img_or_path, Path):
          img_or_path = str(img_or_path)
  
      if isinstance(img_or_path, np.ndarray):
          return img_or_path
      elif is_str(img_or_path):
          check_file_exist(
              img_or_path, f"img file does not exist: {img_or_path}"
          )
          if backend == "turbojpeg":
              with open(img_or_path, "rb") as in_file:
                  img = jpeg.decode(
                      in_file.read(), _jpegflag(flag, channel_order)
                  )
                  if img.shape[-1] == 1:
                      img = img[:, :, 0]
              return img
          elif backend == "pillow":
              img = Image.open(img_or_path)
              img = _pillow2array(img, flag, channel_order)
              return img
          elif backend == "tifffile":
              img = tifffile.imread(img_or_path)
              return img
          else:
              flag = imread_flags[flag] if is_str(flag) else flag
              img = cv2.imread(img_or_path, flag)
              if flag == IMREAD_COLOR and channel_order == "rgb":
                  cv2.cvtColor(img, cv2.COLOR_BGR2RGB, img)
              return img
      else:
          raise TypeError(
              '"img" must be a numpy array or a str or '
              "a pathlib.Path object"
          )
  
file_path: lavis/lavis/common/annotator/uniformer/mmcv/image/io.py
imports: import io
  import os.path
  from pathlib import Path
  import cv2
  import numpy
  from cv2 import IMREAD_COLOR, IMREAD_GRAYSCALE, IMREAD_IGNORE_ORIENTATION, IMREAD_UNCHANGED
  from annotator.uniformer.mmcv.utils import check_file_exist, is_str, mkdir_or_exist
label_desc: Use image node_id 4 for calling a global function with example usage: imread(img_or_path, flag, channel_order, backend) and returns: img_or_path, img, img, img, img