code: def gray2bgr(img):
      """Convert a grayscale image to BGR image.
  
      Args:
          img (ndarray): The input image.
  
      Returns:
          ndarray: The converted BGR image.
      """
      img = img[..., None] if img.ndim == 2 else img
      out_img = cv2.cvtColor(img, cv2.COLOR_GRAY2BGR)
      return out_img
  
file_path: lavis/lavis/common/annotator/uniformer/mmcv/image/colorspace.py
imports: import cv2
  import numpy
label_desc: Use image node_id 4 for calling a global function with example usage: gray2bgr(img) and returns: out_img