class_docstr: Convert color space from LAB to RGB.
class_docstr_tok: ["Convert","color","space","from","LAB","to","RGB","."]
docstr: Convert color space from LAB to XYZ.
  
  Args:
     img(np.ndarray): Original LAB image.
  
  Return:
      img(np.ndarray): Converted XYZ image.
code: def lab2xyz(self, lab: np.ndarray) -> np.ndarray:
      """
      Convert color space from LAB to XYZ.
  
      Args:
         img(np.ndarray): Original LAB image.
  
      Return:
          img(np.ndarray): Converted XYZ image.
      """
      y_int = (lab[:, 0, :, :] + 16.0) / 116.0
      x_int = (lab[:, 1, :, :] / 500.0) + y_int
      z_int = y_int - (lab[:, 2, :, :] / 200.0)
      z_int = np.maximum(z_int, 0)
      out = np.concatenate(
          (
              x_int[:, None, :, :],
              y_int[:, None, :, :],
              z_int[:, None, :, :],
          ),
          axis=1,
      )
      mask = (out > 0.2068966).astype(np.float32)
      np.seterr(invalid="ignore")
      out = (out**3.0) * mask + (out - 16.0 / 116.0) / 7.787 * (
          1 - mask
      )
      out = np.nan_to_num(out)
      sc = np.array((0.95047, 1.0, 1.08883))[None, :, None, None]
      out = out * sc
      return out
  
imports: import random
  from typing import Callable, Union, List, Tuple
  import cv2
  import PIL
  import numpy
  import paddlehub.vision.functional
label_desc: Use image node_id 3 for calling the LAB2RGB obj's underlying member method code with example usage: obj.lab2xyz(lab) and returns: out