code: def testHistogramLUTWidget():
      pg.mkQApp()
  
      win = QtWidgets.QMainWindow()
      win.show()
  
      cw = QtWidgets.QWidget()
      win.setCentralWidget(cw)
  
      l = QtWidgets.QGridLayout()
      cw.setLayout(l)
      l.setSpacing(0)
  
      v = pg.GraphicsView()
      vb = pg.ViewBox()
      vb.setAspectLocked()
      v.setCentralItem(vb)
      l.addWidget(v, 0, 0, 3, 1)
  
      w = pg.HistogramLUTWidget(background="w")
      l.addWidget(w, 0, 1)
  
      data = pg.gaussianFilter(
          np.random.normal(size=(256, 256, 3)), (20, 20, 0)
      )
      for i in range(32):
          for j in range(32):
              data[i * 8, j * 8] += 0.1
      img = pg.ImageItem(data)
      vb.addItem(img)
      vb.autoRange()
  
      w.setImageItem(img)
  
      QtWidgets.QApplication.processEvents()
      win.close()
  
label_desc: Use image node_id 1 for calling a global function with example usage: testHistogramLUTWidget() without return types