old_contents: # -*- coding: utf-8 -*-
  """
  Use a HistogramLUTWidget to control the contrast / coloration of an image.
  """
  
  ## Add path to library (just for examples; you do not need this)                                                                           
  import initExample
  
  import numpy as np
  from pyqtgraph.Qt import QtGui, QtCore
  import pyqtgraph as pg
  
  
  app = QtGui.QApplication([])
  win = QtGui.QMainWindow()
  win.resize(800,600)
  win.show()
  win.setWindowTitle('pyqtgraph example: Histogram LUT')
  
  cw = QtGui.QWidget()
  win.setCentralWidget(cw)
  
  l = QtGui.QGridLayout()
  cw.setLayout(l)
  l.setSpacing(0)
  
  v = pg.GraphicsView()
  vb = pg.ViewBox()
  vb.setAspectLocked()
  v.setCentralItem(vb)
  l.addWidget(v, 0, 0)
  
  w = pg.HistogramLUTWidget()
  l.addWidget(w, 0, 1)
  
  data = pg.gaussianFilter(np.random.normal(size=(256, 256)), (20, 20))
  for i in range(32):
      for j in range(32):
          data[i*8, j*8] += .1
  img = pg.ImageItem(data)
  #data2 = np.zeros((2,) + data.shape + (2,))
  #data2[0,:,:,0] = data  ## make non-contiguous array for testing purposes
  #img = pg.ImageItem(data2[0,:,:,0])
  vb.addItem(img)
  vb.autoRange()
  
  w.setImageItem(img)
  
  
  ## Start Qt event loop unless running in interactive mode.
  if __name__ == '__main__':
      import sys
      if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
          QtGui.QApplication.instance().exec_()
  
new_contents: # -*- coding: utf-8 -*-
  """
  Use a HistogramLUTWidget to control the contrast / coloration of an image.
  """
  
  ## Add path to library (just for examples; you do not need this)                                                                           
  import initExample
  
  import numpy as np
  from pyqtgraph.Qt import QtGui, QtCore
  import pyqtgraph as pg
  
  
  app = QtGui.QApplication([])
  win = QtGui.QMainWindow()
  win.resize(800,600)
  win.show()
  win.setWindowTitle('pyqtgraph example: Histogram LUT')
  
  cw = QtGui.QWidget()
  win.setCentralWidget(cw)
  
  l = QtGui.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()
  l.addWidget(w, 0, 1)
  
  monoRadio = QtGui.QRadioButton('mono')
  rgbaRadio = QtGui.QRadioButton('rgba')
  l.addWidget(monoRadio, 1, 1)
  l.addWidget(rgbaRadio, 2, 1)
  monoRadio.setChecked(True)
  
  def setLevelMode():
      mode = 'mono' if monoRadio.isChecked() else 'rgba'
      w.setLevelMode(mode)
  monoRadio.toggled.connect(setLevelMode)
  
  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] += .1
  img = pg.ImageItem(data)
  vb.addItem(img)
  vb.autoRange()
  
  w.setImageItem(img)
  
  
  ## Start Qt event loop unless running in interactive mode.
  if __name__ == '__main__':
      import sys
      if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
          QtGui.QApplication.instance().exec_()
  
subject: Update histogramlut example to allow rgb mode