Pyqtgraph HistogramLUTWidget getLookupTable error.

testcase.py

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)

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)


w.gradient.colorMap().getLookupTable(mode='qcolor', alpha=True)  # Works
w.gradient.getLookupTable(512)  # Works but does not return QColors
w.gradient.colorMap().getLookupTable(mode='qcolor', alpha=False)  # Fails
w.gradient.colorMap().getLookupTable(mode='qcolor')  # Fails


## 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_()