Embedding matplotlib in pyqt4 using imshow

I am trying to do something very similar to this. The twist is that I want to use imshow instead of plot.

Relevant parts of code from above:

class MyMplCanvas(FigureCanvas):
    """Ultimately, this is a QWidget (as well as a FigureCanvasAgg, etc.)."""
    def __init__(self, parent=None, width=5, height=4, dpi=100):
        fig = Figure(figsize=(width, height), dpi=dpi)
        self.axes = fig.add_subplot(111)
        # We want the axes cleared every time plot() is called
        self.axes.hold(False)

        self.compute_initial_figure()

        #
        FigureCanvas.__init__(self, fig)
        self.setParent(parent)

        FigureCanvas.setSizePolicy(self,
                                   QtGui.QSizePolicy.Expanding,
                                   QtGui.QSizePolicy.Expanding)
        FigureCanvas.updateGeometry(self)

    def compute_initial_figure(self):
        pass

class MyDynamicMplCanvas(MyMplCanvas):
    """A canvas that updates itself every second with a new plot."""
    def __init__(self, *args, **kwargs):
        MyMplCanvas.__init__(self, *args, **kwargs)
        timer = QtCore.QTimer(self)
        QtCore.QObject.connect(timer, QtCore.SIGNAL("timeout()"), self.update_figure)
        timer.start(1000)

    def compute_initial_figure(self):
         self.axes.plot([0, 1, 2, 3], [1, 2, 0, 4], 'r')

    def update_figure(self):
        # Build a list of 4 random integers between 0 and 10 (both inclusive)
        l = [ random.randint(0, 10) for i in xrange(4) ]

        self.axes.plot([0, 1, 2, 3], l, 'r')
        self.draw()

I modified this to essentially replace self.axes.plot with self.axes.imshow of my data. It works fine. The only problem is that when I resize the GUI, the images don't resize; whereas, the plots did.

Any suggestions?