title: blank GUI with python image slideshow
body: <p>I'm having problems getting images to display during a slideshow. When the first four lines of update_image is commented out, the first image (1.png) is shown. But when its not commented, I get a blank GUI. Anyone have any suggestions?</p>
  
  <pre><code>    import Tkinter
      import Image, ImageTk
  
      class App():
          def __init__(self):
              self.root = Tkinter.Tk()
              image1=Image.open('C:\Users\Jason\Desktop\ScreenShots\\1.png')
              self.root.geometry('%dx%d' % (image1.size[0],image1.size[1]))
              tkpi=ImageTk.PhotoImage(image1)
              label_image=Tkinter.Label(self.root, image=tkpi)
              label_image.place(x=0,y=0,width=image1.size[0],height=image1.size[1])
  
              self.update_image()
              self.root.mainloop()
  
  
          def update_image(self):
              image1=Image.open('C:\Users\Jason\Desktop\ScreenShots\\2.png')
              tkpi=ImageTk.PhotoImage(image1)
              label_image=Tkinter.Label(self.root, image=tkpi)
              label_image.place(x=0,y=0,width=image1.size[0],height=image1.size[1])
  
              print 'slide'
              self.root.after(500, self.update_image)
  
      app=App()
  </code></pre>