Why my image cannot be displayed?

[huey.y.jiang at gmail.com]

Hi All,

Image display drives me crazy. After I get it displayed, and want to do the job with a class, display failed again. Please take a look at my trial code:

from Tkinter import *

class imageDisplay:
	def __init__(self, parent=None):
		canvas = Canvas(width=400, height=300, bg='beige')
		canvas.pack()
		self.canvas = canvas
		img = PhotoImage(file="xxx.gif")
		self.canvas.create_image(150, 0, image=img, anchor=NW)

if __name__ == '__main__':
	imageDisplay()
	mainloop()

Result:  A blank canvas was displayed. No error message. 

Can somebody help? Thanks so much!