Tkinter pyimage doesn't exist

Question

I know there are lot of similar questions, but there aren't any simple enough that I am able to understand. I have the following code:

import Tkinter as tk
from PIL import Image, ImageTk

class MainWindow:
    def __init__(self, master):
        canvas = Canvas(master)
        canvas.pack()
        self.pimage = Image.open(filename)
        self.cimage = ImageTk.PhotoImage(self.pimage)
        self.image = canvas.create_image(0,0,image=self.cimage)


filename = full_filename
root = tk.Tk()
x = MainWindow(root)
mainloop()

and I get the following error:

TclError: image "pyimage36" doesn't exist

I've read some stuff about the image objects getting garbage cleaned but I don't quite understand it.

Answer 1

Figured it out. For some reason, while running in the debugger, if any previous executions had thrown errors I get the "pyimage doesn't exist" error. However, if I restart the debugger (or no previously executed scripts have thrown errors), then the program runs fine.