Tkinter create image function error (pyimage1 does not exist)

I'm a student from the outside world with no previous programming experience. I have been learning Python as an extension of my math class. I have been trying to create a program that generates fractals using Tkinter. The code works well on its own, but the inclusion of a user-input GUI causes it to give an error: ``` Exception in Tkinter callback Traceback (most recent call last): File "C:\Python33\lib\tkinter\__init__.py", line 1475, in __call__ return self.func(*args) File "C:\Python33\FractalGUI.py", line 74, in fractals canvas.create_image((0, 0), image = img, state = "normal", anchor = tkinter.NW) File "C:\Python33\lib\tkinter\__init__.py", line 2319, in create_image return self._create('image', args, kw) File "C:\Python33\lib\tkinter\__init__.py", line 2310, in _create *(args + self._options(cnf, kw)))) _tkinter.TclError: image "pyimage1" doesn't exist ``` The code itself is below. Please note that the error doesn't appear until the `canvas.create_image` line is run. If there is any other information that I can provide, please let me know. Thanks! :) ``` import tkinter from tkinter import * #Creates widgets for user input class Imagespecs(Frame): def __init__(self,master): Frame.__init__(self,master) self.grid() self.y_axis() self.x_axis() #Y axis input def y_axis(self): self.instruction = Label(self,text = "How many pixels high do you want the image?") self.instruction.grid(row = 8, column = 0, columnspan = 2, sticky = N) self.height = Entry(self) self.height.grid(row = 10, column = 1, sticky = E) #Enters info to run fractal generation self.submit_button = Button(self,text = "Submit", command = self.fractals) self.submit_button.grid(row = 14, column = 2, sticky = E) #X axis input def x_axis(self): self.instruction2 = Label(self,text = "How many pixels wide do you want the image?") self.instruction2.grid(row = 4, column = 0, columnspan = 2, sticky = E) self.width = Entry(self) self.width.grid(row = 6, column = 1, sticky = E) #generates fractal def fractals(self): #Replace non-input content = self.width.get() content2 = self.height.get() if content == "": content = 500 if content2 == "": content2 = 500 #Create window specs WIDTH = int(content2); HEIGHT = int(content) xa = -2.0; xb = 1.0 ya = -1.5; yb = 1.5 maxIt = 256 window = Tk() canvas = Canvas(window, width = WIDTH, height = HEIGHT, bg = "#000000") img = PhotoImage(width = WIDTH, height = HEIGHT) #The Newton-Raphson iteration h = HEIGHT for ky in range(HEIGHT): print (h) h = h - 1 for kx in range(WIDTH): c = complex(xa + (xb - xa) * kx / WIDTH, ya + (yb - ya) * ky / HEIGHT) z = complex(0.0, 0.0) for i in range(maxIt): z = z * z + c if abs(z) >= 2.0: break rd = hex(i % 4 * 64)[2:].zfill(2) gr = hex(i % 8 * 32)[2:].zfill(2) bl = hex(i % 16 * 16)[2:].zfill(2) img.put("#" + rd + gr + bl, (kx, ky)) canvas.create_image((0, 0), image = img, state = "normal", anchor = tkinter.NW) #Run GUI canvas.pack() mainloop() root = Tk() root.title("Fractal GUI") root.geometry("300x200") app = Imagespecs(root) root.mainloop() ```