HW help

from graphics import *
import sys

def inverted_color(picture):
    Width = picture.getWidth()
    Height = picture.getHeight()
    for x in range(Width):
        colours = x.getPixel()
        colourstring = color_rgb(225 - colours[RED], 225 - colours[GREEN], 225 - colours[BLUE])
        picture.setPixel(colourstring, colourstring, colourstring)
        #for y in range(Height):


def Sepia():
    pass

def Shuffle():
    pass


def main():
    image = input('Please enter a filename ')
    try:
        img = Image(Point(0,0), image)
    except tk.TclError:
        print('Not a valid file type!')
        sys.exit()
    area = img.getWidth() * img.getHeight()
    if area == 0:
        print('Not a valid image!!')
        sys.exit()
    cloned_img = img.clone()
    loop = 0
    while loop == 0:
        print('a. Invert image colors')
        print('b. Convert image to sepia.')
        print('c. Shuffle the image.')
        choice = input('What would you like to do? ')
        choice = choice.lower()
        if choice == 'a':
            inverted_color(cloned_img)
            loop = loop + 1
        if choice == 'b':
            colors = img.getPixel(0,0)
            loop = loop + 1
        if choice == 'c':
            colors = img.getPixel(0,0)
            loop = loop + 1

    newfilename = input('What do you want to call the file? ')
    try:
        img.save(newfilename)

    except tk.TclError:
        print('That is not a valid file!')

main()