Define and test a function named posterize. This function expects an image and a tuple of RGB values as arguments. The function modifies the image like the blackAndWhite function, but it uses the given RGB values instead of black.

here is the blackandwhite function

here is the images.py file:

import Tkinter

import os, os.path

tk = Tkinter

_root = None

class ImageView(tk.Canvas):

def __init__(self, image,

title = "New Image",

autoflush=False):

master = tk.Toplevel(_root)

master.protocol("WM_DELETE_WINDOW", self.close)

tk.Canvas.__init__(self, master,

width = image.getWidth(),

height = image.getHeight())

self.master.title(title)

self.pack()

master.resizable(0,0)

self.image = image

self.height = image.getHeight()

self.width = image.getWidth()

self.autoflush = autoflush

self.closed = False

def close(self):

"""Close the window"""

self.closed = True

self.master.destroy()

self.image.canvas = None

_root.quit()

def isClosed(self):

return self.closed

def getHeight(self):

"""Return the height of the window"""

return self.height

def getWidth(self):

"""Return the width of the window"""

return self.width

class Image:

def __init__(self, *args):

self.canvas = None

if len(args) == 1:

name = args[0]

if type(name) != str:

raise Exception('Must be a file name')

if name[-4:].upper() != '.GIF':

raise Exception('File must be a GIF')

if not os.path.exists(args[0]):

raise Exception('File not in current directory')

self.image = tk.PhotoImage(file = args[0], master = _root)

self.filename = args[0]

self.width = self.image.width()

self.height = self.image.height()

else: # arguments are width and height

self.width, self.height = args

self.image = tk.PhotoImage(master =_root,

width = self.width,

height = self.height)

self.filename = ""

def getWidth(self):

"""Returns the width of the image in pixels"""

return self.width

def getHeight(self):

"""Returns the height of the image in pixels"""

return self.height

def getPixel(self, x, y):

"""Returns a tuple (r,g,b) with the RGB color values for pixel (x,y)

r,g,b are in range(256)

"""

value = self.image.get(x, y)

if type(value) == int:

return (value, value, value)

elif type(value) == tuple:

return value

else:

return tuple(map(int, value.split()))

def setPixel(self, x, y, color):

"""Sets pixel (x,y) to the color given by RGB values r, g, and b.

r,g,b should be in range(256)

"""

(r, g, b) = color

r = round(r)

g = round(g)

b = round(b)

color = (r, g, b)

self.image.put("{#%02x%02x%02x}" % color, (x, y))

def draw(self):

"""Creates and opens a window on an image.

The user must close the window to return control to

the caller."""

if not self.canvas:

self.canvas = ImageView(self,

self.filename)

self.canvas.create_image(self.width // 2,

self.height // 2,

image = self.image)

_root.mainloop()

def save(self, filename = ""):

"""Saves the image to filename. If no file name

is provided, uses the image's file name if there

is one; otherwise, simply returns.

If the .gif extension is not present, it is added.

"""

if filename == "":

return

else:

self.filename = filename

path, name = os.path.split(filename)

ext = name.split(".")[-1]

if ext != "gif":

filename += ".gif"

self.filename = filename

self.image.write(self.filename, format = "gif")

def clone(self):

new = Image(self.width, self.height)

new.image = self.image.copy()

return new

def __str__(self):

rep = ""

if self.filename:

rep += ("File name: " + self.filename + " ")

rep += ("Width: " + str(self.width) +

" Height: " + str(self.height))

return rep

_root = tk.Tk()

_root.withdraw()

6 from images import Image 8 def detectEdges (image, amount): ""Builds and returns a new image in which the edges of the argument image are highlighted and the colors are reduced to black and white.""n 13 def average(triple): (r, g, b) triple return (r + g + b) /3 16 blackPixel - (0, 0, 0) whitePixel-(255, 255, 255) newimage.clone() for y in range(image.getHeight() - 1): 20 21 for x in range(1, image.getWidth)): 23 24 25 26 27 28 29 30 31 32 oldPixel -image.getPixel(x, y) leftPixel-image.getPixel(x - 1, y) bottomPixel-image.getPixel(x, y + 1) oldLumaverage(oldPixel) leftLum average(leftPixel) bottomLumaverage(bottomPixel) if abs (oldLumleftLum) > amount or abs (oldLum -bottomLum) amount new.setPixel(x, y, blackPixel) else: new.setPixel(x, y, whitePixel) return new 34 35 def main(filename"smokey.gif"): 36 37 38 39 imageImage(filename) print ("Close the image window to continue.") image.draw() image2detectEdges (image, 10) print("Close the image window to continue. ") image2.draw() image3detectEdges (image, 20) print("Close the image window to continue. ") image3.draw() print("Close the image window to quit. ") 41 42 43 46 47 if__name_"__main__" 48 main() 6 from images import Image 8 def detectEdges (image, amount): ""Builds and returns a new image in which the edges of the argument image are highlighted and the colors are reduced to black and white.""n 13 def average(triple): (r, g, b) triple return (r + g + b) /3 16 blackPixel - (0, 0, 0) whitePixel-(255, 255, 255) newimage.clone() for y in range(image.getHeight() - 1): 20 21 for x in range(1, image.getWidth)): 23 24 25 26 27 28 29 30 31 32 oldPixel -image.getPixel(x, y) leftPixel-image.getPixel(x - 1, y) bottomPixel-image.getPixel(x, y + 1) oldLumaverage(oldPixel) leftLum average(leftPixel) bottomLumaverage(bottomPixel) if abs (oldLumleftLum) > amount or abs (oldLum -bottomLum) amount new.setPixel(x, y, blackPixel) else: new.setPixel(x, y, whitePixel) return new 34 35 def main(filename"smokey.gif"): 36 37 38 39 imageImage(filename) print ("Close the image window to continue.") image.draw() image2detectEdges (image, 10) print("Close the image window to continue. ") image2.draw() image3detectEdges (image, 20) print("Close the image window to continue. ") image3.draw() print("Close the image window to quit. ") 41 42 43 46 47 if__name_"__main__" 48 main()