Python Turtle Image Plotter

from PIL import Image
import turtle

def get_image_data(image_filepath):

    image = Image.open(image_filepath)
    pixels = image.load()
    width, height = image.size
    return width, height, pixels

def pixel_tuple_to_hex(pixel_tuple):

    hex_code = "#"
    for rgb in pixel_tuple:
        if len(str(hex(rgb))) < 4:
            hex_code += "0" + str(hex(rgb))[-1:]
        else:
            hex_code += str(hex(rgb))[-2:]
    return hex_code

def pixel_tuple_to_ascii(pixel_tuple):

    total = sum(pixel_tuple)
    if total > 612:
        return " "
    if total > 459:
        return "~"
    if total > 306:
        return "+"
    if total > 153:
        return "@"
    else:
        return "#"

def turtle_plot_pixel(turtle,size):

    turtle.begin_fill()
    for i in range(4):
        turtle.forward(size)
        turtle.right(90)
    turtle.forward(size)
    turtle.end_fill()

def turtle_plot_image(image_width, image_height, image_pixels, pixel_size):

    turtlex = 0-(image_width*(pixel_size/2))
    turtley = image_height*(pixel_size/2)

    canvas = turtle.Screen()
    canvas.setup(width = image_width*pixel_size, height = image_height*pixel_size, startx = turtlex, starty = turtley)

    t = turtle.Turtle()
    t.speed(999)
    t.penup()
    t.setx(turtlex)
    t.sety(turtley)
    t.pendown()

    for y in range(image_height):
        for x in range(image_width):
            t.color(pixel_tuple_to_hex(image_pixels[x,y]))
            turtle_plot_pixel(t,pixel_size)
        t.penup()
        turtley -= pixel_size
        t.setx(turtlex)
        t.sety(turtley)
        t.pendown()

    canvas.mainloop()

def ascii_plot_image(image_width, image_height, image_pixels, ascii_filename):
    text_file = open(ascii_filename,"w")
    ascii_conversion = []

    for y in range(image_height):
        current_line = []
        for x in range(image_width):
            current_line.append(pixel_tuple_to_ascii(image_pixels[x,y]))
        ascii_conversion.append(current_line)

    for line in ascii_conversion:
        text_file.writelines("".join(line)+"\n")

    text_file.close()

def image_to_turtle(image_filepath,pixel_size):
    image_width, image_height, image_pixels = get_image_data(image_filepath)
    turtle_plot_image(image_width, image_height, image_pixels, pixel_size)

def image_to_ascii(image_filepath,ascii_filename):
    image_width, image_height, image_pixels = get_image_data(image_filepath)
    ascii_plot_image(image_width, image_height, image_pixels, ascii_filename)

image_to_ascii("pika.jpg","pika_ascii.txt")
image_to_turtle("pika.jpg",25)