Creating ASCII Art from Images with Python and Pillow

This guide explains how to generate ASCII art from an image using Python (3.6) and the Pillow (PIL) library, requiring only about 50 lines of code.

Prerequisites include a Windows platform, Jupyter IDE, and Pillow installed via pip.

First, the image is opened, resized, and optionally blurred:

from PIL import Image
im = Image.open("C:/Users/Administrator/Desktop/柴犬.jpg")
w, h = im.size
im.thumbnail((w//2, h//2))  # scale to 50%
im.save("C:/Users/Administrator/Desktop/狗狗.jpg", "jpeg")

from PIL import Image, ImageFilter
im = Image.open("C:/Users/Administrator/Desktop/柴犬.jpg")
im2 = im.filter(ImageFilter.BLUR)
im2.save("C:/Users/Administrator/Desktop/模糊柴犬.jpg", "jpeg")

The script then defines a list of ASCII characters ordered from dark to light and uses a grayscale conversion formula (gray = 0.2126 * r + 0.7152 * g + 0.0722 * b) to map each pixel to a character.

ascii_char = list("$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/|()1{}[]?-_+~<>i!lI;:,\"^`'. ")
WIDTH = 120
HEIGHT = 60

def get_char_from_pixel(r, g, b, alpha=256):
    if alpha == 0:
        return " "
    length = len(ascii_char)
    gray = int(0.2126 * r + 0.7152 * g + 0.0722 * b)
    unit = (256.0 + 1) / length
    return ascii_char[int(gray / unit)]

def ascii_pic_from_pil(path):
    text = ""
    im = Image.open(path)
    im = im.resize((WIDTH, HEIGHT), Image.NEAREST)
    for h in range(im.size[1]):
        for w in range(im.size[0]):
            text += get_char_from_pixel(*im.getpixel((w, h)))
        text += "\n"
    return text

def save_to_file(filename, pic_str):
    with open(filename, 'w') as f:
        f.write(pic_str)

img = ascii_pic_from_pil('C:/Users/Administrator/Desktop/狗狗.jpg')
save_to_file('C:/Users/Administrator/Desktop/狗狗.txt', img)

Running the script creates a .txt file containing the ASCII representation, which can be viewed in a terminal; the visual result may differ depending on the terminal’s font, line height, and width settings.