img2ascii.py

# Python code to convert an image to ASCII image.
import sys, random, argparse
import numpy as np
import math

from PIL import Image

# gray scale level values from:
# http://paulbourke.net/dataformats/asciiart/

# 70 levels of gray
gscale1 = "$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/\|()1{}[]?-_+~<>i!lI;:,\"^`'. "

# 10 levels of gray
gscale2 = '@%#*+=-:. '


def getAverageL(image):
    """
    Given PIL Image, return average value of grayscale value
    """
    # get image as numpy array
    im = np.array(image)

    # get shape
    w, h = im.shape

    # get average
    return np.average(im.reshape(w * h))


def covertImageToAscii(fileName, cols, scale, moreLevels):
    """
    Given Image and dims (rows, cols) returns an m*n list of Images
    """
    # declare globals
    global gscale1, gscale2

    # open image and convert to grayscale
    image = Image.open(fileName).convert('L')

    # store dimensions
    W, H = image.size[0], image.size[1]

    # compute width of tile
    w = W / cols

    # compute tile height based on aspect ratio and scale
    h = w / scale

    # compute number of rows
    rows = int(H / h)

    # check if image size is too small
    if cols > W or rows > H:
        exit(0)

    # ascii image is a list of character strings
    aimg = []
    # generate list of dimensions
    for j in range(rows):
        y1 = int(j * h)
        y2 = int((j + 1) * h)

        # correct last tile
        if j == rows - 1:
            y2 = H

        # append an empty string
        aimg.append("")

        for i in range(cols):

            # crop image to tile
            x1 = int(i * w)
            x2 = int((i + 1) * w)

            # correct last tile
            if i == cols - 1:
                x2 = W

            # crop image to extract tile
            img = image.crop((x1, y1, x2, y2))

            # get average luminance
            avg = int(getAverageL(img))

            # look up ascii char
            if moreLevels:
                gsval = gscale1[int((avg * 69) / 255)]
            else:
                gsval = gscale2[int((avg * 9) / 255)]

            # append ascii char to string
            aimg[j] += gsval

    # return txt image
    return aimg


def IMG2ASCII(outFile, imgFile):
    scale = 0.5
    cols = 300
    moreLevels = 0
    aimg = covertImageToAscii(imgFile, cols, scale, moreLevels)
    f = open(outFile, 'a+')

    # write to file
    for row in aimg:
        f.write(row + '\n')

    f.close()

# Code taken from:
# https://www.geeksforgeeks.org/converting-image-ascii-image-python/