braillify.py

#!/usr/bin/env python3
import os
import sys
from PIL import Image


BRAILLE_OFFSET = 0x2800


def braillify(image_path, threshold):
    image = Image.open(image_path).convert('L')

    output = []
    for y in range(0, int(image.height / 4) * 4, 4):
        for x in range(0, int(image.width / 2) * 2, 2):
            p1 = image.getpixel((x, y))
            p2 = image.getpixel((x, y + 1))
            p3 = image.getpixel((x, y + 2))
            p4 = image.getpixel((x + 1, y))
            p5 = image.getpixel((x + 1, y + 1))
            p6 = image.getpixel((x + 1, y + 2))
            p7 = image.getpixel((x, y + 3))
            p8 = image.getpixel((x + 1, y + 3))

            n = 0
            n |= int(p1 < threshold)
            n |= int(p2 < threshold) << 1
            n |= int(p3 < threshold) << 2
            n |= int(p4 < threshold) << 3
            n |= int(p5 < threshold) << 4
            n |= int(p6 < threshold) << 5
            n |= int(p7 < threshold) << 6
            n |= int(p8 < threshold) << 7

            output.append(chr(BRAILLE_OFFSET + n))
        output.append('\n')
    return ''.join(output)


def main():
    if len(sys.argv) < 2:
        print('usage: {} /path/to/image [threshold]'.format(sys.argv[0]))
        sys.exit(1)

    image_path = sys.argv[1]
    threshold = 125
    if len(sys.argv) == 3:
        threshold = int(sys.argv[2])
    print(braillify(image_path, threshold))


if __name__ == '__main__':
    main()