decode an ascii qrencode to an image

make_qrcode.py

# take an ascii qrcode from qrencode and make it a png

from PIL import Image
import re
import sys

try:
    with open(sys.argv[1]) as fp:
        line = fp.readline().strip('\n')

        # get columns count dynamically from file
        # file must have same length in every line
        cols = len(line)
        # we expect the white value to be a space
        zero_char = r'[ ]'
        # we expect the black value to be a hash
        one_char = r'[#]'
        # handle the first line we read above so we don't drop it in case the file is not padded
        line = re.sub(zero_char, '0', line)
        line = re.sub(one_char, '1', line)
        bitstring = line + line
        while line:
            line = fp.readline().strip('\n')
            # replace zeros and ones
            line = re.sub(zero_char, '0', line)
            line = re.sub(one_char, '1', line)
            # ascii version has to double stack the rows since there are half as many rows as columns
            bitstring += line + line
    # print bitstring out for debugging
    print(bitstring)

    # make square image the size of line length
    # make it a white image, so we only need to write black characters where there are 1's
    outimg = Image.new("RGB", (cols, cols), "white")
    pixels_out = outimg.load()
    # determine number of rows
    rows = int(len(bitstring)/cols)
    count = -1
    # write out the png row by row
    for r in range(0, rows):
        for c in range(0, cols):
            count += 1
            if bitstring[count] == "1":
                pixels_out[(c, r)] = (0, 0, 0)

    outimg.save("qrout.png", "png")

except:
    print("Run as {} location/to/qrfile.txt\nMake sure file exists and all lines of file are of same length".format(sys.argv[0]))