qr.py

#!/usr/bin/env python2
# -*- coding: utf-8 -*-

from PIL import Image

def chunks(l, n):
    """Yield successive n-sized chunks from l."""
    for i in range(0, len(l), n):
        yield l[i:i + n]

def run_length_encode(array):
    """[0, 0, 1, 1, 1, 0, 0] => [2, 3, 2]"""
    ret = [1]
    for (pre, cur) in zip(array, array[1:]):
        if pre == cur:
            ret[-1] += 1
        else:
            ret.append(1)
    return ret

def marker_num(encodings):
    """calculate how many black/white pairs are there
       Allow 20 percent mistake"""
    max_num = 0
    num = 0
    for (pre, cur) in zip(encodings, encodings[1:]):
        if abs(cur - pre) / (1.0 * pre) - 0.2 <= 0:
            num += 1
        else:
            max_num = max(max_num, num)
            num = 0
    return max_num

class QRCode(object):
    """docstring for QRCode"""
    def __init__(self, filename):
        super(QRCode, self).__init__()
        self.img = Image.open(filename).convert('L')
        data = [0 if pixel < 127 else 255 for pixel in self.img.getdata()]
        self.data = list(chunks(data, self.img.size[0]))

    def is_qrcode(self):
        marker_nums_row = [marker_num(run_length_encode(row)) for row in self.data]
        # QRCode requires at least 14 chunks
        return any([num >= 14 for num in marker_nums_row])

import sys
import shutil
if __name__ == '__main__':
    for filename in sys.argv[1:]:
        is_qrcode = QRCode(filename).is_qrcode()
        if is_qrcode:
            shutil.move(filename, './qrcodes')
        
            print '{} : {}'.format(filename, "QRCode")