jpeglitcher.py

#!/usr/bin/env python2
# vim: set tabstop=4 shiftwidth=4 textwidth=79 cc=72,79:
"""
    jpeglitcher: Read a JPEG one byte at a time,
    occasionally making a mistake.
    Original Author: Owain Jones [github.com/erinaceous] [contact@odj.me]
"""

from __future__ import print_function
import subprocess
import argparse
import random
import struct
import time
import cv2


def parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument('-c', '--cmd', default=False)
    parser.add_argument('-l', '--loop', action='store_true', default=False)
    parser.add_argument('-o', '--output', default='/tmp/glitch.jpg')
    parser.add_argument('-p', '--prob', type=float, default=0.001)
    parser.add_argument('-r', '--range', type=int, default=1)
    parser.add_argument('-s', '--sleep', type=float, default=0.01)
    parser.add_argument('-v', '--viewer', action='store_true', default=False)
    parser.add_argument('input')
    return parser.parse_args()


def glitchy_read(inputpath, outputpath, probability=0.001, maxrange=100):
    inputfile = open(inputpath, 'rb')
    outputfile = open(outputpath, 'w+b')
    data = inputfile.read(1)
    currange = maxrange
    junk = 0
    while data != b'':
        if random.random() < probability:
            if maxrange > 1:
                currange = int(random.random() * maxrange)
                junk = 1 - int(random.random() * 2)
            outputfile.write(struct.pack('%dB' % currange,
                             *[int(random.random() * 255) for x in range(0,
                                 currange)]))
        else:
            outputfile.write(data)
        data = inputfile.read(currange + junk)


def preview(img, sleeptime=1):
    try:
        previmg = cv2.imread(img)
        cv2.imshow('jpeglitcher', previmg)
        cv2.waitKey(int(sleeptime))
    except cv2.error:
        pass


if __name__ == '__main__':
    args = parse_args()
    if args.viewer:
        import cv2
    if args.loop:
        while True:
            glitchy_read(args.input, args.output, args.prob, args.range)
            if args.viewer:
                preview(args.output)
            if args.cmd is not False:
                subprocess.call(
                    args.cmd.format(infile=args.input, outfile=args.output),
                    shell=True
                )
            time.sleep(args.sleep)
    else:
        glitchy_read(args.input, args.output, args.prob, args.range)
        if args.viewer:
            preview(args.output)