Recompresses a jpeg many times over to destroy quality

jpg_recompresser.py

#! /usr/bin/env python
from __future__ import print_function
import random
import sys
import os

# This code reads like a basketball (it doesn't). In my defense, I wrote this a
# long time ago, and I wrote it in one hazy evening out of rage just to spite
# people who re-compress jpegs so aggressively. I publish this only because
# there's some stuff I need to not forget (e.g. how to add grain to an image
# via imagemagick)


def run_command(cmd):
	os.system(cmd)

def add_noise(input_img, out_img):
	return "convert {} {}".format(input_img, out_img)
	rand_num = int(random.random()*100)
	rand_dir = "./TEMPFRAME.{rand_num}".format(rand_num=rand_num)
	return """
mkdir {rand_dir}
convert -quiet {input_img} +repage {rand_dir}/init.mpc
convert {input_img} -fill 'gray(50%)' -colorize 100% {rand_dir}/only_grey.mpc
convert {rand_dir}/init.mpc \
	\( {rand_dir}/only_grey.mpc -attenuate 1 -seed 100 +noise gaussian -set colorspace RGB -channel G -separate +channel -blur 0x0.5 \) \
	\( -clone 0 -clone 1 -compose overlay -composite \) \
	\( {rand_dir}/only_grey.mpc -attenuate 0.5 -seed 200 +noise gaussian -set colorspace RGB -channel G -separate +channel -blur 0x0.5 \) \
	\( -clone 2 -clone 3 -compose overlay -composite \) \
	-delete 0-3 {out_img}
rm -rf {rand_dir}""".format(input_img=input_img, out_img=out_img, rand_dir=rand_dir)

def quality_rand(initquality, x):
	return min(100, int(random.random()*10) + initquality-5)
def quality_magic(initquality, x):
	magic = [4, -5, 2, 4, -2, -3, 2, -5, 1, -1, 1, -4, -4, 4, -3, 2, -3, 2, -5, -3, 2, -4, 3, -5, 3, 3, 1, -1, 0, -4, -1, -1, -1, 2, -4, 2, -5, -2, -2, 4, -1, -5, -5, 2, -2, 1, -5, 4, 4, 3, -4, -4, 2, -4, 3, 3, 1, 1, 2, -4, -1, 1, -4, -4, 1, -3, 0, 3, 2, 4, -5, 3, 0, -4, -4, -1, -5, -4, 2, -5, -5, -1, 0, -3, 3, 3, 4, 2, 1, -5, 4, 1, 0, 1, -1, 1, -1, 2, -5, 3, -5, -2, -3, 4, 1, 1, -1, -2, 4, 0, -5, 2, 3, -4, 3, -5, 4, -2, 1, 4, -4, 3, -1, -2, 3, 1, 1, 3, -1, 0, -2, 1, 0, 4, -2, -1, -1, 0, 0, -1, 1, 0, -3, -2, 0, 2, -1, -5, -2, -4, -5, 0, 2, -5, 0, 1, 0, -2, -5, -2, 3, 0, 3, -4, -5, 2, 0, -2, 0, -1, -1, 0, 1, 2, -5, -2, -3, 3, 3, 1, -3, -2, -3, -2, 3, -2, 3, 3, -1, 4, -3, -3, 0, -3, 2, -1, -2, 2, -4]
	return initquality + magic[(x-1)%len(magic)]

def expand(prev, cur_raw):
	large_cmd = "mogrify -sample 125% {prev}"
	run_command(large_cmd.format(prev=prev))
	return 'expanded'
def shrink(prev, cur_raw):
	large_cmd = "mogrify -sample 80% {prev}"
	run_command(large_cmd.format(prev=prev))
	return 'normal'

def img_converter(startimg, count, initquality=95, q_source="rand"):
	cmds = []
	state = 'normal'
	prevjpg = "wrecked_working_image.jpg"
	cur_raw = "wrecked_working_raw_image.ppm"
	run_command(add_noise(startimg, prevjpg))

	quality_sources = {
		"rand": quality_rand,
		"magic": quality_magic
	}
	quality_func = quality_sources[q_source]

	quality = initquality
	for x in xrange(0, count+1):
		quality = quality_func(initquality, x)

		if x and not (x%50):
			if state == 'normal':
				state = expand(prevjpg, cur_raw)
			elif state == 'expanded':
				state = shrink(prevjpg, cur_raw)
		if not (x%10):
			print("\r{:>2.2f}% completed".format(float(x)/count*100), end="", file=sys.stderr)
		
		run_command("convert {prevjpg} {cur_raw} && convert {cur_raw} -quality {quality}% {prevjpg}".format(
			prevjpg=prevjpg,
			cur_raw=cur_raw,
			quality=quality
		))
		run_command("rm -f {cur_raw}".format(cur_raw=cur_raw))

	if state == 'expanded':
				state = shrink(prevjpg, cur_raw)

	run_command("cp {} wrecked_final.jpg".format(prevjpg))
	run_command("rm -f {}".format(prevjpg))

	return " && ".join(cmds)


def main():
	name = "tmp.png"
	count = 10
	quality = 85
	q_source = "rand"

	if len(sys.argv) > 1:
		name = sys.argv[1]
		if len(sys.argv) > 2:
			count = int(sys.argv[2])
			if len(sys.argv) > 3:
				quality = int(sys.argv[3])
				if len(sys.argv) > 4:
					q_source = sys.argv[4]

	cmds = img_converter(name, count, quality, q_source)

	print(file=sys.stderr)

if __name__ == '__main__':
	main()