Python script to make a set of images look like they were scanned

generate-scans.py

#!/usr/bin/env python3

# Pre-requisite: brew install imagemagick
# Usage: ./generate-scans.py NUM_SCANS_PER_FILE

import multiprocessing
import random
import subprocess
import os
import sys

scans_per_doc = int(sys.argv[1])

def make_scan(input_filename, output_filename):
    print(input_filename, output_filename)
    gamma = random.choice(range(11)) / 10.0 + 0.5
    stretch_x = random.choice(range(11))
    stretch_y = random.choice(range(11))
    rotate = random.choice(range(21)) / 5.0 - 2.0
    input_params = f'-density 300 {input_filename}[0]'
    variable_params = f'-gamma {gamma} -linear-stretch {stretch_x}%x{stretch_y}% -rotate {rotate}'
    output_params = f'-colorspace gray -quality 95 {output_filename}'
    command = f'convert {input_params} {variable_params} {output_params}'
    subprocess.run(command, shell=True)

def make_scans(input_filename):
    for index in range(scans_per_doc):
        output_filename = input_filename.replace('.pdf', f'-{index:04}.pdf')
        make_scan(input_filename, output_filename)

filename_list = [d for d in os.listdir('.') if d.endswith('.pdf')]

if __name__ == '__main__':
    pool = multiprocessing.Pool()
    pool.map(make_scans, filename_list)