Takes a directory of images, create pages with 6 images per page.

pytile.py

import os
import re
import sys
from subprocess import Popen

from PIL import Image
from pdf2image import convert_from_path

def pdfs_to_images(in_dir, out_dir):
    for i, f in enumerate(os.listdir(in_dir)):
        convert_from_path(os.path.join(in_dir, f), fmt='png', output_folder=out_dir, output_file=str(i))

def images_to_tiles(in_dir, out_dir):
    stacks = []
    files = os.listdir(in_dir)
    files.sort(key=lambda s: int(s.split('_')[0]) * 1000 + int(s.split('-')[-1][:-4]))
    for i in range(0, len(files) // 6 + 1):
        stacks.append(files[i * 6:(i+1) * 6])

    max_width = 1700 // 2
    max_height = 2200 // 3
    for pn, s in enumerate(stacks):
        page = Image.new("RGB", (1700, 2200), (255, 255, 255))
        for i, f in enumerate(s):
            img = Image.open(os.path.join(out_dir, f))
            img.thumbnail((1700 // 2, 2200 // 3))
            x = (i % 2) * max_width
            y = (i % 3) * max_height
            w, h = img.size
            page.paste(img, (x, y, x + w, y + h))
        page.save(os.path.join(out_dir, f"{pn}.png"))

def tiles_to_pdf(in_dir, out_dir):
    p = Popen(f"convert $(ls -1 -v {in_dir}) {out_dir}/out.pdf")
    p.communicate()

def main(args):
    in_dir = args[2]
    out_dir = args[3]

    if args[1] == "1":
        pdfs_to_images(in_dir, out_dir)
    elif args[1] == "2":
        images_to_tiles(in_dir, out_dir)
    elif args[1] == "3":
        tiles_to_pdf(in_dir, out_dir)

if __name__=='__main__':
    main(sys.argv)

To convert to PDF: convert $(ls -1 -v *.png) out.pdf