image_grid.py

from PIL import Image
import sys
from random import shuffle
import os

imgs = [x.strip() for x in open(sys.argv[1])]
r, c = int(sys.argv[2]), int(sys.argv[3])

w, h = Image.open(imgs[0]).size

ww = w // r
hh = h // r

os.makedirs("out")
shuffle(imgs)
for k in range(20):
    imgs_ = imgs[k*r*c:(k+1)*(r*c)]

    canvas = Image.new('RGB',(w, h))

    for i in range(r):
        for j in range(c):
            im = Image.open(imgs_[i*c + j])
            im.thumbnail((ww, hh))
            canvas.paste(im, (i*ww, j*hh))

    canvas.save("out/out_%d.png" % k)
    print(k)