stitcher.py

import pygame
import glob
import math


tiles = [pygame.image.load(tile) for tile in glob.glob('*.png')]
tile_length = max([max([tile.get_width(), tile.get_height()]) for tile in tiles])

side = math.ceil(math.sqrt(len(tiles)))

stitched = pygame.surface([side * tile_length, side * tile_length], pygame.SRCALPHA, 32)
for index, tile in tiles:
    x = index % side
    y = int(index / side)
    stitched.blit(tile, (x * tile_length, y * tile_length))

pygame.image.save(stitched, 'stitched.png')