MmapSurfaces — wiki
# Use mmap to create pygame surfaces in files.
import mmap
import os
import pygame
width, height = 64,64
size = width * height * 3
test_file_name = "map_test.txt"
if not os.path.exist(test_file_name):
f = open(test_file_name, "wb")
f.close()
f = open(test_file_name, "r+")
# memory-map the file, size 0 means whole file
amap = mmap.mmap(f.fileno(), size, access=mmap.ACCESS_WRITE )
s = pygame.image.frombuffer(amap, (width,height), "RGB")
print s.get_at((0,0))
print s.set_at((0,0), (33,33,33,255))