Makes each PNG only show the difference to the previous ones pasted on top of eachother

pngdiff.py

#!/usr/bin/env python
import sys
from PIL import Image

def rgb_rgba_cmp(a, b):
	if a[0] != b[0]:
		return False
	if a[1] != b[1]:
		return False
	if a[2] != b[2]:
		return False
	return True

if len(sys.argv) <= 1:
	print("Usage: %s <inputs>" % sys.argv[0])
else:
	base = Image.open(sys.argv[1])
	basep = base.load()
	i = 0
	for cif in sys.argv[2:]:
		ci = Image.open(cif)
		if ci.mode != "RGBA":
			ci = ci.convert("RGBA")
		cip = ci.load()
		for x in range(base.size[0]):
			for y in range(base.size[1]):
				if rgb_rgba_cmp(basep[x, y], cip[x, y]):
					cip[x, y] = (0, 0, 0, 0)
		ci.save(cif)
		base.paste(ci, (0, 0), ci)
		i += 1
		sys.stdout.write("%05d/%05d\r" % (i, len(sys.argv)-2))
		sys.stdout.flush()