#!/usr/local/bin/python

import sys, Image

if len(sys.argv) < 4:
    print 'Usage:', sys.argv[0], 'rgb-image alpha-image output-image'
    sys.exit(1)

img = Image.open(sys.argv[1]).convert('RGBA')
alpha = Image.open(sys.argv[2]).convert('L')
if alpha.size != img.size:
	alpha = alpha.resize(img.size)
img.putalpha(alpha)
img.save(sys.argv[3])