a tiny file differ (creates a PPM image)

# a tiny file differ (creates a PPM image)

WIDTH = 32
WHITE = "\xff\xff\xff"
RED = "\xff\0\0"
import sys

filename1, filename2, imagename = sys.argv[1:4]

with open(filename1, "rb") as f:
    d1 = f.read()
with open(filename2, "rb") as f:
    d2 = f.read()

assert len(d1) == len(d2)

HEIGHT = (len(d1) / WIDTH) + 1

pixels = []
for i,j in enumerate(d1):
    pixels.append(WHITE if d1[i] == d2[i] else RED)
#remaining pixels will be black


with open(imagename, "wb") as f:
    f.write("P6 %i %i 255 " % (WIDTH, HEIGHT))
    f.write("".join(pixels))