# twotone.py

from image import ImagePPM

def luminance(c):

r, g, b = c

return 0.2 * r + 0.7 * g + 0.1 * b

def twotone(c, bright, cutoff, dark):

return bright if luminance(c) > cutoff else dark

def f(c):

return twotone(c, (255, 255, 255), 110, (0, 30, 70))

def applyfn(f, img):

img.putpixel((i, j), f(img.getpixel((i, j))))

def main():

img = ImagePPM.open("sup.ppm")

applyfn(f, img)

img.save("sup2.ppm")

main()