imessage_app_icon.py

from PIL import Image

original_11 = "1024.png"
original_43 = "1024x768.png"

im = Image.open(original_11)

variants_11 = [
    58,
    87,
]
variants = [
    (120, 90),
    (180, 135),
    (134, 100),
    (148, 110),
    (54, 40),
    (81, 60),
    (64, 48),
    (96, 72),
]

for v in variants_11:
    im = Image.open(original_11)
    n = im.resize((v, v), Image.ANTIALIAS)
    n.save("{}x{}.png".format(v, v))

for (x,y) in variants:
    im = Image.open(original_43)
    n = im.resize((x, y), Image.ANTIALIAS)
    n.save("{}x{}.png".format(x, y))