https://emptystack.top/crt_gif/

crtgif.py

# -*- coding: utf-8 -*-

from PIL import Image
import sys

ROW = 40
FPS = 60

if len(sys.argv) < 1:
    print("Please specify picture name.")

im = Image.open(sys.argv[1])

width, height = im.size

frames = []
box = (0, 0, width, ROW)
for i in range(0, height, ROW):
    region = im.crop(box)
    blank = Image.new(im.mode, im.size)
    blank.paste(region, box)
    frames.append(blank)
    box = (0, box[3], width, box[3] + ROW if box[3] + ROW < height else height)

frames[0].save(
    im.filename[: im.filename.find(".", 1)] + "_crt.gif",
    "GIF",
    # https://www.quora.com/What-is-the-optimal-frame-rate-for-an-animated-GIFS
    duration=round(1 / FPS * 100) * 10,
    save_all=True,
    append_images=frames[1:],
    loop=0,
)