import os
from pathlib import Path
from PIL import Image
from tqdm import tqdm
# we only consider jpeg artifact, not subsampling
subsampling=0
target_quailty=[10,20,30,40]
for quality in target_quailty:
    Path(f"./X{quality}").mkdir(exist_ok=True)
for file in tqdm(os.listdir(".")):
    if file.endswith(".png"):
        image_pil=Image.open(file)
        image_pil=image_pil.convert("L")
        basename=os.path.splitext(file)[0]
        for quality in target_quailty:
            image_pil.save(f"./X{quality}/{basename}.jpg","jpeg",quality=quality,subsampling=subsampling)