image-resize-500px.py

import PIL
from PIL import Image
import os
import sys
 
path = "/path/to/file"

dirs = [file for file in os.listdir(path) if file.endswith('.png')]

#pixelsize = 500;

def resize_thumbnail():
    for item in dirs:
        if os.path.isfile(path+item):
            image = Image.open(path+item)
            file_path, extension = os.path.splitext(path+item)
        image = Image.open(path+item)
        image.thumbnail((500,500), Image.ANTIALIAS)
        if image.mode in ("RGBA", "P"):
               image = image.convert("RGB")
        image.save(file_path + "_thumb.jpg" ,'JPEG', quality=90)

resize_thumbnail()