screenshot.py

#!/usr/bin/env python

import os
from selenium import webdriver
from pyvirtualdisplay import Display

URL = "https://www.github.com/"
FILENAME = os.path.join(os.path.dirname(os.path.abspath(__file__)), "screen.png")

display = Display(visible=0, size=(1024, 768))
display.start()

driver = webdriver.Firefox()
driver.set_window_size(1024, 768)
driver.get(URL)

driver.save_screenshot(FILENAME)

driver.quit()