from Xlib import display, X
from PIL import Image

W,H = 200,200
dsp = display.Display(':0')
try:
    root = dsp.screen().root
    raw = root.get_image(0, 0, W,H, X.ZPixmap, 0xffffffff)
    image = Image.frombytes("RGB", (W, H), raw.data, "raw", "BGRX")
    image.save('image.png')
finally:
    dsp.close()