python image resize

import PIL
import sys
from PIL import Image

baseheight = 660
img = Image.open(sys.argv[1])
print(img.size)
if img.size[1] < baseheight:
    print('Image too small')
else:
    hpercent = (baseheight / float(img.size[1]))
    wsize = int((float(img.size[0]) * float(hpercent)))
    img = img.resize((wsize, baseheight), PIL.Image.ANTIALIAS)
    img.save("resized_" + sys.argv[1])