#!/usr/bin/python
from PIL import Image
width = 300
img = Image.open('image.jpg')
ratio = (basewidth / float(img.size[0]))
height = int((float(img.size[1]) * float(ratio)))
img = img.resize((basewidth, height), PIL.Image.ANTIALIAS)
img.save('resized_image.jpg')

python text.py 
Traceback (most recent call last):
  File "text.py", line 7, in <module>
    ratio = (basewidth / float(img.size[0]))
NameError: name 'basewidth' is not defined

python text.py 
Traceback (most recent call last):
  File "text.py", line 9, in <module>
    img = img.resize((basewidth, height), PIL.Image.ANTIALIAS)
NameError: name 'PIL' is not defined

import PIL

#!/usr/bin/python
import PIL
from PIL import Image
basewidth = 300
img = Image.open('avatar.png')
ratio = (basewidth / float(img.size[0]))
height = int((float(img.size[1]) * float(ratio)))
img = img.resize((basewidth, height), PIL.Image.ANTIALIAS)
img.save('resized_image.png')