Get width and height from an image file

image_width_height.py

#! /usr/bin/python
from PIL import Image
import sys

if len(sys.argv) >= 2:
    image_file = sys.argv[1]

    try:
        img = Image.open(image_file)
        width, height = img.size
        sys.stdout.write('width: {0}px; height: {1}px;'.format(width, height))
        sys.stdout.write('\n')
    except IOError:
        sys.stderr.write('The file is not an image')
        sys.stderr.write('\n')
else:
    sys.stderr.write('Add a parameter')
    sys.stderr.write('\n')