Python - Hacer una funcion scale para cambiar el tamaño de una imagen

# resize an image using the PIL image library

# free from:  http://www.pythonware.com/products/pil/index.htm

import Image

# open an image file (.bmp,.jpg,.png,.gif) you have in the working folder

imageFile = "zFlowers.jpg"

im1 = Image.open(imageFile)

# adjust width and height to your needs

width = 500

height = 420

# use one of these filter options to resize the image

im2 = im1.resize((width, height), Image.NEAREST)      # use nearest neighbour

im3 = im1.resize((width, height), Image.BILINEAR)     # linear interpolation in a 2x2 environment

im4 = im1.resize((width, height), Image.BICUBIC)      # cubic spline interpolation in a 4x4 environment

im5 = im1.resize((width, height), Image.ANTIALIAS)    # best down-sizing filter

ext = ".jpg"

im2.save("NEAREST" + ext)

im3.save("BILINEAR" + ext)

im4.save("BICUBIC" + ext)

im5.save("ANTIALIAS" + ext)

from PIL import Image

image_file = "french_flag.bmp"

#abrimos la imagen

img = Image.open(image_file)

# cogemos la anchura y altura

width, height = img.size