Python: Recursive Image Resize

import imghdr, os
from PIL import Image

directory = 'C:/Users/UserBob/Desktop/RANDOM/pages'

# recursively resize images with python
for root, dirs, files in os.walk(directory):
    for image in files:
        fp = os.path.join(root,image)
        try:
            # if file is image
            if imghdr.what(fp) is not None:
                with open('fn','a+') as f:
                    f.write(fp+'\n')
                im = Image.open(fp)
                if (im.size[0] < 500) or (im.size[1] < 500):
                    #find the coeffecient to scale smallest edge to 550
                    width = 550 / float(im.size[0])
                    height = 550 / float(im.size[1])
                    ratio = max(width, height)
                    width = int(float(im.size[0]) * ratio)
                    height = int(float(im.size[1]) * ratio)
                    #NEAREST for upsizing, antialias for downsizing
                    resized_image = im.resize((width, height), Image.NEAREST)
                    resized_image.save(fp, format='JPEG')
        except Exception, e:
            print(e)