dupes.py: take jpeg and integers, intelligently create duplicates at indicated sizes

dupes.py

from __future__ import division
import os, sys
from PIL import Image

# Takes jpeg and a series of integers, intelligently creates duplicates at indicated sizes.
# Also replaces spaces with underscores and lowercases filenames.

# Usage:

# $ python dupes.py My\ Fabulous\ Image.jpg 1200 800 500

# created my_fabulous_image_1200.jpg
# created my_fabulous_image_800.jpg
# created my_fabulous_image_500.jpg

source = sys.argv[1]
sizes = sys.argv[2:]
i = Image.open(source)
oldPath = os.path.dirname(source)
baseName, ext = os.path.splitext(os.path.basename(source)) # ext not needed
newBaseName = baseName.replace(' ', '_').lower()
width = i.size[0]
height = i.size[1]
if (oldPath): oldPath += '/' # path needs a trailing slash if it exists

for s in sizes:
    s = int(s)
    if width > height:
        newSize = (s, int((height * (s / width))))
    else:
        newSize = (int((width * (s / height))), s)        
    newImage = i.resize(newSize, Image.ANTIALIAS)
    newPath = newBaseName + '_' + str(s) + '.jpg'
    newImage.save(oldPath + newPath, "JPEG", quality=90)
    print('created ' + oldPath + newPath)