import Image # http://www.pythonware.com/products/pil/
import os

def pngthumbgen(pathtoimage, pathtothumb):
    """
    Generate PNG thumbnail
    """

    os.umask(022) # created files are readable by all

    im = Image.open(pathtoimage) # Open original image
    im.thumbnail((128,128)) # Generate thumb
    im.save(pathtothumb, "PNG")
    im = None

if __name__ == "__main__":
    import sys
    pngthumbgen(sys.argv[1], sys.argv[2])