YIQ python script

yiq.py

#!/usr/bin/env python
# coding: utf-8
import operator
import itertools

from operator import getitem
from itertools import starmap
import colorsys
import PIL
from PIL import Image


# hacer algo con 'y'

# defino estas funciones por que la conversión que define python en colorsys
# anda raro....
def dotproduct(vec1, vec2, sum=sum, imap=itertools.imap, mul=operator.mul):
    return sum(imap(mul, vec1, vec2))

def yiq2rgb(color):
    dp = dotproduct
    r = int(dp((1, 0.9563, 0.621), color))
    g = int(dp((1, -0.2721, -0.6474), color))
    b = int(dp((1, -1.1070, 1.7046), color))
    return (r, g, b)

from os.path import splitext, extsep
def default_output_filename(fname):
    ''' A.jpg -> A-out.jpg '''
    pathname, ext = splitext(fname)
    return pathname + "-out" + ext
 
def process_image(fin, fout = None):
    '''
    @param fin: An image path
    '''
    im = Image.open(fin)
    fout = fout or default_output_filename(fin) 
        
    data = list(im.getdata())
    yiq = starmap(colorsys.rgb_to_yiq, data)
    y = map(lambda point: getitem(point, 0), yiq)
    i = map(lambda point: getitem(point, 1), yiq)
    q = map(lambda point: getitem(point, 2), yiq)
    
    rgb = map(yiq2rgb, zip(y, i, q))


    im3 = Image.new('RGB', im.size)
    im3.putdata(rgb)
    im3.save(fout)
    return fout

import sys

def main(argv = sys.argv):
    from argparse import ArgumentParser
    from datetime import datetime
    parser = ArgumentParser("Yiq tool.")
    parser.add_argument('input', nargs = '?')
    parser.add_argument('output', nargs = '?', default = None)
    args = parser.parse_args()
    output_file = process_image(args.input, args.output)
    print "%s created at %s" % (output_file, datetime.now().strftime("%X %x"))
    
if __name__ == '__main__':
    sys.exit(main())