iOS launch-image resize

# this script need pillow library
# this script tested on python 2.7.13

# install pillow libary by pip
# * pip install Pillow
# usage
# * iosLaunchImageResize.py <sourceimage-filename>
# source image must have square (more than 2048 if possible)

launchImageSize = {
    "1x" : (320, 480),
    "2x" : (640, 960),
    "4" : (640, 1136),      # Retina 4
    "5.5" : (1242, 2208),   # Retina HD 5.5
    "4.7" : (750, 1334),    # Retina HD 4.7
    "5.5L" : (2208, 1242),  # Retina HD 5.5 Landscape
    "iPad1x" : (768, 1024),
    "iPad2x" : (1536, 2048),
    "iPad1xL" : (1024, 768), # Landscape
    "iPad2xL" : (2048, 1536),# Landscape
}

import os
import sys

from PIL import Image

def saveResizeImage(image, outfilename, w, h):
    rs = w if w > h else h
    rsimage = image.resize((rs, rs), Image.BICUBIC)

    x = (rs - w)/2
    y = (rs - h)/2

    box = (x, y, x + w, y + h)
    # print(box, rs)

    region = rsimage.crop(box)
    region.save(outfilename)
    del region
    return

def imageResizeMain(filename):
    im = Image.open(filename)
    for k in launchImageSize:
        s = launchImageSize[k]
        ofn = "{0}_{1}.png".format(filename.split('.')[0], k)
        saveResizeImage(im, ofn, s[0], s[1])

if __name__ == "__main__":
    args = len(sys.argv)
    if args == 2:
        imageResizeMain(sys.argv[1])