resize images for Android

resizeForAndroid.py

import os
import glob
from PIL import Image
from math import ceil
xhdpi2hdpi=0.75
hdpi2mdpi=2/3.
mdpi2ldpi=0.75
for asset in glob.glob('drawable-xhdpi/*png'):
	img = Image.open(asset)
	xhdpi = img.size
	hdpi = [ceil(xhdpi2hdpi*x) for x in xhdpi]
	mdpi = [ceil(hdpi2mdpi*x) for x in hdpi]	
	ldpi = [ceil(mdpi2ldpi*x) for x in mdpi]
	asset_name=os.path.basename(asset)
	for convert_factor,dir_name in [(hdpi,'hdpi'),(mdpi,'mdpi'),(ldpi,'ldpi')]:
		os.system("convert -resize %dx%d %s drawable-%s/%s" % \
			(convert_factor[0],convert_factor[1],asset,dir_name,asset_name))