# -*- coding: utf-8 -*-

# python 3, requires python -m pip install pillow

import sys
import os
import math
from PIL import Image

if len(sys.argv) < 2:
    print('usage: %s <directory1> [directory2 [...]]'%(sys.argv[0]))
    exit(0)

def check_process(file):
    if file.split('.')[-1].lower() != 'png':
        return
    print('input: %s'%(file))
    im = Image.open(file)
    rgba_im = im.convert('RGBA')
    #rgba_im.getpixel((0, 0))
    #print(repr(rgba_im.size))
    for y in range(rgba_im.size[1]):
        for x in range(rgba_im.size[0]):
            px = rgba_im.getpixel((x, y))

            # check if px meets the color range.
            px1_expected = px[0]*1.5
            px2_expected = px[0]*2.0

            if (abs(px[1]-px1_expected) > 32) or (abs(px[2]-px2_expected) > 32):
                continue

            # get the luminance
            lum = px[0] * 0.3 + px[1] * 0.4 + px[2] * 0.3
            px = (0, int(lum), 0, px[3])

            rgba_im.putpixel((x, y), px)
    #rgba_im.save(file+'.2.png')
    rgba_im.save(file)

for rootDir in sys.argv[1:]:
    for dirName, dDirList, dFileList in os.walk(rootDir):
        for file in dFileList:
            file = os.path.normpath(dirName+'/'+file)
            check_process(file)