change-color.py

# -*- coding: utf-8 -*-
#
# Change a specified color to an another one for all *.png files in current dir
#

import glob
import numpy as np
from PIL import Image

# Original values
r1, g1, b1 = 0, 65, 220
# Value that we want to replace it with
r2, g2, b2 = 0, 0, 0

for filename in glob.glob("./*.png"):
    im = Image.open(filename)
    data = np.array(im)

    red, green, blue = data[:,:,0], data[:,:,1], data[:,:,2]
    mask = (red == r1) & (green == g1) & (blue == b1)
    data[:,:,:3][mask] = [r2, g2, b2]

    im = Image.fromarray(data)
    im.save(filename)