replace the magenta pixels with transparency

pillow_remove_magenta.py

# Original answer in https://stackoverflow.com/a/765774/6189341

from PIL import Image

img = Image.open("area02_level_tiles.png")    # CM:: replace area02_level_tiles.png with the name/path of the image to process
img = img.convert("RGBA")
datas = img.getdata()

newData = []
for item in datas:
    if item[0] == 255 and item[2] == 255:
        newData.append((255, 255, 255, 0))
    else:
        newData.append(item)

img.putdata(newData)
img.save("transparency.png", "PNG")