img = Image.open('img.png')
img = img.convert('RGBA')
datas = img.getdata()
newData = []
for item in datas:
    if item[0] == 255 and item[1] == 255 and item[2] == 255:
        newData.append((255, 255, 255, 0))
else:
    newData.append(item)
img.putdata(newData)
img.save('img2.png', 'PNG')
Using PIL to make all white pixels transparent?