convert image white to transparency

convert_image.py

from PIL import Image, ImageOps


def convert(src, dst, size=(224, 224)):

    original = Image.open(src)

    thumb = ImageOps.fit(original, size, Image.ANTIALIAS)

    if thumb.mode == 'RGBA':
        # convert transparency to white
        thumb.load() # test
        background = Image.new('RGB', thumb.size, (255, 255, 255))
        background.paste(thumb, mask=thumb.split()[3])
        thumb = background

    # convert ot png with white as transparency
    thumb = thumb.convert("RGBA")
    datas = thumb.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)

    thumb.putdata(newData)

    thumb.save(dst, 'PNG')


if __name__ == '__main__':
    convert('media/product/weetabix-crispy-minis-fruit-nut-292141.png', 'res.png')