Turn all black pixels in an image into transparent ones

def make_transparent(image):
    """Turn all black pixels in an image into transparent ones"""
    data = image.copy().getdata()
    modified = []
    for item in data:
        if _check_pixel(item) is True:
            modified.append((255, 255, 255, 255))  # White transparent pixel
            continue
        modified.append(item)
    image.putdata(modified)
    return image