def toAlphaBlackWhite(blackImg, whiteImg):
    size = blackImg.size
    blackImg = blackImg.convert('RGBA')
    whiteImg = whiteImg.convert('RGBA')
    loadedBlack = blackImg.load()
    loadedWhite = whiteImg.load()
    for x in range(size[0]):
        for y in range(size[1]):
            blackPixel = loadedBlack[x, y]
            whitePixel = loadedWhite[x, y]
            loadedBlack[x, y] = (
                int((blackPixel[0] + whitePixel[0]) / 2),
                int((blackPixel[1] + whitePixel[1]) / 2),
                int((blackPixel[2] + whitePixel[2]) / 2),
                int(255 - 255 * getBrightness(whitePixel) - getBrightness(blackPixel))
            )
    return blackImg