void ColorInvert::channels_demo(Mat& image)
{
    std::vector<Mat> mv;
    split(image, mv);
    imshow("蓝色", mv[0]);
    imshow("绿色", mv[1]);
    imshow("红色", mv[2]);

    Mat dst;
    mv[0] = 0;
    merge(mv, dst);
    imshow("红色", dst);

    int from_to[] = { 0,2,1,1,2,0 };
    mixChannels(&image, 1, &dst, 1, from_to, 3);
    imshow("通道混合", dst);
}