[opencv]三通道图像反色

1.用纯白图像-原图

    Mat img = imread(path);
    imshow("src", img);
    waitKey();

    Mat white = cv::Mat(250,250,CV_8UC3,Scalar(255,255,255));
    imshow("white", white);
    waitKey();

    Mat dst = white - img;
    imshow("dst", dst);
    waitKey();