OpenCV通道分离、合并、混和

QString appPath = QCoreApplication::applicationDirPath();
  imagePath = appPath + "/A.jpg";
  img = cv::imread(imagePath.toStdString());
  if (img.empty())
    return;
  std::vector<Mat> mv;
  cv::split(img, mv);
  imshow("B", mv[0]);
  imshow("G", mv[1]);
  imshow("R", mv[2]);
  cv::Mat dst;
  mv[1] = 0;
  mv[2] = 0;
  cv::merge(mv, dst);
  imshow("Blue", dst);
  int from_to[] = { 0,2,1,1,2,0 };
  cv::mixChannels(&img, 1, &dst, 1, from_to,3);
  imshow("通道混合", dst);