openCV保存图像

//保存为png透明通道
  vector<int>opts;
  opts.push_back(IMWRITE_PAM_FORMAT_RGB_ALPHA);
  imwrite("D:/img_bgra.png", img, opts);
  //保存为单通道灰度图像
  img = cv::imread(imagePath.toStdString(), IMREAD_GRAYSCALE);
  vector<int> opts_gray;
  opts_gray.push_back(IMWRITE_PAM_FORMAT_GRAYSCALE);
  imwrite("D:/img_gray.png", img, opts_gray);
  //保存为默认的彩色BGR图像
  imwrite("D:/img_BGR.png", img);
  //保存为png彩色压缩图像
  img = imread(imagePath.toStdString(), IMREAD_ANYCOLOR);
  vector<int> opts_png_anycolor;
  opts_png_anycolor.push_back(IMWRITE_PAM_FORMAT_GRAYSCALE);
  opts_png_anycolor.push_back(9);
  imwrite("D:/img_png_anycolor.png", img, opts_png_anycolor);
  //保存为JPG高压缩比图像
  img = imread(imagePath.toStdString(), IMREAD_COLOR);
  vector<int> opts_jpeg;
  opts_jpeg.push_back(IMWRITE_JPEG_QUALITY);
  opts_jpeg.push_back(50);
  opts_jpeg.push_back(IMWRITE_JPEG_OPTIMIZE);//启用 JPEG 优化
  opts_jpeg.push_back(1);
  imwrite("D:/img_jpeg.jpg", img, opts_jpeg);