OpenCV图像翻转和旋转

  QString appPath = QCoreApplication::applicationDirPath();
	imagePath = appPath + "/A.jpg";
	img = cv::imread(imagePath.toStdString());
	if (img.empty())
		return;

	Mat dst;
	flip(img, dst, 0);//上下翻转
	imshow("flip0", dst);
	flip(img, dst, 1);//左右翻转
	imshow("flip1", dst);
	flip(img, dst, -1);//180°旋转
	imshow("flip-1", dst);

  int h = img.rows;
	int w = img.cols;
	Mat M = getRotationMatrix2D(Point2f(w / 2, h / 2), 45, 1.0);

	double cos = abs(M.at<double>(0, 0));
	double sin = abs(M.at<double>(0, 1));
	int nw = cos * w + sin * h;
	int nh = sin * w + cos * h;

	M.at<double>(0, 2) = M.at<double>(0, 2) + (nw / 2 - w / 2);
	M.at<double>(1, 2) = M.at<double>(1, 2) + (nh / 2 - h / 2);

	warpAffine(img, dst, M, Size(nw,nh),INTER_LINEAR,0,Scalar(255,0,0));
	imshow("rotate", dst);

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