opencv: Rotate image by 90, 180 or 270 degrees
opencv2:
void rotate_cw(const cv::Mat& image, cv::Mat& dest, int degrees) { switch (degrees % 360) { case 0: dest = image.clone(); break; case 90: cv::flip(image.t(), dest, 1); break; case 180: cv::flip(image, dest, -1); break; case 270: cv::flip(image.t(), dest, 0); break; default: cv::Mat r = cv::getRotationMatrix2D({image.cols/2.0F, image.rows/2.0F}, degrees, 1.0); int len = std::max(image.cols, image.rows); cv::warpAffine(image, dest, r, cv::Size(len, len)); break; //image size will change } }
opencv3:
void cv::rotate(InputArray src, OutputArray dst, int rotateCode )
Rotates a 2D array in multiples of 90 degrees. The function rotate rotates the array in one of three different ways: Rotate by 90 degrees clockwise (rotateCode = ROTATE_90). Rotate by 180 degrees clockwise (rotateCode = ROTATE_180). Rotate by 270 degrees clockwise (rotateCode = ROTATE_270).
Core.rotate(Mat src, Mat dst, Core.ROTATE_90_CLOCKWISE); //ROTATE_180 or ROTATE_90_COUNTERCLOCKWISE