Qt 5 and OpenCV 4 Computer Vision Projects

Using OpenGL with OpenCV

In the preceding section, when we load the source image and flip it, we use Qt to do the work. This work can also be done by using the OpenCV library:

        img = cv::imread("./images/lizard.jpg");        cv::Mat tmp;        cv::flip(img, tmp, 0);        cvtColor(tmp, img, cv::COLOR_BGR2RGB);        // ...        glTexImage2D(            GL_TEXTURE_2D, 0, GL_RGB,            img.cols, img.rows, 0, GL_RGB, GL_UNSIGNED_BYTE, img.data);        // ...

Similarly, when saving the resulting image, we can do it like this:

        cv::Mat output(img.rows, img.cols, CV_8UC3);        glReadPixels(            0, 0, img.cols, img.rows, GL_RGB, GL_UNSIGNED_BYTE, output.data);        cv::Mat tmp;        cv::flip(output, tmp, 0);        cvtColor(tmp, output, cv::COLOR_RGB2BGR);        cv::imwrite(path.toStdString(), output);

Both QImage and cv::Mat