Gaussian Transformation

#include ...
int main(int argc, char** argv){
    cv::namedWindow("Example3-in",cv::WINDOW_AUTOSIZE);
    cv::namedWindow("Example3-out1",cv::WINDOW_AUTOSIZE);
    cv::namedWindow("Example3-out2",cv::WINDOW_AUTOSIZE);

    cv::Mat input = cv::imread(argv[1]);
    cv::imshow("Example3-in",input);

    cv::Mat output;
    cv::GaussianBlur(input, output, cv::Size(5,5),3,3);
    cv::imshow("Example3-out1",output);
    cv::GaussianBlur(output, output, cv::Size(5,5),3,3);

    cv::imshow("Example3-out2",output);
    cv::waitKey(0);
    return 0;
}

>> \source\repos\opencvtest\x64\Debug> .\opencvtest.exe 1.jpg

Blur and Downsample

int main(int argc, char** argv){
    cv::Mat img1,img2;

    cv::namedWindow("Example4",cv::WINDOW_AUTOSIZE);
    cv::namedWindow("Example5",cv::WINDOW_AUTOSIZE);

    img1 = cv::imread(argv[1]);
    cv::imshow("Example4",img1);

    cv::pyrDown(img1,img2);
    cv::imshow("Example5",img2);
    cv::waitKey(0);
    return 0;
}

Canny Edge Detection

• image 单通道输入图像
• edges 单通道存储边缘的输出图像
• threshold1 第一个阈值
• threshold2 第二个阈值
• aperture_size Sobel 算子内核大小

函数 cvCanny 采用 CANNY 算法发现输入图像的边缘而且在输出图像中标识这些边缘。threshold1和threshold2当中的小阈值用来控制边缘连接，大的阈值用来控制强边缘的初始分割。

int main(int argc, char** argv){
    cv::Mat img_rgb, img_gry, img_cny;
    cv::namedWindow("Example Gray",cv::WINDOW_AUTOSIZE);
    cv::namedWindow("Example Canny",cv::WINDOW_AUTOSIZE);

    img_rgb = cv::imread(argv[1]);

    cv::cvtColor(img_rgb, img_gry, cv::COLOR_BGR2GRAY);
    cv::imshow("Example Gray", img_gry);

    cv::Canny(img_gry,img_cny,10,500,3,true);
    cv::imshow("Example Canny", img_cny);

    cv::waitKey(0);
    return 0;
}

Canny with Double pyrDown

int main(int argc, char** argv){
    cv::Mat img_rgb, img_gry, img_pyr, img_cny;
    cv::namedWindow("Example7",cv::WINDOW_AUTOSIZE);
    cv::namedWindow("Example Canny with double pyrDown",cv::WINDOW_AUTOSIZE);

    img_rgb = cv::imread(argv[1]);

    cv::imshow("Example7",img_rgb);
    cv::cvtColor(img_rgb, img_gry, cv::COLOR_BGR2GRAY);
    cv::pyrDown(img_gry,img_pyr);
    cv::pyrDown(img_pyr,img_pyr);
    cv::Canny(img_pyr,img_cny,10,100,3,true);
    cv::imshow("Example Canny with double pyrDown", img_cny);

    cv::waitKey(0);
    return 0;
}

Catch Ya!

int main(int argc, char** argv){
    namedWindow("Example8: Catch Ya!",cv::WINDOW_AUTOSIZE);
    VideoCapture VideoStream(CAP_DSHOW);

    if (!VideoStream.isOpened()) {
        cout << "Error: Cannot open video stream from camera" << endl;
        return 1;
    }
    Mat image;
    while(true){
        VideoStream.read(image);
        if (image.rows <= 0 || image.cols <= 0) {
            cout << "Camera did not grap  the image" << endl;
        }
        imshow("Example8: Catch Ya!",image);
        char c = (char)cv::waitKey(16.67);
        if (c == 27)
            break;
    }
    return 0;

}

VideoStream可以换成VideoCapture类，效果一样。

当然，还有些阴间玩意：

int main(int argc, char** argv){
    cv::namedWindow("Example8: Catch Ya!",cv::WINDOW_AUTOSIZE);
    cv::VideoCapture cap;
    if(argc==1)
        cap.open(CAP_DSHOW);
    else
        cap.open(argv[1]);

    if(!cap.isOpened())
        std::cerr << "No camera!" << std::endl;

    Mat image,img_pyr,img_gry,img_cny;
    while(true){
        cap.read(image);
        cv::cvtColor(image,img_gry,cv::COLOR_BGR2GRAY);
        cv::pyrDown(img_gry, img_pyr);
        cv::Canny(img_gry,img_cny,10,100,3,true);
        imshow("Example8: Catch Ya!",img_cny);
        char c = (char)cv::waitKey(16.67);
        if (c == 27)
            break;
    }
    return -1;
}

不想放截图了，其实就是DownSampling & Canny Edge Detection视频.