OpenCV 第2天
OpenCV 第2天

OpenCV 第2天

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

Pics after Gaussian transformation x1 & x2

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;
}
LDR

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;

}
A mess

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.

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