OpenCV3で画像キャプチャして顔検出してモザイク処理してから表示

http://qiita.com/yohhoy/items/313da1bbddb782fd3d7f で自分の顔がいきなり映ったときの精神的ダメージの軽減をもとめて。

facemoz.cpp

# include <vector>
# include <string>
# include <iostream>
# include <opencv2/opencv.hpp>


cv::CascadeClassifier classifier;
const char * const file = "./haarcascade.xml";
cv::Size min_face;

//! initialize
void init(int w, int h)
{
    std::cout << "frame=" << w << 'x' << h << std::endl;

    if (!classifier.load(file)) {
        std::cout << "fail to load: " << file << std::endl;
        std::exit(1);
    }
    const double scale = 0.10;
    min_face = cv::Size(w * scale, h * scale);
    std::cout << "min_face=" << min_face << std::endl;
}

//! process image frame
cv::Mat process(cv::Mat& frame)
{
    std::vector<cv::Rect> faces;
    classifier.detectMultiScale(frame, faces, 1.1, 3, 0, min_face);
    for (const auto& r : faces) {
        // mosaic filter
        const double f = 0.05;
        cv::Mat tmp;
        cv::resize(frame(r), tmp, {}, f, f);
        cv::resize(tmp, frame(r), r.size(), 0, 0, cv::INTER_NEAREST);
        // draw area border
        cv::rectangle(frame, r.tl(), r.br(), {0,0,0});
    }
    return frame;
}

int main()
{
    const char * const window = "Capture (Press ESC to exit)";
    const double scale = 0.75;
    const int delay = 32;   // [msec]

    cv::VideoCapture cap(0);
    if (!cap.isOpened()) {
        std::cerr << "fail to open cv::VideoCapture" << std::endl;
        return 2; 
    }

    const double width = cap.get(cv::CAP_PROP_FRAME_WIDTH) * scale;
    const double height = cap.get(cv::CAP_PROP_FRAME_HEIGHT) * scale;
    cap.set(cv::CAP_PROP_FRAME_WIDTH, width);
    cap.set(cv::CAP_PROP_FRAME_HEIGHT, height);
    init(width, height);

    cv::namedWindow(window);
    cv::Mat frame;
    do {
        cap >> frame;
        cv::imshow(window, process(frame));
    } while (cv::waitKey(delay) != '\x1b');

    return 0;
}

$ brew install science/opencv3
...
$ clang++ -std=c++14 -W -Wall -O2 -o facemoz facemoz.cpp -I/usr/local/opt/opencv3/include -L/usr/local/opt/opencv3/lib -lopencv_core -lopencv_highgui -lopencv_videoio -lopencv_objdetect -lopencv_imgproc
$ cp /usr/local/opt/opencv3/share/OpenCV/haarcascades/haarcascade_frontalface_default.xml haarsascade.xml
$ ./facemoz