• Open Source Computer Vision Library

支持向量机

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本程序为opencv2.4.6版本中自带例程introduction_to_svm.cpp 用于对svm的基本使用方法进行示范,运行结果如下图:


Image:svmresult.png


代码:

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/ml/ml.hpp>
 
using namespace cv;
 
int main()
{
    // Data for visual representation
    int width = 512, height = 512;
    Mat image = Mat::zeros(height, width, CV_8UC3);
 
    // Set up training data
    float labels[4] = {1.0, -1.0, -1.0, -1.0};
    Mat labelsMat(4, 1, CV_32FC1, labels);
 
    float trainingData[4][2] = { {501, 10}, {255, 10}, {501, 255}, {10, 501} };
    Mat trainingDataMat(4, 2, CV_32FC1, trainingData);
 
    // Set up SVM's parameters
    CvSVMParams params;
    params.svm_type    = CvSVM::C_SVC;
    params.kernel_type = CvSVM::LINEAR;
    params.term_crit   = cvTermCriteria(CV_TERMCRIT_ITER, 100, 1e-6);
 
    // Train the SVM
    CvSVM SVM;
    SVM.train(trainingDataMat, labelsMat, Mat(), Mat(), params);
 
    Vec3b green(0,255,0), blue (255,0,0);
    // Show the decision regions given by the SVM
    for (int i = 0; i < image.rows; ++i)
        for (int j = 0; j < image.cols; ++j)
        {
            Mat sampleMat = (Mat_<float>(1,2) << i,j);
            float response = SVM.predict(sampleMat);
 
            if (response == 1)
                image.at<Vec3b>(j, i)  = green;
            else if (response == -1)
                 image.at<Vec3b>(j, i)  = blue;
        }
 
    // Show the training data
    int thickness = -1;
    int lineType = 8;
    circle(	image, Point(501,  10), 5, Scalar(  0,   0,   0), thickness, lineType);
    circle(	image, Point(255,  10), 5, Scalar(255, 255, 255), thickness, lineType);
    circle(	image, Point(501, 255), 5, Scalar(255, 255, 255), thickness, lineType);
    circle(	image, Point( 10, 501), 5, Scalar(255, 255, 255), thickness, lineType);
 
    // Show support vectors
    thickness = 2;
    lineType  = 8;
    int c     = SVM.get_support_vector_count();
 
    for (int i = 0; i < c; ++i)
    {
        const float* v = SVM.get_support_vector(i);
        circle(	image,  Point( (int) v[0], (int) v[1]),   6,  Scalar(128, 128, 128), thickness, lineType);
    }
 
    imwrite("result.png", image);        // save the image
 
    imshow("SVM Simple Example", image); // show it to the user
    waitKey(0);
 
}
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