Opencv blob检测

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官方提供sample：

#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/features2d.hpp>
#include <vector>
#include <map>
#include <iostream>

using namespace std;
using namespace cv;


static void help(char** argv)
{
    cout << "\n This program demonstrates how to use BLOB to detect and filter region \n"
        << "Usage: \n"
        << argv[0]
        << " <image1(detect_blob.png as default)>\n"
        << "Press a key when image window is active to change descriptor";
}


static String Legende(SimpleBlobDetector::Params& pAct)
{
    String s = "";
    if (pAct.filterByArea)
    {
        String inf = static_cast<const ostringstream&>(ostringstream() << pAct.minArea).str();
        String sup = static_cast<const ostringstream&>(ostringstream() << pAct.maxArea).str();
        s = " Area range [" + inf + " to  " + sup + "]";
    }
    if (pAct.filterByCircularity)
    {
        String inf = static_cast<const ostringstream&>(ostringstream() << pAct.minCircularity).str();
        String sup = static_cast<const ostringstream&>(ostringstream() << pAct.maxCircularity).str();
        if (s.length() == 0)
            s = " Circularity range [" + inf + " to  " + sup + "]";
        else
            s += " AND Circularity range [" + inf + " to  " + sup + "]";
    }
    if (pAct.filterByColor)
    {
        String inf = static_cast<const ostringstream&>(ostringstream() << (int)pAct.blobColor).str();
        if (s.length() == 0)
            s = " Blob color " + inf;
        else
            s += " AND Blob color " + inf;
    }
    if (pAct.filterByConvexity)
    {
        String inf = static_cast<const ostringstream&>(ostringstream() << pAct.minConvexity).str();
        String sup = static_cast<const ostringstream&>(ostringstream() << pAct.maxConvexity).str();
        if (s.length() == 0)
            s = " Convexity range[" + inf + " to  " + sup + "]";
        else
            s += " AND  Convexity range[" + inf + " to  " + sup + "]";
    }
    if (pAct.filterByInertia)
    {
        String inf = static_cast<const ostringstream&>(ostringstream() << pAct.minInertiaRatio).str();
        String sup = static_cast<const ostringstream&>(ostringstream() << pAct.maxInertiaRatio).str();
        if (s.length() == 0)
            s = " Inertia ratio range [" + inf + " to  " + sup + "]";
        else
            s += " AND  Inertia ratio range [" + inf + " to  " + sup + "]";
    }
    return s;
}



int main(int argc, char* argv[])
{

    Mat img = imread("F:/1.jpg", IMREAD_COLOR);
    if (img.empty())
    {

        return 1;
    }
    threshold(img, img, 150, 255, THRESH_BINARY);
    imshow("threshold", img);
    waitKey(0);
    SimpleBlobDetector::Params pDefaultBLOB;
    // This is default parameters for SimpleBlobDetector
    pDefaultBLOB.thresholdStep = 20;
    pDefaultBLOB.minThreshold = 0;
    pDefaultBLOB.maxThreshold = 220;
    pDefaultBLOB.filterByColor = false;
    pDefaultBLOB.filterByArea = false;
    pDefaultBLOB.minArea = 1;
    pDefaultBLOB.maxArea = 5000;
    pDefaultBLOB.filterByCircularity = false;
    pDefaultBLOB.filterByInertia = false;
    pDefaultBLOB.filterByConvexity = false;
    // Descriptor array for BLOB
    vector<String> typeDesc;
    // Param array for BLOB
    vector<SimpleBlobDetector::Params> pBLOB;
    vector<SimpleBlobDetector::Params>::iterator itBLOB;
    // Color palette
    vector< Vec3b >  palette;
    for (int i = 0; i < 65536; i++)
    {
        uchar c1 = (uchar)rand();
        uchar c2 = (uchar)rand();
        uchar c3 = (uchar)rand();
        palette.push_back(Vec3b(c1, c2, c3));
    }
    help(argv);


    // These descriptors are going to be detecting and computing BLOBS with 6 different params

    // Param for second BLOB detector we want area between 500 and 2900 pixels
    typeDesc.push_back("BLOB");
    pBLOB.push_back(pDefaultBLOB);
    pBLOB.back().filterByArea = true;
    pBLOB.back().minArea = 500;
    pBLOB.back().maxArea = 9999;
   
    itBLOB = pBLOB.begin();
    vector<double> desMethCmp;
    Ptr<Feature2D> b;
    String label;
    // Descriptor loop
    vector<String>::iterator itDesc;
    for (itDesc = typeDesc.begin(); itDesc != typeDesc.end(); ++itDesc)
    {
        vector<KeyPoint> keyImg1;
        if (*itDesc == "BLOB")
        {
            b = SimpleBlobDetector::create(*itBLOB);
            label = Legende(*itBLOB);
            ++itBLOB;
        }
        try
        {
            int s = cv::getTickCount();
            // We can detect keypoint with detect method
            vector<KeyPoint>  keyImg;
            vector<Rect>  zone;
            vector<vector <Point> >  region;
            Mat     desc, result(img.rows, img.cols, CV_8UC3);
            if (b.dynamicCast<SimpleBlobDetector>().get())
            {
                Ptr<SimpleBlobDetector> sbd = b.dynamicCast<SimpleBlobDetector>();
                sbd->detect(img, keyImg, Mat());
                drawKeypoints(img, keyImg, result);
                int i = 0;
                for (vector<KeyPoint>::iterator k = keyImg.begin(); k != keyImg.end(); ++k, ++i)
                    circle(result, k->pt, (int)k->size, palette[i % 65536]);
            }
            namedWindow(*itDesc + label, WINDOW_AUTOSIZE);
            int e = cv::getTickCount();
            std::cout << "SimpleBlobDetector cost time: " << static_cast<double>(e - s) / cv::getTickFrequency() * 1000 << "ms" << std::endl;
            imshow(*itDesc + label, result);
            imshow("Original", img);
            waitKey();
        }
        catch (const Exception& e)
        {
            cout << "Feature : " << *itDesc << "\n";
            cout << e.msg << endl;
        }
    }
    return 0;
}

网上提供：

mvk-nodes/blobdetect_test.cpp at master · mangosroom/mvk-nodes (github.com)

OpenCV中drawContours用法_牧羊女说的博客-CSDN博客_drawcontours