blob(斑点)特征，SimpleBlobDetector（OpenCV案例源码detect_blob.cpp解读）

Blob是指图像中的一块连通区域，Blob分析就是对前景/背景分离后的二值图像，进行连通域提取和标记。

知识点就是SimpleBlobDetector的使用，blob(斑点)筛选条件：斑点颜色、面积、圆度、惯性率、凸度，参数解读链接

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

using namespace std;
using namespace cv;
int main()
{
    Mat src=imread("D:/sunflower.png");
    //*参数设置，以下都是默认参数
    SimpleBlobDetector::Params pDefaultBLOB;
    pDefaultBLOB.thresholdStep = 10;
    pDefaultBLOB.minThreshold = 50;
    pDefaultBLOB.maxThreshold = 220;
    pDefaultBLOB.minRepeatability = 2;
    pDefaultBLOB.minDistBetweenBlobs = 10;
    pDefaultBLOB.filterByColor = true;
    pDefaultBLOB.blobColor = 0;
    pDefaultBLOB.filterByArea = true;
    pDefaultBLOB.minArea = 25;
    pDefaultBLOB.maxArea = 5000;
    pDefaultBLOB.filterByCircularity = false;
    pDefaultBLOB.minCircularity = 0.8f;
    pDefaultBLOB.maxCircularity = (float)3.40282e+038;
    pDefaultBLOB.filterByInertia = true;
    pDefaultBLOB.minInertiaRatio = 0.1f;
    pDefaultBLOB.maxInertiaRatio = (float)3.40282e+038;
    pDefaultBLOB.filterByConvexity = true;
    pDefaultBLOB.minConvexity = 0.95f;
    pDefaultBLOB.maxConvexity = (float)3.40282e+038;
    //*用参数创建对象
    Ptr<SimpleBlobDetector> blob=SimpleBlobDetector::create(pDefaultBLOB);
    //Ptr<SimpleBlobDetector> blob=SimpleBlobDetector::create();//默认参数创建
    //*blob检测
    vector<KeyPoint> key_points;
    blob->detect(src,key_points);
    Mat outImg;
    //*绘制结果
    drawKeypoints(src,key_points,outImg,Scalar(0,0,255));
    imshow("blob",outImg);

    waitKey();
    return 0;
}