opencv-109-BLOB特征分析(simpleblobdetector使用)

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知识点

BLOB是图像中灰度块的一种专业称呼，更加变通一点的可以说它跟我们前面二值图像分析的联通组件类似，通过特征提取中的SimpleBlobDetector可以实现常见的各种灰度BLOB对象组件检测与分离。使用该检测器的时候，可以根据需要输入不同参数，得到的结果跟输入的参数息息相关。常见的BLOB分析支持如下：

  • 根据BLOB面积过滤
  • 根据灰度/颜色值过滤
  • 根据圆度过滤
  • 根据长轴与短轴过滤
  • 根据凹凸进行过滤

参数列表

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SimpleBlobDetector::Params::Params()
bool 	filterByArea
bool 	filterByCircularity
bool 	filterByColor
bool 	filterByConvexity
bool 	filterByInertia
float 	maxArea
float 	maxCircularity
float 	maxConvexity
float 	maxInertiaRatio
float 	maxThreshold
float 	minArea
float 	minCircularity
float 	minConvexity
float 	minDistBetweenBlobs
float 	minInertiaRatio

代码（c++,python）

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

using namespace cv;
using namespace std;

int main(int argc, char** argv)
{
	// 加载图像
	Mat src = imread("D:/images/blob2.png");
	Mat gray;
	cvtColor(src, gray, COLOR_BGR2GRAY);

	// 初始化参数设置
	SimpleBlobDetector::Params params;
	params.minThreshold = 10;
	params.maxThreshold = 200;
	params.filterByArea = true;
	params.minArea = 100;
	params.filterByCircularity = true;
	params.minCircularity = 0.1;
	params.filterByConvexity = true;
	params.minConvexity = 0.87;
	params.filterByInertia = true;
	params.minInertiaRatio = 0.01;

	// 创建BLOB Detetor
	Ptr<SimpleBlobDetector> detector = SimpleBlobDetector::create(params);

	// BLOB分析与显示
	Mat result;
	vector<KeyPoint> keypoints;
	detector->detect(gray, keypoints);
	drawKeypoints(src, keypoints, result, Scalar(0, 0, 255), DrawMatchesFlags::DRAW_RICH_KEYPOINTS);
	imshow("Blob Detection Demo", result);
	waitKey(0);
}
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"""
BLOB特征分析(simpleblobdetector使用)
"""

import cv2 as cv

frame = cv.imread("images/zhifang_ball.png")
cv.imshow("input", frame)
gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
params = cv.SimpleBlobDetector_Params()

# change thresholds
params.minThreshold = 0
params.maxThreshold = 256

# filter by area
params.filterByArea = True
params.minArea = 100

# filter by circularity
params.filterByCircularity = True
params.minCircularity = 0.1

# Filter by Convexity
params.filterByConvexity = True
params.minConvexity = 0.5

# Filter by Inertia
params.filterByInertia = True
params.minInertiaRatio = 0.5

# 提取关键点
detector = cv.SimpleBlobDetector_create(params)
keypoints = detector.detect(gray)
for marker in keypoints:
    result = cv.drawMarker(frame, tuple(int(i) for i in marker.pt), color=(0, 255, 0))
cv.imshow("result", result)

cv.waitKey(0)
cv.destroyAllWindows()

结果

代码地址

github