OpenCV4入门教程103：形态学滤波实现角点检测

角点和角点检测：角点检测

使用形态学操作实现角点检测

// 功能：代码 6-5 形态学滤波实现角点检测
// 作者：朱伟 zhu1988wei@163.com
// 来源：《OpenCV图像处理编程实例》
// 博客：http://blog.csdn.net/zhuwei1988
// 更新：2016-8-1
// 说明：版权所有，引用或摘录请联系作者，并按照上面格式注明出处，谢谢。// 
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
using namespace cv;
int main()
{
    cv::Mat srcImage = cv::imread("..\\images\\sea.jpg");
    if (!srcImage.data)
        return 1;
    cv::Mat srcGray;
    cv::cvtColor(srcImage, srcGray, CV_RGB2GRAY);
    // 定义结构元素
    Mat CrossMat(5, 5, CV_8U, Scalar(0));
    Mat diamondMat(5, 5, CV_8U, Scalar(1));
    Mat squareMat(5, 5, CV_8U, Scalar(1));
    Mat x(5, 5, CV_8U, Scalar(0));
    //  十字形形状  
    for (int i = 0; i<5; i++)
    {
        CrossMat.at<uchar>(2, i) = 1;
        CrossMat.at<uchar>(i, 2) = 1;
    }
    // 菱形形状
    diamondMat.at<uchar>(0, 0) = 0;
    diamondMat.at<uchar>(0, 1) = 0;
    diamondMat.at<uchar>(1, 0) = 0;
    diamondMat.at<uchar>(4, 4) = 0;
    diamondMat.at<uchar>(3, 4) = 0;
    diamondMat.at<uchar>(4, 3) = 0;
    diamondMat.at<uchar>(4, 0) = 0;
    diamondMat.at<uchar>(4, 1) = 0;
    diamondMat.at<uchar>(3, 0) = 0;
    diamondMat.at<uchar>(0, 4) = 0;
    diamondMat.at<uchar>(0, 3) = 0;
    diamondMat.at<uchar>(1, 4) = 0;
    // X形状
    for (int i = 0; i<5; i++){
        x.at<uchar>(i, i) = 1;
        x.at<uchar>(4 - i, i) = 1;
    }
    // 第1步：十字形对原图进行膨胀
    Mat result;
    dilate(srcGray, result, CrossMat);
    // 第2步：菱形对上步进行腐蚀
    erode(result, result, diamondMat);
    Mat result2;
    // 第3步：X形对原图进行腐蚀
    dilate(srcGray, result2, x);
    // 第4步：正方形对上步进行腐蚀
    erode(result2, result2, squareMat);
    // 第4步：计算差值
    absdiff(result2, result, result);
    threshold(result, result, 40, 255, THRESH_BINARY);
    // 绘图
    for (int i = 0; i < result.rows; i++)
    {
        // 获取行指针
        const uchar* data = result.ptr<uchar>(i);
        for (int j = 0; j < result.cols; j++)
        {
            // 如果是角点 则进行绘制圆圈
            if (data[j])
               circle(srcImage, Point(j, i), 8, 
                Scalar(0, 255, 0));
        }
    }
    cv::imshow("result", result);
    cv::imshow("srcImage", srcImage);
    cv::waitKey(0);
    return 0;
}