opencv_找cv::Mat中的最大值和最小值

﹏ヽ暗。殇╰゛Y 2022-11-22 10:29 209阅读 0赞

# 方法1: std 中 algorithm #

#include <iostream>     // std::cout
    #include <algorithm>    // std::min_element, std::max_element
    
    cv::Mat img = cv::imread("path-to-image/juice.tiff");
    
    // 假设图片数据类型位float
    float maxValue = *max_element(img.begin<float>(), img.end<float>());
    float minValue = *min_element(img.begin<float>(), img.end<float>());

# 方法2: cv中minMaxLoc #

#include <iostream>
    #include <opencv2/opencv.hpp>
    
    int main()
    {
        // std::cout << "Hello World!\n";
        cv::Mat image = cv::imread("path-to-image/juice.png");
        cv::Mat image_re = image.reshape(1);
        double minValue, maxValue;    // 最大值，最小值
        cv::Point  minIdx, maxIdx;    // 最小值坐标，最大值坐标     
        cv::minMaxLoc(image_re, &minValue, &maxValue, &minIdx, &maxIdx);
        std::cout << "最大值：" << maxValue <<"最小值："<<minValue<<std::endl;
        std::cout << "最大值位置：" << maxIdx << "最小值位置：" << minIdx;
       
        cv::waitKey(0);
    
    }

# 方法3: 遍历Mat #

#include <iostream>
    #include <cstdlib>
    #include <cmath>
    #include <iomanip>
    #include <algorithm>
     
    #include "opencv2/core/core.hpp"
    #include "opencv2/highgui/highgui.hpp"
    #include "opencv2/imgproc/imgproc.hpp"
    #include "opencv2/contrib/contrib.hpp"
     
    using namespace std;
    using namespace cv;
     
    int main(int argc, char* argv[])
    {
    #pragma region min_max
     
    	float Tval = 0.0;
    	float RawData[2][3] = {
       {4.0,1.0,3.0},{8.0,7.0,9.0}};
    	Mat RawDataMat(2,3,CV_32FC1,RawData);
     
    	for (int j = 0; j < 2; j++)
    	{
    		for (int i = 0; i < 3; i++)
    		{	
    			//Tval = RawData[j][i];             //No problem !!!
    			Tval = RawDataMat.at<float>(j,i);
    			cout << "(j,i) = "<<j<<","<<i<<"\t"<<Tval<<endl;
    		}
    	}
     
    	double minv = 0.0, maxv = 0.0;
    	double* minp = &minv;
    	double* maxp = &maxv;
     
    	minMaxIdx(RawDataMat,minp,maxp);
     
    	cout << "Mat minv = " << minv << endl;
    	cout << "Mat maxv = " << maxv << endl;
     
    #pragma endregion
     
    	return 0;
    }

# 参考: #

*  [OpenCV 找出图像中最小值最大值函数minMaxLoc的使用][OpenCV _minMaxLoc]
 *  [opencv Mat 数据 最大值和最小值][opencv Mat _]

[OpenCV _minMaxLoc]: https://blog.csdn.net/jndingxin/article/details/108447110?utm_medium=distribute.pc_aggpage_search_result.none-task-blog-2~all~first_rank_v2~rank_v28-3-108447110.nonecase&utm_term=mat%E7%9A%84%E6%9C%80%E5%A4%A7%E5%80%BC%E5%92%8C%E6%9C%80%E5%B0%8F%E5%80%BC%20opencv&spm=1000.2123.3001.4430
[opencv Mat _]: https://blog.csdn.net/tianzhaixing2013/article/details/21390505