#include<opencv2/opencv.hpp>#include<iostream>using namespace std;using namespace cv;void on_mouse(int EVENT, int x, int y, int flags, void* userdata);void main(){ namedWindow("【display】"); Mat src; src = imread("F://lena_rgb.jpg"); //cvtColor(src, src, COLOR_RGB2GRAY); setMouseCallback("【display】", on_mouse,&src); //以40ms刷新顯示 while (1) {  imshow("【display】", src);  waitKey(40); }}void on_mouse(int EVENT, int x, int y, int flags, void* userdata) {  Mat hh;  hh = *(Mat*)userdata;  Point p(x, y);  switch (EVENT)  {   case EVENT_LBUTTONDOWN:   {    printf("b=%d/t", hh.at<Vec3b>(p)[0]);    printf("g=%d/t", hh.at<Vec3b>(p)[1]);    printf("r=%d/n", hh.at<Vec3b>(p)[2]);    circle(hh, p, 2, Scalar(255),3);   }   break;  } }