该代码通过鼠标选取左上角和右下角两个点，并基于这两个点实现ROI区域的选取，ROI区域内所有像素值被赋予左上角选取点的像素值。
源代码
#include <opencv2/core/core.hpp> #include <opencv2/highgui/highgui.hpp> #include <stdio.h> #include<opencv.hpp>#include<cmath>using namespace cv;using namespace std;cv::Mat org_, dst_, img_, tmp_;int pointValue;void on_mouse(int event, int x, int y, int flags, void *ustc)//event鼠标事件代号，x,y鼠标坐标，flags拖拽和键盘操作的代号 {static Point pre_pt = (-1, -1);//初始坐标 static Point cur_pt = (-1, -1);//实时坐标 char temp[16];if (event == CV_EVENT_LBUTTONDOWN)//左键按下，读取初始坐标，并在图像上该点处划圆 {pointValue=0;org_.copyTo(img_);//将原始图片复制到img中 cout << img_.rows << " " << img_.cols << endl;sprintf(temp, "(%d,%d)", x, y);pre_pt = Point(x, y);pointValue = img_.at<Vec3b>(pre_pt)[0];cout << pointValue<<endl;/* cout << org.at<Vec3b>(pre_pt)[1];cout << org.at<Vec3b>(pre_pt)[2];*///初始坐标//putText(org_, temp, pre_pt, FONT_HERSHEY_SIMPLEX, 0.5, Scalar(0, 0, 0, 255), 1, 8);//在窗口上显示坐标 //circle(org_, pre_pt, 2, Scalar(255, 0, 0, 0), CV_FILLED, CV_AA, 0);//划圆 imshow("img", org_);}else if (event == CV_EVENT_MOUSEMOVE && !(flags & CV_EVENT_FLAG_LBUTTON))//左键没有按下的情况下鼠标移动的处理函数 {img_.copyTo(tmp_);//将img复制到临时图像tmp上，用于显示实时坐标 sprintf(temp, "(%d,%d)", x, y);cur_pt = Point(x, y);//putText(org_, temp, cur_pt, FONT_HERSHEY_SIMPLEX, 0.5, Scalar(0, 0, 0, 255));//只是实时显示鼠标移动的坐标 imshow("img", org_);}else if (event == CV_EVENT_MOUSEMOVE && (flags & CV_EVENT_FLAG_LBUTTON))//左键按下时，鼠标移动，则在图像上划矩形 {img_.copyTo(tmp_);sprintf(temp, "(%d,%d)", x, y);cur_pt = Point(x, y);//putText(org_, temp, cur_pt, FONT_HERSHEY_SIMPLEX, 0.5, Scalar(0, 0, 0, 255));rectangle(tmp_, pre_pt, cur_pt, Scalar(0, 255, 0, 0), 1, 8, 0);//在临时图像上实时显示鼠标拖动时形成的矩形 imshow("img", tmp_);}else if (event == CV_EVENT_LBUTTONUP)//左键松开，将在图像上划矩形 {org_.copyTo(img_);sprintf(temp, "(%d,%d)", x, y);cur_pt = Point(x, y);int height_ = abs(cur_pt.x - pre_pt.x);int width_ = abs(cur_pt.y - pre_pt.y);//Mat imageBlue, imageGreen, imageRed;Mat imageBlue = Mat::zeros(img_.rows, img_.cols, CV_8UC1);Mat imageGreen = Mat::zeros(img_.rows, img_.cols, CV_8UC1);Mat imageRed = Mat::zeros(img_.rows, img_.cols, CV_8UC1);Mat mergeImage;Mat test0,test1,test2;vector<Mat> channelrgb;Mat mer;//putText(org_, temp, cur_pt, FONT_HERSHEY_SIMPLEX, 0.5, Scalar(0, 0, 0, 255));//circle(org_, pre_pt, 2, Scalar(255, 0, 0, 0), CV_FILLED, CV_AA, 0);split(img_, channelrgb);imageBlue = channelrgb.at(0);imageGreen = channelrgb.at(1);imageRed = channelrgb.at(2);cout << imageRed.rows<<" "<<imageRed.cols<< endl;if ((cur_pt.x > pre_pt.x) && (cur_pt.y > pre_pt.y)){for (int i = 0; i < (cur_pt.x - pre_pt.x); i++){for (int j = 0; j <(cur_pt.y - pre_pt.y); j++){imageBlue.at<uchar>(j + pre_pt.y, i + pre_pt.x) = pointValue;imageGreen.at<uchar>(j + pre_pt.y, i + pre_pt.x) = pointValue;imageRed.at<uchar>(j + pre_pt.y, i + pre_pt.x) = pointValue;}}}channelrgb.at(0) = imageBlue;channelrgb.at(1) = imageGreen;channelrgb.at(2) = imageRed;test0 = channelrgb.at(0);test1 = channelrgb.at(1);test2 = channelrgb.at(2);merge(channelrgb, org_);cout << "cui" << endl;//截取矩形包围的图像，并保存到dst中 int width = abs(pre_pt.x - cur_pt.x);int height = abs(pre_pt.y - cur_pt.y);if (width == 0 || height == 0){printf("width == 0 || height == 0");return;}dst_ = org_(Rect(min(cur_pt.x, pre_pt.x), min(cur_pt.y, pre_pt.y), width, height));//namedWindow("merge", 0);//imshow("merge", org_);imwrite("C:\\Users\\new\\Desktop\\test.bmp", org_);waitKey(0);}}void main(){org_ = imread("C:/Users/new/Desktop/1.bmp");namedWindow("img",0);//定义一个img窗口 setMouseCallback("img", on_mouse, 0);//调用回调函数 //imshow("img", img_);cv::waitKey(0);}
