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[OpenCV学习笔记]获取鼠标处图像的坐标和像素值

news 来源：原创 2024/5/1 13:52:48

1、介绍

实现获取鼠标点击处的图像的坐标和像素值，灰度图显示其灰度值，RGB图显示rgb的值。
OpenCV获取灰度值及彩色像素值的方法：

//灰度图像：
image.at<uchar>(j, i) //j为行数，i为列数
//BGR彩色图像
image.at<Vec3b>(j, i)[0] //B分量
image.at<Vec3b>(j, i)[1] //G分量
image.at<Vec3b>(j, i)[2] //R分量

这里要通过鼠标点击事件来获取鼠标点击的位置和状态，选择OpenCV的setMouseCallback回调函数实现。

2、效果展示

3、代码实现

onMouse.h

#ifndef ONMOUSE_H
#define ONMOUSE_H#include<iostream>
#include<opencv2/opencv.hpp>using namespace cv;
using namespace std;void onMouse(int event, int x, int y, int flags, void* param);  //evnet:鼠标事件类型 x,y:鼠标坐标 flags：鼠标哪个键void onMouse(int event, int x, int y, int flags, void* param)  //evnet:鼠标事件类型 x,y:鼠标坐标 flags：鼠标哪个键
{Mat* im = reinterpret_cast<Mat*>(param);switch (event) {case EVENT_LBUTTONDOWN://显示图像像素值if (static_cast<int>(im->channels()) == 1){//若图像为单通道图像，则显示鼠标点击的坐标以及灰度值switch (im->type()){case 0:cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<uchar>(Point(x, y))) << endl; break;case 1:cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<char>(Point(x, y))) << endl; break;case 2:cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<ushort>(Point(x, y))) << endl; break;case 3:cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<short>(Point(x, y))) << endl; break;case 4:cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<int>(Point(x, y))) << endl; break;case 5:cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<float>(Point(x, y))) << endl; break;case 6:cout << "at (" << x << ", " << y << " ) value is: " << static_cast<int>(im->at<double>(Point(x, y))) << endl; break;}}else{//若图像为彩色图像，则显示鼠标点击坐标以及对应的B, G, R值cout << "at (" << x << ", " << y << ")"<< "  B value is: " << static_cast<int>(im->at<Vec3b>(Point(x, y))[0])<< "  G value is: " << static_cast<int>(im->at<Vec3b>(Point(x, y))[1])<< "  R value is: " << static_cast<int>(im->at<Vec3b>(Point(x, y))[2])<< endl;}break;}
}
#endif // ONMOUSE_H

头文件onMouse.h主要实现鼠标点击事件的回调，输出点击时鼠标的坐标和对应的像素值。

main.cpp

    Mat image1 = imread("lena.png");if(image1.empty()){qDebug()<<"读取图像错误";}imshow("image1",image1);setMouseCallback("image1", onMouse, reinterpret_cast<void*>(&image1));

这里我用的Qt来实现的，要在pro文件里添加OpenCV库的引用

win32:CONFIG(release, debug|release): LIBS += -LD:/opencv/build/x64/vc15/lib/ -lopencv_world455
else:win32:CONFIG(debug, debug|release): LIBS += -LD:/opencv/build/x64/vc15/lib/ -lopencv_world455d
else:unix: LIBS += -LD:/opencv/build/x64/vc15/lib/ -lopencv_world455INCLUDEPATH += D:/opencv/build/include
DEPENDPATH += D:/opencv/build/include