使用本代码可以打印出鼠标所在的坐标和像素大小（黑白图片）
使用函数setMouseCallback，输入参数1是窗口名字，输入参数2是调用的函数。
语言是C++，OpenCV版本是3.1.0。

#include "opencv2/core.hpp"
#include <opencv2/core/utility.hpp>
#include "opencv2/imgproc.hpp"
#include "opencv2/calib3d.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/videoio.hpp"
#include "opencv2/highgui.hpp"
 
#include<iostream>
 
using namespace cv;
using namespace std;
 
void OnMouseAction(int event,int x,int y,int flags,void *ustc);  //鼠标回调事件函数
int static times; //记录调用次数
 
Mat  image;
 
int main(int argc,char*argv[])
{
    image=imread("left01.jpg", IMREAD_GRAYSCALE);
    imshow("image",image);
    setMouseCallback("image",OnMouseAction);
    waitKey();
    system("pause");
}
 
//*******************************************************************//
//鼠标回调函数
 
void OnMouseAction(int event,int x,int y,int flags,void *ustc)
{   
    //cout<<"第 "<<times<<" 次回调鼠标事件"<<endl;
 
    if(event==CV_EVENT_LBUTTONDOWN)
    {
        cout<<"触发左键按下事件"<<endl;
        cout<<"location: "<<x<<", "<<y<<endl;
 
        unsigned char* row_ptr = image.ptr<unsigned char> ( y );  // row_ptr是第y行的头指针
        unsigned char* data_ptr = &row_ptr[ x*image.channels() ]; // data_ptr 指向待访问的像素数据
        // 输出该像素的每个通道,如果是灰度图就只有一个通道
        for ( int c = 0; c != image.channels(); c++ )
        {
            unsigned char data = data_ptr[c]; // data为I(x,y)第c个通道的值
            cout << (int)data << endl;
        }       
    }
    /*
    if(event==CV_EVENT_MOUSEMOVE)
    {
        cout<<"触发鼠标移动事件"<<endl;
    }
    if(event==CV_EVENT_LBUTTONUP)
    {
        cout<<"触发左键抬起事件"<<endl;
    }
    if(event==CV_EVENT_RBUTTONDOWN)
    {
        cout<<"触发右键按下事件"<<endl;
    }
    if(event==CV_EVENT_RBUTTONUP)
    {
        cout<<"触发右键抬起事件"<<endl;
    }
    if(event==CV_EVENT_LBUTTONDBLCLK)
    {
        cout<<"触发左键双击事件"<<endl;
    }
    if(event==CV_EVENT_RBUTTONDBLCLK)
    {
        cout<<"触发右键双击事件"<<endl;
    }*/
}