opencv中ptr的使用

#include <QCoreApplication>
#include<stdio.h>
#include<opencv2/highgui/highgui.hpp>
#include<opencv2/core/core.hpp>
using namespace cv;
void colorReduce(Mat &image,int div =){
    int nl = image.rows;
    int nc =image.cols*image.channels();
    for(int j =;j<nl;j++ )
    {
        uchar* data = image.ptr<uchar>(j);//最需要注意的就是这行代码的使用
        for(int i=;i<nc;i++)
        {
             qDebug("the first data[i] is %d",data[i]);
             data[i] = data[i]/div*div ;
             /**************************

             另外此处还可以如此 使用uchar *data = image.ptr<uchar>(j)[i];
             这种方式更加经典，执行效率更高

             ********************************/
             qDebug("the second data[i] is %d",data[i]);

// data[i] = data[i]/(div*div)+ div/2;

// data[i] = data[i]%div+ div/2;
         //   data[i] = data[i] + div/2;
        }
    }

}
int main()
{
    Mat image1;
    image1 = imread("/home/bi/pic/mei.jpg");
    namedWindow("image1");
    imshow("image1",image1);
   namedWindow("colorReduce");
   colorReduce(image1);
    //QCoreApplication a(argc, argv);
   imshow("colorReduce",image1);
   waitKey();
   return ;
    //return a.exec();
}

 template<typename _Tp> class Ptr
 {
 public:
 // default constructor
 Ptr();
 // constructor that wraps the object pointer
 Ptr(_Tp* _obj);
 // destructor: calls release()
 ~Ptr();
 // copy constructor; increments ptr’s reference counter
 Ptr(const Ptr& ptr);
 // assignment operator; decrements own reference counter
 // (with release()) and increments ptr’s reference counter
 Ptr& operator = (const Ptr& ptr);
 // increments reference counter
 void addref();