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 =64){
int nl = image.rows;
int nc =image.cols*image.channels();
for(int j =0;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=0;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 0;
//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();