Opencv之像素值的获取

　　灰度图像${\rm{M}} \times {\rm{N}}$的像素矩阵值为0~255，像素值越大越亮。${{\rm{I}}_{{\rm{i}}{\rm{j}}}}$,i表示行的位置，j 表示列的位置即i行j列。RGB图像在Opencv中内存顺序为：BGR三个通道。

获取像素的方式有三种：代码如下

 #include<opencv2/opencv.hpp>
 #include<iostream>

 using namespace std;
 using namespace cv;
 void point(Mat& inputImage, Mat& result, int div);//指针方式
 void iteraton_operate(Mat& inputImage, Mat& result, int div);//迭代器方式
 void dynamic_address(Mat& inputImage, Mat& result, int div);//动态地址方式
 Mat src, gray, dst;
 int main(int argc, char** argv)
 {

     src = imread("H:/cv_code/image/home.jpg");
     if (src.empty())
     {
         printf("could not find image");
         return -;
     }
     namedWindow("input");
     imshow("input",src);
     cvtColor(src,gray,COLOR_BGR2GRAY);
     namedWindow("result");
     point(src, dst, );
     iteraton_operate(src, dst, );
     dynamic_address(src, dst, );
     waitKey();
     return ;
 }
 void point(Mat& inputImage, Mat& result, int div)
 {
     result = inputImage.clone();
     int channels = result.channels();
     int rows = result.rows;
     int cols = result.cols * channels;
     for (int i = ; i < rows; i++)
     {
         uchar* value = result.ptr<uchar>(i);
         for (int j = ; j < cols; j++)
         {
             value[j] = value[j] / div * div + div / ;
         }
     }
 }
 void iteraton_operate(Mat& inputImage, Mat& result, int div)
 {
     result = inputImage.clone();
     Mat_<Vec3b>::iterator itbegin = result.begin<Vec3b>();
     Mat_<Vec3b>::iterator itend = result.end<Vec3b>();
     for (;itbegin !=itend;++itbegin)
     {
         (*itbegin)[] = (*itbegin)[] / div * div + div / ;
         (*itbegin)[] = (*itbegin)[] / div * div + div / ;
         (*itbegin)[] = (*itbegin)[] / div * div + div / ;

     }

 }
 void dynamic_address(Mat& inputImage, Mat& result, int div)
 {
     result = inputImage.clone();
     int rows = result.rows;
     int cols = result.cols;
     for (int i = ; i < rows; i++)
     {

         for (int j = ; j < cols; j++)
         {
             result.at<Vec3b>(i, j)[] = result.at<Vec3b>(i, j)[] / div * div + div / ;
             result.at<Vec3b>(i, j)[] = result.at<Vec3b>(i, j)[] / div * div + div / ;
             result.at<Vec3b>(i, j)[] = result.at<Vec3b>(i, j)[] / div * div + div / ;
         }
     }
 }