opencv学习之路(2)：图像像素的衰减和ptr，iterator的使用

#include <iostream>
#include "opencv2/opencv.hpp"
using namespace std;
void colorReduce(cv::Mat &image,int div=64)
{
    int rows =image.rows;
    int n = image.cols*image.channels();
    cout<<"rows"<<rows<<"channels:"<<n<<endl;
    for(int i=0;i<rows;i++)
    {
        uchar* data=image.ptr<uchar>(i);
        for(int j=0;j<n;j++)
        {
            data[j]=data[j]/div*div+div/2;
        }
    }
}
void colorReduce(cv::Mat &imageIn,cv::Mat &imageOut,int div=64)
{
    imageOut.create(imageIn.rows,imageIn.cols,imageIn.type());
    if(imageOut.channels() ==3)
    {
        cv::MatIterator_<cv::Vec3b> itbegin=imageOut.begin<cv::Vec3b>();
        cv::MatIterator_<cv::Vec3b> itend=imageOut.end<cv::Vec3b>();
        for( ;itbegin != itend;++itbegin)
        {
            (*itbegin)[0] =(*itbegin)[0]/div*div+div/2;
            (*itbegin)[1] =(*itbegin)[1]/div*div+div/2;
            (*itbegin)[2] =(*itbegin)[2]/div*div+div/2;
        }
    }
}
int main()
{
    cv::Mat matImage =cv::imread("E:/QtMaterial/images/boldt.jpg",1);//0: load pic in gray
    cv::Mat matBackImage =matImage.clone();
    colorReduce(matBackImage,64);
    cv::imshow("Process1",matBackImage);
    cv::imshow("Image",matImage);
    colorReduce(matImage,matImage,64);
    cv::imshow("Process2",matImage);
    cv::waitKey();
    return 0;
}

　　at的使用例程

#include <iostream>
#include "opencv2/opencv.hpp"
#include "math.h"

using namespace std;
/* add salt
 *@image:   source image
 *@n:   the number of salt
 */
void salt(cv::Mat &image,int n)
{
    for(int k=0;k<n;k++)
    {
        int i=rand()%image.cols;
        int j=rand()%image.rows;
        if(image.channels()==1)
        {
            image.at<char>(j,i)=255;
        }
        if(image.channels()==3)
        {
        image.at<cv::Vec3b>(j,i)[0] = 255;
        image.at<cv::Vec3b>(j,i)[1] = 255;
        image.at<cv::Vec3b>(j,i)[2] = 255;
        }
    }
}
int main()
{
    cv::Mat image =cv::imread("E:/QtMaterial/images/boldt.jpg");//OR ("E:\QtMaterial\images\boldt.jpg");
    salt(image,30000);//200*292=60000
    cv::namedWindow("Image with salt");
    cv::imshow("Image with salt",image);
    cv::waitKey();
    return 0;
}