OpenCV.2.Computer.Vision.Application.Programming.Cookbook--Accessing pixel values

#include<opencv2\opencv.hpp>

void salt(cv::Mat &image, int n)
{
	for (int k=0; k<n; k++) 
	{
		// rand() is the MFC random number generator
		int i= rand()%image.cols;
		int j= rand()%image.rows;
		if (image.channels() == 1) 
		{ 
			// gray-level image
			image.at<uchar>(j,i)= 255;
		} 
		else if (image.channels() == 3)
		{ 
			// color image
			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(int argc,char* argv[])
{
	cv::Mat pImg;

	pImg=cv::imread("lena.jpg");
	cv::namedWindow("Image");
	cv::imshow("Image",pImg);

	salt(pImg,300);
	
	cv::namedWindow("pImg");
	cv::imshow("pImg",pImg);

	cv::waitKey(0);

	cv::destroyWindow("Image");
	return 0;
}