《Opencv入门》指针遍历

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

using namespace std;
using namespace cv;

int main(int argc, char* argv[])
{
	Mat grayim(600, 800, CV_8UC1);
	Mat colorim(600, 800, CV_8UC3);

	//遍历所有像素，并设置像素值 
	for (int i = 0; i < grayim.rows; ++i)
	{
		//获取第 i行首像素指针 
		uchar * p = grayim.ptr<uchar>(i);
		//对第i 行的每个像素(byte)操作 
		for (int j = 0; j < grayim.cols; ++j)
			p[j] = (i + j) % 255;
	}
	//遍历所有像素，并设置像素值 
	for (int i = 0; i < colorim.rows; ++i)
	{
		//获取第 i行首像素指针 
		Vec3b * p = colorim.ptr<Vec3b>(i);
		for (int j = 0; j < colorim.cols; ++j)
		{
			p[j][0] = i % 255; //Blue 
			p[j][1] = j % 255; //Green 
			p[j][2] = 0;     //Red 
		}
	}

	//显示结果 
	imshow("grayim", grayim);
	imshow("colorim", colorim);
	waitKey(0);

	return 0;
}

注意：

//获取第 i行首像素指针 
		uchar * p = grayim.ptr<uchar>(i);

ptr的使用！！！！