OpenCV Mat图像的像素值读写

由于需要将raw格式的16位单通道图像数据读入后，转成8位进行画图，用到了opencv的Mat格式，因此需要将读入后的图像数据数组，赋值给Mat，然后imshow出来，但是需要同时在图像上进行画有颜色的矩形框，因此需要赋值给三通道的Mat,因此搜索了Mat的像素值的赋值与读取。
主要用到的语法为opencv Mat的像素值的访问：

Mat image;
image.at<存储类型名称>(行，列)[通道]

对于单通道的灰度图像，可以使用

image.at<uchar>(i, j)

对于RGB图像，可以使用

image.at<Vec3b>(i, j)[0]  
image.at<Vec3b>(i, j)[1]  
image.at<Vec3b>(i, j)[2]

1.数组赋值给gray的Mat

unsigned short array0[IMGSIZE];// = imread("office.jpg",0);
	Mat read0(ROW, COL, CV_8UC1, Scalar(100));
	uchar* pxvec;

	for (i = 0; i < ROW; i++)
	{
    
    
		for (j = 0; j < COL; j++)
		{
    
    
			*(array0 + i * COL + j) = i + j;
		}
	}
	//数值复制给Mat
	for (i = 0; i < ROW; i++)
	{
    
    
		pxvec = read0.ptr<uchar>(i);
		for (j = 0; j < COL; j++)
		{
    
    
			pxvec[j] = *(array0 + i*COL + j) / 2;
			//read.at<uchar>(i,j) = *(img11 + i*COL + j)/2;
		}
	}
	cv::rectangle(read0, cv::Point(100, 50), cv::Point(100 + 20 - 1, 50 + 20 - 1), cv::Scalar(0, 255, 0), 2, 8, 0);
	namedWindow("fig", CV_WINDOW_AUTOSIZE);
	imshow("fig", read0);
	waitKey(0);

2.RGB图像复制给RGB的Mat

图和框都是彩色的

Mat read = imread("office.jpg");
	Mat img(read.rows, read.cols, CV_8UC3, Scalar(0, 255, 0));
	for (int j = 0; j < read.rows; j++)
	{
    
    
		for (int k = 0; k < read.cols; k++)
		{
    
    
			img.at<Vec3b>(j, k)[0] = read.at<Vec3b>(j, k)[0];
			img.at<Vec3b>(j, k)[1] = read.at<Vec3b>(j, k)[1];
			img.at<Vec3b>(j, k)[2] = read.at<Vec3b>(j, k)[2];
		}
	}
	cv::rectangle(img, cv::Point(100, 50), cv::Point(100 + 20 - 1, 50 + 20 - 1), cv::Scalar(0, 255, 0), 2, 8, 0);
	namedWindow("fig", CV_WINDOW_AUTOSIZE);
	imshow("fig", img);
	waitKey(0);

3.Gray图像复制给RGB的Mat

三个通道的图像都是一样的

Mat read_gray = imread("office.jpg", IMREAD_GRAYSCALE);
	Mat img_rbg(read_gray.rows, read_gray.cols, CV_8UC3, Scalar(0, 255, 0));
	for (int j = 0; j < read_gray.rows; j++)
	{
    
    
		for (int k = 0; k < read_gray.cols; k++)
		{
    
    
			img_rbg.at<Vec3b>(j, k)[0] = read_gray.at<uchar>(j, k);
			img_rbg.at<Vec3b>(j, k)[1] = read_gray.at<uchar>(j, k);
			img_rbg.at<Vec3b>(j, k)[2] = read_gray.at<uchar>(j, k);
		}
	}
	cv::rectangle(img_rbg, cv::Point(100, 50), cv::Point(100 + 20 - 1, 50 + 20 - 1), cv::Scalar(0, 255, 0), 2, 8, 0);
	namedWindow("fig", CV_WINDOW_AUTOSIZE);
	imshow("fig", img_rbg);
	waitKey(0);

4.Gray图像复制给gray的Mat

画出的矩形框也是不带颜色的灰框

Mat img_gray(read_gray.rows, read_gray.cols, CV_8UC1, Scalar(100));
	for (int j = 0; j < read_gray.rows; j++)
	{
    
    
		for (int k = 0; k < read_gray.cols; k++)
		{
    
    
			img_gray.at<uchar>(j, k) = read_gray.at<uchar>(j, k);
			img_gray.at<uchar>(j, k) = read_gray.at<uchar>(j, k);
			img_gray.at<uchar>(j, k) = read_gray.at<uchar>(j, k);
		}
	}
	/*img.ptr<uchar>(0)[0] = 0;
	img.ptr<uchar>(0)[1] = 0;
	img.ptr<uchar>(0)[2] = 255;*/
	cv::rectangle(img_gray, cv::Point(100, 50), cv::Point(100 + 20 - 1, 50 + 20 - 1), cv::Scalar(0, 255, 0), 2, 8, 0);
	namedWindow("fig", CV_WINDOW_AUTOSIZE);
	imshow("fig", img_gray);
	waitKey(0);

完整代码

#include<iostream>
#include<opencv2\opencv.hpp>
//#include<opencv2\highgui\highgui.hpp>
using namespace std;
using namespace cv;
#define ROW 256
#define COL 256
#define IMGSIZE ROW*COL
int main()
{
    
    
	int i, j;
	

	//1.灰度图像赋值给gray的Mat；
	//数组赋值
unsigned short array0[IMGSIZE];// = imread("office.jpg",0);
	Mat read0(ROW, COL, CV_8UC1, Scalar(100));
	uchar* pxvec;

	for (i = 0; i < ROW; i++)
	{
    
    
		for (j = 0; j < COL; j++)
		{
    
    
			*(array0 + i * COL + j) = i + j;
		}
	}
	//数值复制给Mat
	for (i = 0; i < ROW; i++)
	{
    
    
		pxvec = read0.ptr<uchar>(i);
		for (j = 0; j < COL; j++)
		{
    
    
			pxvec[j] = *(array0 + i*COL + j) / 2;
			//read.at<uchar>(i,j) = *(img11 + i*COL + j)/2;
		}
	}
	cv::rectangle(read0, cv::Point(100, 50), cv::Point(100 + 20 - 1, 50 + 20 - 1), cv::Scalar(0, 255, 0), 2, 8, 0);
	namedWindow("fig", CV_WINDOW_AUTOSIZE);
	imshow("fig", read0);
	waitKey(0);
	//2.RGB图像复制给RGB的Mat
	Mat read = imread("office.jpg");
	Mat img(read.rows, read.cols, CV_8UC3, Scalar(0, 255, 0));
	for (int j = 0; j < read.rows; j++)
	{
    
    
		for (int k = 0; k < read.cols; k++)
		{
    
    
			img.at<Vec3b>(j, k)[0] = read.at<Vec3b>(j, k)[0];
			img.at<Vec3b>(j, k)[1] = read.at<Vec3b>(j, k)[1];
			img.at<Vec3b>(j, k)[2] = read.at<Vec3b>(j, k)[2];
		}
	}
	cv::rectangle(img, cv::Point(100, 50), cv::Point(100 + 20 - 1, 50 + 20 - 1), cv::Scalar(0, 255, 0), 2, 8, 0);
	namedWindow("fig", CV_WINDOW_AUTOSIZE);
	imshow("fig", img);
	waitKey(0);
	//Gray图像复制给RGB的Mat
	Mat read_gray = imread("office.jpg", IMREAD_GRAYSCALE);
	Mat img_rbg(read_gray.rows, read_gray.cols, CV_8UC3, Scalar(0, 255, 0));
	for (int j = 0; j < read_gray.rows; j++)
	{
    
    
		for (int k = 0; k < read_gray.cols; k++)
		{
    
    
			img_rbg.at<Vec3b>(j, k)[0] = read_gray.at<uchar>(j, k);
			img_rbg.at<Vec3b>(j, k)[1] = read_gray.at<uchar>(j, k);
			img_rbg.at<Vec3b>(j, k)[2] = read_gray.at<uchar>(j, k);
		}
	}
	cv::rectangle(img_rbg, cv::Point(100, 50), cv::Point(100 + 20 - 1, 50 + 20 - 1), cv::Scalar(0, 255, 0), 2, 8, 0);
	namedWindow("fig", CV_WINDOW_AUTOSIZE);
	imshow("fig", img_rbg);
	waitKey(0);
	//Gray图像复制给gray的Mat
	Mat img_gray(read_gray.rows, read_gray.cols, CV_8UC1, Scalar(100));
	for (int j = 0; j < read_gray.rows; j++)
	{
    
    
		for (int k = 0; k < read_gray.cols; k++)
		{
    
    
			img_gray.at<uchar>(j, k) = read_gray.at<uchar>(j, k);
			img_gray.at<uchar>(j, k) = read_gray.at<uchar>(j, k);
			img_gray.at<uchar>(j, k) = read_gray.at<uchar>(j, k);
		}
	}
	/*img.ptr<uchar>(0)[0] = 0;
	img.ptr<uchar>(0)[1] = 0;
	img.ptr<uchar>(0)[2] = 255;*/
	cv::rectangle(img_gray, cv::Point(100, 50), cv::Point(100 + 20 - 1, 50 + 20 - 1), cv::Scalar(0, 255, 0), 2, 8, 0);
	namedWindow("fig", CV_WINDOW_AUTOSIZE);
	imshow("fig", img_gray);
	waitKey(0);
	destroyWindow("fig");
	return 0;
}