原图1：

原图2：

 合并后效果：

 代码如下：

#include<iostream>
#include<opencv2/opencv.hpp>
using namespace cv;
using namespace std;
int main(int argc, char** argv)
{
	Mat img1 = imread("D:/tupian/gril2.jpg");
	
	namedWindow("input image", CV_WINDOW_AUTOSIZE);
	imshow("input image", img1);

	Mat img2 = imread("D:/tupian/ruanbin.jpg");
	namedWindow("img2");
	imshow("img2", img2);
	int height = img1.rows;//随便设置一个图片的行为高
	int weight1 = img1.cols;
	int weight2 = img2.cols;
	if (img1.rows > img2.rows)
	{
		height = img2.rows;
		weight1 = img1.cols*((float)img2.rows/(float)img1.rows);//按比例缩小或放大
		resize(img1, img1, Size(weight1, height));

	}
	else if(img1.rows<img2.rows)
	{
		
		weight2 = img2.cols * ((float)img1.rows / (float)img2.rows);//同理
		resize(img2, img2, Size(weight2, height));
	}
	Mat des;
	des.create(height, weight1 + weight2, img1.type());//创建一新的图片用来放置两个图片的合并
	Mat r1 = des(Rect(0, 0, weight1, height));//将图片放在新创建的图片合适位置
	img1.copyTo(r1);//将图1复制到该区域
	Mat r2 = des(Rect(weight1, 0, weight2, height));
	img2.copyTo(r2);
	namedWindow("des");
	imshow("des", des);
	imwrite("D:/tupian/xiaoguo.jpg",des);
	waitKey(0);
	return 0;

}