图像拼接stitching是OpenCV2.4.0出现的一个新模块，所有的相关函数都被封装在Stitcher类当中。关于Stitcher类的详细介绍，可以参考： /2.4.2/modules/stitching/doc/high_level.html?highlight=stitcher#stitcher。
这个类当中我们主要用到的成员函数有createDefault，用于创建缺省参数的stitcher；estimateTransform，用于 生成最后的拼接图像；而对于composePanorama和stitch，文档中提示如果对stitching的整过过程不熟悉的话，最好不要使用以上 两个函数，直接使用stitch就行了。整个拼接的算法实现过程十分复杂，其中涉及到图像特征点的提取和匹配、摄像机的校准、图像融合、图像的变形、曝光 补偿等算法的结合。
说得这么复杂，但实际上这些模块的接口调用，OpenCV都为我们搞定了，我们只需要调用createDefault函数生成默认的参数，再使用stitch函数进行拼接就ok了。
图像拼接的实例代码如下，在VS平台上运行成功：
/*M/////////////////////////////////// IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.//// By downloading, copying, installing or using the software you agree to this license.// If you do not agree to this license, do not download, install,// copy or use the software.//////License Agreement//For Open Source Computer Vision Library//// Copyright (C) 2000-, Intel Corporation, all rights reserved.// Copyright (C) , Willow Garage Inc., all rights reserved.// Third party copyrights are property of their respective owners.//// Redistribution and use in source and binary forms, with or without modification,// are permitted provided that the following conditions are met://// * Redistribution's of source code must retain the above copyright notice,//this list of conditions and the following disclaimer.//// * Redistribution's in binary form must reproduce the above copyright notice,//this list of conditions and the following disclaimer in the documentation//and/or other materials provided with the distribution.//// * The name of the copyright holders may not be used to endorse or promote products//derived from this software without specific prior written permission.//// This software is provided by the copyright holders and contributors "as is" and// any express or implied warranties, including, but not limited to, the implied// warranties of merchantability and fitness for a particular purpose are disclaimed.// In no event shall the Intel Corporation or contributors be liable for any direct,// indirect, incidental, special, exemplary, or consequential damages// (including, but not limited to, procurement of substitute goods or services;// loss of use, data, or profits; or business interruption) however caused// and on any theory of liability, whether in contract, strict liability,// or tort (including negligence or otherwise) arising in any way out of// the use of this software, even if advised of the possibility of such damage.////M*/#include <iostream>#include <fstream>#include "opencv2/highgui/highgui.hpp"#include "opencv2/stitching/stitcher.hpp"using namespace std;using namespace cv;bool try_use_gpu = false; vector<Mat> imgs;string result_name = "result.jpg"; // 默认输出文件名及格式void printUsage();int parseCmdArgs(int argc, char** argv);int main(int argc, char* argv[]){int retval = parseCmdArgs(argc, argv);if (retval) return -1;Mat pano;Stitcher stitcher = Stitcher::createDefault(try_use_gpu);Stitcher::Status status = stitcher.stitch(imgs, pano);if (status != Stitcher::OK){cout << "Can't stitch images, error code = " << status << endl;return -1;}imwrite(result_name, pano);return 0;}void printUsage(){cout <<"Rotation model images stitcher.\n\n""stitching img1 img2 [...imgN]\n\n""Flags:\n"" --try_use_gpu (yes|no)\n""Try to use GPU. The default value is 'no'. All default values\n""are for CPU mode.\n"" --output <result_img>\n""The default is 'result.jpg'.\n";}int parseCmdArgs(int argc, char** argv){if (argc == 1){printUsage();return -1;}for (int i = 1; i < argc; ++i){if (string(argv[i]) == "--help" || string(argv[i]) == "/?"){printUsage();return -1;}else if (string(argv[i]) == "--try_use_gpu") // 默认不使用gpu加速{if (string(argv[i + 1]) == "no")try_use_gpu = false;else if (string(argv[i + 1]) == "yes")try_use_gpu = true;else{cout << "Bad --try_use_gpu flag value\n";return -1;}i++;}else if (string(argv[i]) == "--output") // 若定义了输出图像名，则更改result_name{result_name = argv[i + 1];i++;}else{Mat img = imread(argv[i]);if (img.empty()){cout << "Can't read image '" << argv[i] << "'\n";return -1;}imgs.push_back(img);}}return 0;}
这里在自己的机子上实现简单的图像拼接，程序生成的可执行文件名为imageStitching.exe，如果直接运行程序将直接退出，需要在cmd中进行以下操作：
找到imageStitching.exe所在的目录，在终端里输入imageStitching+被拼接的图像路径（若与imageStitching.exe在同个文件夹，直接输入图像的名字和后缀名即可），如这里输入:imageStitching 1.jpg 2.jpg 3.jpg。
若输入：–output 4.jpg，就会把1.jpg、2.jpg和3.jpg 进行拼接，而输出的文件是imageStitching.exe路径下的4.jpg，由于在例程默认输出为result.jpg，可以不用设置output。
由于选取的图像在拍摄时并不平行，能拼接出这种效果的图像已是不错：
1.jpg：
2.jpg：
3.jpg：
拼接输出结果result.jpg：
代码中使用函数：Stitcher::Status status = stitcher.stitch(imgs, pano);就能得出一个傻瓜拼接结果…如之前所提到的，这其中涉及到很多算法的实现过程，可以看到图像拼接算法是一个值得深入的领域。更多的算法可参考：
/project-updates/makingapanoramapicture
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