OPENCV(3) —— 对XML和YAML文件实现I/O 操作

XMLYAML文件在OpenCV中的数据结构为FileStorage

string filename = "I.xml";
FileStorage fs(filename, FileStorage::WRITE);
\...
fs.open(filename, FileStorage::READ);

fs.release();

写入文件使用  <<  运算符 ，读取文件，使用 >> 运算符

fs << "iterationNr" << 100;

int itNr;
fs["iterationNr"] >> itNr;
itNr = (int) fs["iterationNr"];

OpenCV 数据结构的输入和输出

Mat R = Mat_<uchar >::eye (3, 3),
T = Mat_<double>::zeros(3, 1);
fs << "R" << R; // Write cv::Mat
fs << "T" << T;
fs["R"] >> R; // Read cv::Mat
fs["T"] >> T;

vector要注意在第一个元素前加上“[”，在最后一个元素前加上"]"

fs << "strings" << "["; // text - string sequence
fs << "image1.jpg" << "Awesomeness" << "baboon.jpg";
fs << "]"; // close sequence

对于map结构的操作使用的符号是"{"和"}"

fs << "Mapping"; // text - mapping
fs << "{" << "One" << 1;
fs << "Two" << 2 << "}";

读取这些结构的时候，会用到FileNode和FileNodeIterator数据结构。对FileStorage类的[]操作符会返回FileNode数据类型，对于一连串的node，可以使用FileNodeIterator结构

FileNode n = fs["strings"]; // Read string sequence - Get node
if (n.type() != FileNode::SEQ)
{
cerr << "strings is not a sequence! FAIL" << endl;
return 1;
}
FileNodeIterator it = n.begin(), it_end = n.end(); // Go through the node
for (; it != it_end; ++it)
cout << (string)*it << endl;

<?xml version="1.0"?>
<opencv_storage>
<depthImg190 type_id="opencv-image">
<width>320</width>
<height>240</height>
<origin>top-left</origin>
<layout>interleaved</layout>
<dt>w</dt>
<data>
0 0 0 0 27120 27384 27120 27120 27384 27120 27120 27120 27120 27384
27384 27664 27664 27944 27944 27664 27664 27944 27944 27944 28224
27944 27944 28224 28224 28224 28224 28520 28816 29120 29120 29120
29120 29120 29120 29120 29432 29744 30072 30072 29744 29744 30072
30072 30072 30400 30400 30736 30736 31080 31080 31080 31440 31440
31440 31440 31800 31800 31800 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 27120 27120 27120 27120 27384 27384 27384 27384 27384 27384
</depthImg190>
</opencv_storage>

这种格式不能直接使用xml，而需要

IplImage* depth=(IplImage*)cvLoad("depthImg190.xml");

cvLoad 函数

const char* filename = "zhang.jpg";

    std::ifstream file(filename);
    std::vector<char> data;

    file >> std::noskipws;    // noskipws 不忽略空白
    std::copy(std::istream_iterator<char>(file), std::istream_iterator<char>(), std::back_inserter(data));


    cv::Mat matrixJprg = cv::imdecode(cv::Mat(data), 1);
    IplImage qImg;
    qImg = IplImage(matrixJprg); // cv::Mat -> IplImage 可以直接强制转换

    cvSaveImage("./out.jpg", &qImg);

cvSaveImage 直接把 cv::Mat 数据保存为图片会出现问题，需要以上的代码强制转换