opencv：mat、string、char、uchar转换

柔情只为你懂 2022-11-27 06:50 361阅读 0赞

## cv:mat读取图片并显示 ##

int main()
    {
        
        cv::Mat mat = cv::imread("/home/oceanstar/image/aa.jpg");
        if(mat.empty())
        {
        
            cout << "图像不能加载！"<< endl;
            return -1;
        }
    
        imshow("MyWindow", mat);
        //等待直到有键按下
        waitKey(0);
        return 0;
    }

## char\*转为mat ##

cv::Mat char_to_mat(char *image_buf, int image_len){
        
        cv::Mat mat;
        string str2(image_buf, image_len);
        std::vector<char> vec_data1(str2.c_str(), str2.c_str() + str2.size());
        mat = cv::imdecode(vec_data1, -1).clone();
        return mat;
    }

## char\[\]与mat ##

#include <string>
    #include <iostream>
    #include <time.h>
    #include <opencv2/highgui/highgui.hpp>
    #include <fstream>
    
    using namespace std;
    using namespace cv;
    
    const int MAX = 1024 * 1920 * 3;
    
    
    bool write_image(const string& filename, char  *pBuffer, int length){
        
        ofstream fout(filename, ios::binary);
        if(!fout){
        
            printf("can't open  = %s\n", filename.c_str());
            return false;
        }
        fout.write(pBuffer,length);
        fout.close();
        return true;
    }
    int main()
    {
        
        //3通道图像
        cv::Mat img2 = cv::imread("/home/oceanstar/image/aa.jpg");
        if(img2.empty())
        {
        
            cout << "图像不能加载！"<< endl;
            return -1;
        }
    
        char p[MAX]; //char数组
        std::vector<uchar> buff;
        cv::imencode(".jpg", img2, buff);
        memset(p, 0, MAX);
        memcpy(p, reinterpret_cast<char*>(&buff[0]), buff.size());
        int length = buff.size();
    
        char * buffer = reinterpret_cast<char *>(p);
        write_image("/home/oceanstar/image/vvvv.jpg", buffer, length );
    
        return 0;
    }

## uchar\*与mat ##

#include <string>
    #include <iostream>
    #include <time.h>
    #include <opencv2/highgui/highgui.hpp>
    #include <fstream>
    
    using namespace std;
    using namespace cv;
    
    const int img_width=1920; /** 图像的宽度*/
    const int img_height = 1024; /**图像的高度*/
    
    
    /**将uchar类型的转换为Mat类型*/
    Mat ucharToMat(const uchar *p2)
    {
        
        Mat img(Size(img_width, img_height),CV_8UC3);
        for (int i = 0; i < img_width * img_height * 3; i++)
        {
        
            img.at<Vec3b>(i / (img_width * 3), (i % (img_width * 3)) / 3)[i % 3] = p2[i];
        }
        return img;
    }
    /**数组，存放图片大小*/
    ///uchar p1[img_width * img_height * 3];
    /**将Mat类型的数据转换为uchar类型*/
    uchar* matToUchar(Mat img, uchar *p1)
    {
        
        for (int i = 0; i < img_width * img_height * 3; i++)
        {
        
            p1[i]= (uchar)img.at<Vec3b>(i / (img_width * 3), (i % (img_width * 3)) / 3)[i % 3];
        }
        return p1;
    }
    
    int main()
    {
        
        //3通道图像
        cv::Mat img2 = cv::imread("/home/oceanstar/image/aa.jpg");
        if(img2.empty())
        {
        
            cout << "图像不能加载！"<< endl;
            return -1;
        }
    
        /**定义一个数组存放matToUchar的返回值*/
        auto *p = new uchar[img_width * img_height * 3];
        matToUchar(img2, p);
        /**下面这两行代码目的是输出Mat转化为uchar的值是否正确
        @(int)目的是将uchar类型的数据转换为int可以直观的看到，
        uchar的数据输出的是乱码
        */
       for (int i = 0; i < img_width * img_height * 3; i++){
        
            cout << (int)p[i] << endl;
        }
        Mat img = ucharToMat(p);
        imshow("img",img);
        waitKey(0);
    
        return 0;
    }

# cv::Mat转std::string #

cv::Mat mat = cv::imread("d:\\1.jpg");
    std::string str;
    std::vector<unsigned char> buff;
    cv::imencode(".jpg", mat, buff);
    str.resize(buff.size());
    memcpy(&str[0], buff.data(), buff.size());

[c/c++编程：读取文本&图片转为二进制流][c_c]

[uchar和Mat之间的相互转换][uchar_Mat]  
[c++ string转char\*][c_ string_char]

[c_c]: https://blog.csdn.net/zhizhengguan/article/details/106013828
[uchar_Mat]: https://blog.csdn.net/Black_Friend/article/details/89372976
[c_ string_char]: https://www.cnblogs.com/mdumpling/p/8179167.html