Opencv saves pictures in the specified format

Save the image locally , In the specified format , Need to use cv::imwrite() function

The function prototype ：

bool imwrite(const string& filename, InputArray img, 
             const vector<int>& params=vector<int>() )

Parameter interpretation ：filename: Image saving path , Its suffix Represents the format to be saved .
      img：Mat Variable
      params： For specific formats , You can set some properties . such as , Save as JPEG2000 when , It can be used params Set the compression ratio , And you can set multiple properties at the same time , Just follow paramId_1, paramValue_1, paramId_2, paramValue_2, … . This format .（ It's kind of like matlab Key - It's worth it ）

at present , The supported image formats are
Enclosed Source link , For inquiry, please refer to .

for instance , take png The image is saved as JPEG2000 Format , The compression ratio is 0.5

#include <iostream>
#include <libavutil/avutil.h>
#include <opencv2/highgui.hpp>
#include <opencv4/opencv2/imgproc.hpp>
#include <vector>

using namespace cv;
using namespace std;
int main()
{
    Mat img;
    img  = imread("/home/lfh/ picture / wallpaper / Qinnv .png");
    imshow("image",img);

    vector<int> compression_params;
    compression_params.push_back(IMWRITE_JPEG2000_COMPRESSION_X1000);
    compression_params.push_back(500); //0.5*1000
    imwrite(" Qinnv .jp2",img,compression_params);
    waitKey(0);
}