cv::Mat图像操作

图像读写

//include  header
#include <opencv2/imgcodecs.hpp>

/**
Currently, the following file formats are supported:
Windows bitmaps - *.bmp, *.dib (always supported)
JPEG files - *.jpeg, *.jpg, *.jpe (see the Note section)
JPEG 2000 files - *.jp2 (see the Note section)
Portable Network Graphics - *.png (see the Note section)
WebP - *.webp (see the Note section)
Portable image format - *.pbm, *.pgm, *.ppm *.pxm, *.pnm (always supported)
Sun rasters - *.sr, *.ras (always supported)
TIFF files - *.tiff, *.tif (see the Note section)
OpenEXR Image files - *.exr (see the Note section)
Radiance HDR - *.hdr, *.pic (always supported)
Raster and Vector geospatial data supported by GDAL (see the Note section)
*/
Mat cv::imread	(	const String & 	filename,
int 	flags = IMREAD_COLOR 
);
bool cv::imwrite	(	const String & 	filename,
InputArray 	img,
const std::vector< int > & 	params = std::vector< int >() 
);

图像ROI选取

cv::Mat roi=frame(cv::Rect(x, y, roi_WIDTH, roi_HEIGHT));

图像多通道分离合并

//include header
#include <opencv2/core.hpp>
/**
void cv::split	(	const Mat & 	src,
Mat * 	mvbegin 
);
void cv::merge	(	const Mat * 	mv,
size_t 	count,
OutputArray 	dst 
);
*/
cv::Mat  src,dst;
std::vector<cv::Mat> imgplanes;
cv::split(src,imgplanes);
cv::merge(imgplanes,imgplanes.size(),dst);

图像串联组合

cv::Mat img_encode, img_encode1, img_encode2;
//水平串联
cv::hconcat(img_camera[0], img_camera[1], img_encode1);
cv::hconcat(img_camera[2], img_camera[3], img_encode2);
//垂直串联
cv::vconcat(img_encode1, img_encode2, img_encode);

Camera实时数据/视频回放

Camera实时数据

#include <opencv2/core.hpp>
#include <opencv2/videoio.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>
#include <stdio.h>
using namespace cv;
using namespace std;
int main(int, char**)
{
    Mat frame;
    //--- INITIALIZE VIDEOCAPTURE
    VideoCapture cap;
    // open the default camera using default API
    // cap.open(0);
    // OR advance usage: select any API backend
    int deviceID = 0;             // 0 = open default camera
    int apiID = cv::CAP_ANY;      // 0 = autodetect default API
    // open selected camera using selected API
    cap.open(deviceID, apiID);
    // check if we succeeded
    if (!cap.isOpened()) {
        cerr << "ERROR! Unable to open camera\n";
        return -1;
    }
    //--- GRAB AND WRITE LOOP
    cout << "Start grabbing" << endl
        << "Press any key to terminate" << endl;
    for (;;)
    {
        // wait for a new frame from camera and store it into 'frame'
        cap.read(frame);
        // check if we succeeded
        if (frame.empty()) {
            cerr << "ERROR! blank frame grabbed\n";
            break;
        }
        // show live and wait for a key with timeout long enough to show images
        imshow("Live", frame);
        if (waitKey(5) >= 0)
            break;
    }
    // the camera will be deinitialized automatically in VideoCapture destructor
    return 0;
}

视频回放

cv::VideoCapture capture(videoPath);
for (;;)
{
   capture >> frame;
}