Computer Vision

Learning openCV

This is the note to show what I have learned when reading “Learning openCV”.

Image

This is a “Hello World” program of OpenCV:

#include <opencv/highgui.h>
#include <opencv/cv.h>
using namespace std;
using namespace cv;

   int main() {
    IplImage* img = cvLoadImage( "/Users/eric/Desktop/test.png" );
    
    //cvNameWindow to create a window, "Example1" is window's name
    cvNamedWindow( "Example1", CV_WINDOW_AUTOSIZE);
    
    //cvShowImage assign a point of Image to the window
    cvShowImage( "Example1", img );
    cvWaitKey(0);
    cvReleaseImage( &img );
    cvDestroyWindow( "Example1" );
}

video

#include <opencv/highgui.h>
#include <opencv/cv.h>
using namespace std;
using namespace cv;
int g_slider_position = 0; CvCapture* g_capture = NULL;
void onTrackbarSlide(int pos) {
cvSetCaptureProperty(g_capture, CV_CAP_PROP_POS_FRAMES, pos);
}

int main() {
    cvNamedWindow( "Example2", CV_WINDOW_AUTOSIZE );
    char * url = "/Users/eric/Desktop/test.mov";
    g_capture = cvCreateFileCapture( url );

int frames = (int) cvGetCaptureProperty(g_capture, CV_CAP_PROP_FRAME_COUNT );
if( frames!= 0 ) {
    cvCreateTrackbar( "Position", "Example2", &g_slider_position, frames, onTrackbarSlide); }
IplImage* frame;
while(1) {
    frame = cvQueryFrame( g_capture );
    if( !frame ) break;
    cvShowImage( "Example2", frame );
    char c = cvWaitKey(33);
    if( c == 27 ) break;
}
cvReleaseCapture( &g_capture );
cvDestroyWindow( "Example2" );
}