opencv saving image captured from webcam

Question

I receive an error "SIGABRT ERROR" when the code is trying to save the image on the HD.

I'm working with a MacBook Pro Mountain Lion on last XCODE and the libraries are well reconfigured.

Someone has a solution or some ideas?

#include "cv.h"
#include "highgui.h"
#include <stdio.h>
using namespace cv;
// A Simple Camera Capture Framework
int main() {

    CvCapture* capture = cvCaptureFromCAM( CV_CAP_ANY );
    if ( !capture ) {
        fprintf( stderr, "ERROR: capture is NULL \n" );
        getchar();
        return -1;
                     }
    // Create a window in which the captured images will be presented
    cvNamedWindow( "mywindow", CV_WINDOW_AUTOSIZE );
    // Show the image captured from the camera in the window and repeat
    while ( 1 ) {
        // Get one frame
        IplImage* frame = cvQueryFrame( capture );
        if ( !frame ) {
            fprintf( stderr, "ERROR: frame is null...\n" );
            getchar();
            break;
        }
        cvShowImage( "mywindow", frame );
        // Do not release the frame!

        if ( (cvWaitKey(10) & 255) == 's' ) {
            CvSize size = cvGetSize(frame);
            IplImage* img= cvCreateImage(size, IPL_DEPTH_16S, 1);
            img = frame;
             cvSaveImage("matteo.jpg",&img);
                                            }
     if ( (cvWaitKey(10) & 255) == 27 ) break;
    }
    // Release the capture device housekeeping
    cvReleaseCapture( &capture );
    cvDestroyWindow( "mywindow" );
    return 0;
}

Solution

The problem is that you are mixing your pointer syntax. You are creating a new IplImage with IplImage* img= cvCreateImage(size, IPL_DEPTH_16S, 1); but on the following line, you lose this structure as you overwrite the pointer img with frame.

The code causing your sigabrt is where you're sending a pointer to a pointer in cvSaveImage("matteo.jpg",&img);. You should not do &img as img already is a pointer. The following is correct:

cvSaveImage("matteo.jpg",img);

There is actually no reason for you to create a new IplImage unless you want to do some preprocessing before saving it to file.

I modified your if-clause to the following which works fine on my computer:

if ( cvWaitKey(10) < 0 ) {
    cvSaveImage("matteo.jpg",frame);
}