OpenCV unable to capture image from isight webcam

Question

I can not capture image from my webcam using following OpenCV code.

The code can show images from a local AVI file or a video device. It works fine on a "test.avi" file.

When I make use my default webcam(CvCapture* capture =cvCreateCameraCapture(0)), the program can detected the size of the image from webcam,but just unable to display the image .

/ I forgot to mention that I can see the iSight is working because the LED indicator is turn on /

Anyone encounter the same problem?

cvNamedWindow( "Example2", CV_WINDOW_AUTOSIZE );

CvCapture* capture =cvCreateFileCapture( "C:\\test.avi" ) ;// display images from avi file, works well 
// CvCapture* capture =cvCreateCameraCapture(0); //display the frame(images) from default webcam not work 

assert( capture );
IplImage* image;

while(1) {
 image = cvQueryFrame( capture );
   if( !image ) break;

  cvShowImage( "Example2", image );

  char c = cvWaitKey(33);
  if( c == 27 ) break;
}

cvReleaseCapture( &capture );
cvDestroyWindow( "Example2" );

• opencv 2.2
• Debug library *d.lib
• WebCam isight
• Macbook OS win7 32
• VS2008

Answer 1

I'm working on opencv 2.3 with Macbook pro Mid 2012 and I had that problem with the Isight cam. Somehow I managed to make it work on opencv by simply adjusting the parameters of the Cvcapture and adjusting the frame width and height:

CvCapture* capture = cvCaptureFromCAM(0);
cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH, 500 );
cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT, 600 );

You can also change these numbers to the frame width and height you want.

Answer 2

Try this:

int main(int, char**) {
    VideoCapture cap(0); // open the default camera
    if (!cap.isOpened()) {  // check if we succeeded
        cout << "===couldn't open camera" << endl;
        return -1;
    }
    Mat edges, frame;
    frame = cv::Mat(10, 10, CV_8U);
    namedWindow("edges", 1);
    for (;;) {
        cap >> frame; // get a new frame from camera
        cout << "frame size: " << frame.cols << endl;
        if (frame.cols > 0 && frame.rows > 0) {
            imshow("edges", frame);
        }
        if (waitKey(30) >= 0)
            break;
    }
    // the camera will be deinitialized automatically in VideoCapture destructor
    return 0;
}

Answer 3

Did you try the example from the opencv page ?

namely,

#include "cv.h"
#include "highgui.h"

using namespace cv;

int main(int, char**)
{
    VideoCapture cap(0); // open the default camera
    if(!cap.isOpened())  // check if we succeeded
        return -1;

    Mat edges;
    namedWindow("edges",1);
    for(;;)
    {
        Mat frame;
        cap >> frame; // get a new frame from camera
        cvtColor(frame, edges, CV_BGR2GRAY);
        GaussianBlur(edges, edges, Size(7,7), 1.5, 1.5);
        Canny(edges, edges, 0, 30, 3);
        imshow("edges", edges);
        if(waitKey(30) >= 0) break;
    }
    // the camera will be deinitialized automatically in VideoCapture destructor
    return 0;
}

Works on a macbook pro for me (although on OS X). If it doesn't work, some kind of error message would be helpful.

Answer 4

Latest update! Problem solved!

This happen to be one of OpenCV 2.2′s bug

Here is how to fix it:

http://dusijun.wordpress.com/2011/01/11/opencv-unable-to-capture-image-from-isight-webcam/

Answer 5

Why dont you try

capture=cvCaptureFromCam(0);

I think this may work.

Let me know about wheather its working or not.