OpenCv Camera View providing Mat object getting wrong data

Question

I am trying to develop an augmented reality app for android using OpenCv4android. I need to process the camera frame buffers. To see what is the content of the frame buffer matrix, I converted the Mat object to Bitmap and wrote a png image. What I got is just a big chunk of green pixel. Camera buffer should be ok cause opencv is rendering it ok. My code is given below.

public class OpenGLSurfaceWithCameraTest extends Activity implements CvCameraViewListener2{


private static final String  TAG = "OpenGLSurfaceWithCamera";
Mat mRgba;

boolean flag = true;

private CameraBridgeViewBase cameraPreview;

private BaseLoaderCallback  mLoaderCallback = new BaseLoaderCallback(this) {
    @Override
    public void onManagerConnected(int status) {
        switch (status) {
            case LoaderCallbackInterface.SUCCESS:
            {
                Log.i(TAG, "OpenCV loaded successfully");
                cameraPreview.enableView();
            } break;
            default:
            {
                super.onManagerConnected(status);
            } break;
        }
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.camera_with_opengl);


    cameraPreview = (CameraBridgeViewBase)findViewById(R.id.camera_view_opengl);


    cameraPreview.setCvCameraViewListener(this);

}

@Override
protected void onDestroy() {
    // TODO Auto-generated method stub
    super.onDestroy();
}

@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    if(cameraPreview != null){
        cameraPreview.disableView();
    }
}

@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();
    OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_3, this, mLoaderCallback);
}

@Override
public void onCameraViewStarted(int width, int height) {
    // TODO Auto-generated method stub
    mRgba =  new Mat(height, width, CvType.CV_8UC4);
}

@Override
public void onCameraViewStopped() {
    // TODO Auto-generated method stub
    mRgba.release();

}

@Override
public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
    // TODO Auto-generated method stub
    mRgba = inputFrame.rgba();


    Mat tmp = new Mat(mRgba.rows(), mRgba.cols(), CvType.CV_8UC1, new Scalar(4));
    Imgproc.pyrDown(mRgba, tmp);
    Imgproc.pyrDown(tmp, tmp);


    Bitmap bitmap = Bitmap.createBitmap(tmp.cols(), tmp.rows(), Config.ARGB_8888);

    Utils.matToBitmap(tmp, bitmap);

    if(flag){
    try {
        File root = null;
        String state = Environment.getExternalStorageState();
        if(state.equals(Environment.MEDIA_MOUNTED)){
            root = new File(Environment.getExternalStorageDirectory(), "aqib");
            if(root == null){
                Log.e(TAG, "root is null");
            }
            if(!root.exists()){
                root.mkdirs();
            }
        }

        if(root.exists()){
            Log.e(TAG, "root exists");
        }
        File file = new File(root, "test.png");
        OutputStream stream = new FileOutputStream(file);
        bitmap.compress(Bitmap.CompressFormat.PNG, 90, stream);
        stream.close();
        flag = false;
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        Log.e(TAG, e.getMessage());
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

    bitmap.recycle();
    return mRgba;
}

}

Can anyone suggest me how to get correct output of the camera frame buffer so that I can use it for processing in opengl?

Answer 1

Apparently the first frame is always a green frame in my case. Tried writing the frames from later like 10th or something like that, and it worked.