public void takePicture() {
    Log.i(CaptureActivity.TAG, "MyCameraView, takePicture()");
    // Postview and jpeg are sent in the same buffers if the queue is not empty when performing a capture.
    // Clear up buffers to avoid mCamera.takePicture to be stuck because of a memory issue
    mCamera.setPreviewCallback(null);

    // PictureTakenListener is implemented by the current class
    mCamera.takePicture(null, null, this);
}

@Override
public void onPictureTaken(byte[] bytes, Camera camera) {
    // The camera preview was automatically stopped. Start it again.
    mCamera.startPreview();
    mCamera.setPreviewCallback(this);

    Mat mat = Imgcodecs.imdecode(new MatOfByte(bytes), Imgcodecs.CV_LOAD_IMAGE_UNCHANGED);
    Log.d(CaptureActivity.TAG, mat.toString());

    //an interface method to be implemented by CaptureActivity
    if (mPictureTakenListener != null)
        mPictureTakenListener.receivePicture(mat);
}

@Override
public void receivePicture(Mat mat) {
    File path = new File(Environment.getExternalStorageDirectory() + "/myCamera/");
    path.mkdirs();
    File file = new File(path, System.currentTimeMillis() + "recieved" + ".png");
    String filename = file.toString();
    Log.d(CaptureActivity.TAG, "was imwrite a success? "
        + Imgcodecs.imwrite(filename, mat));
}

public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
        Log.d(TAG, "frame info " + frame.toString());
        return frame;
    }