使用OpenCV 3.0 for Android以任何格式（.jpg，.png）通过按钮单击

Question

我正在使用OpenCV 3.0在Android中制作一个简单的相机应用程序。我读过有关Imgcodecs.imwrite但我无法使用它保存图片。这是我的代码：

private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this)
{
    @Override
    public void onManagerConnected(int status)
    {
        switch (status)
        {
            case LoaderCallbackInterface.SUCCESS:
            {
                mOpenCvCameraView.enableView();
            }
            break;
            default:
            {
                super.onManagerConnected(status);
            }
            break;
        }
    }
};

@Override
protected void onCreate(Bundle savedInstanceState)
{
    //Set Activity layout for Camera Preview
    super.onCreate(savedInstanceState);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    ActionBar actionBar = getSupportActionBar();
    actionBar.hide();
    setContentView(R.layout.activity_camera_home);
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

    //Load Camera Surface
    mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.camera_surface_view);
    mOpenCvCameraView.setVisibility(SurfaceView.VISIBLE);
    mOpenCvCameraView.setCvCameraViewListener(this);

    //Declare Clicking Button parameters
    ImageButton capture = (ImageButton)findViewById(R.id.imageButton);
    final MediaPlayer mp = MediaPlayer.create(this, R.raw.click);

    //Capture Image by Button Click
    capture.setOnClickListener(new View.OnClickListener()
    {
        public void onClick(View v)
        {
            mp.start(); //Play Capture Sound

            //Save Image by Button Click
            sdRoot = Environment.getExternalStorageDirectory();
            dir = "/DCIM/Data Collection/";
            fileName = "IMG_" + new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date()).toString() + ".png";
            File mkDir = new File(sdRoot, dir);
            mkDir.mkdirs();
            File pictureFile = new File(sdRoot, dir + fileName);*/

            Imgcodecs.imwrite("/sdcard/" + dir + fileName,mGray);
        }
    });
}

@Override
public void onPause()
{
    super.onPause();
    if (mOpenCvCameraView != null)
        mOpenCvCameraView.disableView();
}

@Override
public void onResume()
{
    super.onResume();
    if (!OpenCVLoader.initDebug()) {
        OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_0_0, this, mLoaderCallback);
    } else {
        mLoaderCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);
    }
}

public void onDestroy()
{
    super.onDestroy();
    if (mOpenCvCameraView != null)
        mOpenCvCameraView.disableView();
}

public void onCameraViewStarted(int width, int height)
{
    mRgba = new Mat(height, width, CvType.CV_8UC4);
    mIntermediateMat = new Mat(height, width, CvType.CV_8UC4);
    mGray = new Mat(height, width, CvType.CV_8UC1);
}

public void onCameraViewStopped()
{
    mRgba.release();
    mGray.release();
    mIntermediateMat.release();
}

public Mat onCameraFrame(CvCameraViewFrame inputFrame)
{
    mRgba = inputFrame.rgba();
    int maxValue = 255;
    int blockSize = 5;
    int meanOffset = 4;
    Imgproc.adaptiveThreshold(inputFrame.gray(), mIntermediateMat, maxValue, Imgproc.ADAPTIVE_THRESH_MEAN_C, Imgproc.THRESH_BINARY, blockSize, meanOffset);
    Imgproc.cvtColor(mIntermediateMat, mRgba, Imgproc.COLOR_GRAY2RGBA, 4);
    return mRgba;
}

它只是以二进制模式打开相机表面，我想保存二进制图像。