error in apply method in Background subtraction in opencv android

Question

I want to do background subtraction on InputFrame, and want to return foreground mask. I am facing error as bellow can any one help me to fix it Thanks in advance

My Code:

package org.opencv.samples.tutorial1;

import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewFrame;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Mat;
import org.opencv.core.Point;
import org.opencv.core.Scalar;
import org.opencv.video.BackgroundSubtractorMOG;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewListener2;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.SurfaceView;
import android.view.WindowManager;
import android.widget.Toast;

public class Tutorial1Activity extends Activity implements CvCameraViewListener2 {
    private static final String TAG = "Divyesh::Activity";

    private CameraBridgeViewBase mOpenCvCameraView;
    private boolean              mIsJavaCamera = true;
    private MenuItem             mItemSwitchCamera = null;

    public Point p1 = new Point(10, 2);
    public Point p2 = new Point(100, 20);
    public  Scalar scalar = new Scalar(255, 255, 255);
    public Mat fgMask;
    public Mat mRgba, mGray, mRgb;
    //public BackgroundSubtractor pMog, pMog2;
    BackgroundSubtractorMOG pMog;


    private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {

        @Override
        public void onManagerConnected(int status) {
            switch (status) {
                case LoaderCallbackInterface.SUCCESS:
                {
                    Log.i(TAG, "OpenCV loaded successfully");
                    mOpenCvCameraView.enableView();
                } break;
                default:
                {
                    super.onManagerConnected(status);
                } break;
            }
        }
    };


    public Tutorial1Activity() {
        Log.i(TAG, "Instantiated new " + this.getClass());
    }

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        Log.i(TAG, "called onCreate");
        super.onCreate(savedInstanceState);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

        setContentView(R.layout.tutorial1_surface_view);

        if (mIsJavaCamera)
            mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.tutorial1_activity_java_surface_view);
        else
            mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.tutorial1_activity_native_surface_view);

        mOpenCvCameraView.setVisibility(SurfaceView.VISIBLE);

        mOpenCvCameraView.setCvCameraViewListener(this);

    }

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

    @Override
    public void onResume()
    {
        super.onResume();
        OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_3, this, mLoaderCallback);
    }

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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        Log.i(TAG, "called onCreateOptionsMenu");
        mItemSwitchCamera = menu.add("Toggle Native/Java camera");
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        String toastMesage = new String();
        Log.i(TAG, "called onOptionsItemSelected; selected item: " + item);

        if (item == mItemSwitchCamera) {
            mOpenCvCameraView.setVisibility(SurfaceView.GONE);
            mIsJavaCamera = !mIsJavaCamera;

            if (mIsJavaCamera) {
                mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.tutorial1_activity_java_surface_view);
                toastMesage = "Java Camera";
            } else {
                mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.tutorial1_activity_native_surface_view);
                toastMesage = "Native Camera";
            }

            mOpenCvCameraView.setVisibility(SurfaceView.VISIBLE);
            mOpenCvCameraView.setCvCameraViewListener(this);
            mOpenCvCameraView.enableView();
            Toast toast = Toast.makeText(this, toastMesage, Toast.LENGTH_LONG);
            toast.show();
        }

        return true;
    }

    public void onCameraViewStarted(int width, int height) {
        mRgba = new Mat();
        mGray = new Mat();
        mRgb = new Mat();
        fgMask = new Mat();
        Log.i(TAG, "Before subtractor");
        pMog = new BackgroundSubtractorMOG();
    }

    public void onCameraViewStopped() {
    }

    public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
        Log.i(TAG, "Before input frame");
        mRgba = inputFrame.rgba();
        //Imgproc.cvtColor(mRgba, mRgb, Imgproc.COLOR_RGBA2RGB);
        Log.i(TAG,"Before apply");
        pMog.apply(mRgba, fgMask);
        Log.i(TAG,"After apply");
        //Imgproc.cvtColor(fgMask, mRgba, Imgproc.COLOR_GRAY2RGBA);
        return fgMask;

    }
}

My error is at here:

/** *

Computes a foreground mask.

* * @param image Next video frame. * @param fgmask The output foreground mask as an 8-bit binary image. * * @see org.opencv.video.BackgroundSubtractor.operator() */

public  void apply(Mat image, Mat fgmask)
{

    apply_1(nativeObj, image.nativeObj, fgmask.nativeObj);

    return;
}

Thanx a lot if you can solve it or can give some instruction...........

I m getting blank screen at run time.... but frame are still receiving according to LOGs — user3530702
that might be unpleasant, but not a real error. a model has to get trained there, you usually don't get the correct result in the 1st frame returned. play with params like history. — berak

udit7395 udit7395 · Accepted Answer · 2014-11-22T14:35:34

I haven't used or worked with Background Subtraction before but try this following edit in your code.

mRgba = inputFrame.rgba();
Imgproc.cvtColor(mRgba, mRgb, Imgproc.COLOR_RGBA2BGR,4);
Log.i(TAG,"Before apply");
pMog.apply(mRgb, fgMask);
Log.i(TAG,"After apply");
Imgproc.cvtColor(fgMask, mRgb, Imgproc.COLOR_GRAY2BGR,3);
Imgproc.cvtColor(mRgb, mRgba, Imgproc.COLOR_BGR2RGBA,4);
return fgMask;

Also check this link. I think it might help:http://www.codeproject.com/Articles/791145/Motion-Detection-in-Android-Howto

Hope this helps.

error in apply method in Background subtraction in opencv android

1 Answers