i found this program ,i would save the image after counter detection but i just found the original image saved .

edit

package com.example.essai;

import java.io.File; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Date; import java.util.List; import java.util.Locale;

import android.app.Activity; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.net.Uri; import android.os.Bundle; import android.os.Environment; import android.provider.MediaStore; import android.util.Log; import android.view.Menu; import android.view.MenuItem; import android.widget.Button; import android.widget.ImageView; import android.widget.Toast; import android.view.View;

import org.opencv.android.BaseLoaderCallback; import org.opencv.android.LoaderCallbackInterface; import org.opencv.android.OpenCVLoader; import org.opencv.android.Utils; import org.opencv.core.CvType; import org.opencv.core.Mat; import org.opencv.core.MatOfPoint; import org.opencv.core.Scalar; import org.opencv.imgproc.Imgproc;

public class MainActivity extends Activity {

private static final int CAMERA_CAPTURE_IMAGE_REQUEST_CODE = 100;
public static final int MEDIA_TYPE_IMAGE = 1;
private static final String IMAGE_DIRECTORY_NAME = "OpenCV Demo";
private Uri fileUri;
private ImageView imgPreview;
private Button btnCapturePicture;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (!OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_1_0, this, mOpenCVCallBack))
    {
        Log.e("TEST", "Cannot connect to OpenCV Manager");
    }
    setContentView(R.layout.activity_main);

// imgPreview = (ImageView) findViewById(R.id.imgPreview); // btnCapturePicture = (Button) findViewById(R.id.btnCapturePicture); //
// btnCapturePicture.setOnClickListener(new View.OnClickListener() { //
// @Override // public void onClick(View v) { // // capture picture // captureImage(); // } // }); }

private void captureImage() {
    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

    fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE);

    intent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri);

    // start the image capture Intent
    startActivityForResult(intent, CAMERA_CAPTURE_IMAGE_REQUEST_CODE);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // if the result is capturing Image
    if (requestCode == CAMERA_CAPTURE_IMAGE_REQUEST_CODE) {
        if (resultCode == RESULT_OK) {
            // successfully captured the image
            // display it in image view
            previewCapturedImage();
        } else if (resultCode == RESULT_CANCELED) {
            // user cancelled Image capture
            Toast.makeText(getApplicationContext(),
                    "User cancelled image capture", Toast.LENGTH_SHORT)
                    .show();
        } else {
            // failed to capture image
            Toast.makeText(getApplicationContext(),
                    "Sorry! Failed to capture image", Toast.LENGTH_SHORT)
                    .show();
        }
    }
}
private void previewCapturedImage() {
    try {
        imgPreview.setVisibility(View.VISIBLE);

        // bimatp factory
        BitmapFactory.Options options = new BitmapFactory.Options();

        // downsizing image as it throws OutOfMemory Exception for larger
        // images
        options.inSampleSize = 8;

        final Bitmap bitmap = BitmapFactory.decodeFile(fileUri.getPath(),
                options);

        Mat tmp = new Mat(bitmap.getWidth(), bitmap.getHeight(), CvType.CV_8UC1);
        Utils.bitmapToMat(bitmap, tmp);
        Mat gray = new Mat(bitmap.getWidth(), bitmap.getHeight(), CvType.CV_8UC1);
        Imgproc.cvtColor(tmp, gray, Imgproc.COLOR_RGB2GRAY);
        Imgproc.Canny(gray, gray, 50, 200);
        List<MatOfPoint> contours = new ArrayList<MatOfPoint>();
        Mat hierarchy = new Mat();
        // find contours:
        Imgproc.findContours(gray, contours, hierarchy, Imgproc.RETR_TREE,Imgproc.CHAIN_APPROX_SIMPLE);
        for (int contourIdx = 0; contourIdx < contours.size(); contourIdx++) {
            Imgproc.drawContours(tmp, contours, contourIdx, new Scalar(0, 0, 255), -1);
        }
        Utils.matToBitmap(gray, bitmap);
        imgPreview.setImageBitmap(bitmap);
    } catch (NullPointerException e) {
        e.printStackTrace();
    }

}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}


private BaseLoaderCallback  mOpenCVCallBack = new BaseLoaderCallback(this) {
    @Override
    public void onManagerConnected(int status) {
        switch (status) {
                case LoaderCallbackInterface.SUCCESS:
                {
                    Log.e("TEST", "Success");
                    imgPreview = (ImageView) findViewById(R.id.imgPreview);
                    btnCapturePicture = (Button) findViewById(R.id.btnCapturePicture);

                    btnCapturePicture.setOnClickListener(new ...