title: Issue with taking a picture by using opencv?
body: <p>I am trying to take a picture from a camera frame using OpenCV in android and save it to the disk. But for some reason when i click on the button, nothing happens. I am really clueless as how I should go about it.</p>
  
  <pre><code> b1.setOnClickListener(new View.OnClickListener() {
              @Override
              public void onClick(View v) {
               Imgcodecs.imwrite("test.jpg",mrgba);
  
               }
          });
  
  
    @Override
      public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
  
          mrgba = inputFrame.rgba();
  
          // Imgproc.cvtColor(mrgba,mgray,Imgproc.COLOR_RGB2GRAY);
         // Imgproc.Canny(mgray,mcanny,50,150);
          DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
          float dpHeight = displayMetrics.heightPixels / displayMetrics.density;
          float dpWidth = displayMetrics.widthPixels / displayMetrics.density;
          float h = mrgba.cols();
          float w = mrgba.rows();
  
  
          int centerx = (int) (mrgba.width()*0.5);
          int  centery = (int) (mrgba.height() * 0.5);
          Rect rect = new Rect(centerx,centery,100,100);
  
          Imgproc.circle(mrgba,new Point(centerx,centery),200,new Scalar(255,0,0),10);
          //Imgproc.resize(mrgba,mrgba,new Size(mrgba.width()*0.3,mrgba.height()*0.3));
  
          return mrgba;
      }
  </code></pre>