OpenCv with Android Camera Surfaceview

Question

I am trying to develop an image recognition android application... I am using the customized camera using surface view.... As Herein android to capture images ... I want to process the captured images using opencv , how can i get the captured image and convert it to mat ? also is there a way to save the captured image Temporary ? thanks in advance

Answer 1

I assume that you have added opencv library to your project successfully.

Here is a sample code using OpenCV4android.

public class SampleCameraFrameAccessActivity extends Activity implements        CvCameraViewListener2, OnTouchListener{
private static final String  TAG = "SampleCameraFrameAccessActivity";

protected CameraBridgeViewBase cameraPreview;
protected Mat mRgba;

protected BaseLoaderCallback  mLoaderCallback = new BaseLoaderCallback(this) {
    @Override
    public void onManagerConnected(int status) {
        switch (status) {
            case LoaderCallbackInterface.SUCCESS:
            {
                Log.i(TAG, "OpenCV loaded successfully");
//                    mOpenCvCameraView.enableView();
//                    mOpenCvCameraView.setOnTouchListener(ColorRegionDetectionActivity.this);
                cameraPreview.enableView();
            } break;
            default:
            {
                super.onManagerConnected(status);
            } break;
        }
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.camera_sample_layout);

    cameraPreview = (CameraBridgeViewBase) findViewById(R.id.sample_test_camera_view);

    cameraPreview.setCvCameraViewListener(this);

}

@Override
protected void onDestroy() {
    // TODO Auto-generated method stub
    super.onDestroy();
}

@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    if(cameraPreview != null){
        cameraPreview.disableView();
    }
}

@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();
    OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_3, this, mLoaderCallback);
}

@Override
public void onCameraViewStarted(int width, int height) {
    // TODO Auto-generated method stub
    mRgba =  new Mat(height, width, CvType.CV_8UC4);
}

@Override
public void onCameraViewStopped() {
    // TODO Auto-generated method stub
    mRgba.release();

}

@Override
public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
    // TODO Auto-generated method stub
    mRgba = inputFrame.rgba();

    return mRgba;
}

@Override
public boolean onTouch(View v, MotionEvent event) {
    // TODO Auto-generated method stub
    return false;
}

}

And the XML Layout file is :

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/sample_test_layout" >

    <org.opencv.android.JavaCameraView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/sample_test_camera_view" />

</RelativeLayout>

In onCameraFrame method you can access every frame from the frame buffer of the camera. if you want to capture an image you can add a button and take a particular frame from the buffer and process it. The frame is given as Mat object by default.So you don't have to convert it. after processing, if you need it to converted into bitmap, you can call Utils.matToBitmap(mat, bmp); method to do that.