convert Bitmap to Mat after capture image using android camera

Question

Mat b = new Mat();
Bitmap bmp = getIntent().getExtras().getParcelable(\"image_send\");

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCr         


        

Answer 1

Utils.bitmapToMat converts an Android Bitmap to an OpenCV Mat. It requires a bitmap of type ARGB_8888 or RGB_565.

import org.opencv.android.Utils;

Mat mat = new Mat();    
Bitmap bmp32 = bmp.copy(Bitmap.Config.ARGB_8888, true);
Utils.bitmapToMat(bmp32, mat);

Answer 2

Mat tmp = new Mat (bmp.getWidth(), bmp.getHeight(), CvType.CV_8UC1);

OpenCV Mat constructor expects rows, cols pair instead of width, height as its arguments, invert them.

Try:

Mat tmp = new Mat (bmp.getHeight(), bmp.getWidth(), CvType.CV_8UC1);

Answer 3

Same problem with my app. In the main activity, I had to render OpenCV utilizable. (I am assuming your app threw a link error when Mat library was used). All sample apps do this. Include this your in main activity.

 private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
        @Override
        public void onManagerConnected(int status) {
            switch (status) {
                case LoaderCallbackInterface.SUCCESS:
                {
                    Log.i("OpenCVManager setup", "OpenCV loaded successfully");
                  //Use openCV libraries after this  
                } break;
                default:
                {
                    super.onManagerConnected(status);
                } break;
            }
        }
    };

    @Override
    public void onResume()
    {
        super.onResume();
        OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_9, this,
                mLoaderCallback);
    }

Answer 4

With Camera2 this task is very fast, only you need config the ImageReader with ImageFormat on YUV_420_888 and then proccess frames with OpenCV like this:

// You can read image with differents patterns for example grayscale:
Mat mGray(height, width, cv::IMREAD_GRAYSCALE, pFrameData); 

A complete implementation in the next answer: https://stackoverflow.com/a/49331546/471690