stream a webcam image from a c++ opencv dll, through to a c# windows form?

asked 2017-06-12 05:58:08 -0500

antithing gravatar image

updated 2017-06-12 06:34:13 -0500

Hi, as above. I have an opencv dll application that i need to run through a windows forms application. I have this code compiling, but the resulting image is just black. Where am i going wrong here?

//c++ dll code:

    extern "C" {

       cv::Mat frame;
        __declspec(dllexport) void camera()
            cv::VideoCapture cap;
            if (!
                std::cout << "cam not up" << std::endl;

                cap >> frame;

                cv::imshow(":", frame);


        __declspec(dllexport)uchar*  img(void)




//c# form code:

     [DllImport("Cranium.dll", CallingConvention = CallingConvention.Cdecl)]
            public static extern void camera();

            [DllImport("Cranium.dll", CallingConvention = CallingConvention.Cdecl)]
            public static extern IntPtr img();

  private void stream()
            Bitmap a = new Bitmap(640, 480, 3 * 640, PixelFormat.Format24bppRgb, img());
            pictureImg.Image = a;

        private void buttonConnect_Click(object sender, EventArgs e)
             Thread connectThread = new Thread(camera);

            Thread displayThread = new Thread(stream);


When i run buttonConnect, the camera starts, and the c++ window runs fine. But the c# image in teh picturebox stays black.

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It is not an opencv problem. You can use tags in this forum or this one

LBerger gravatar imageLBerger ( 2017-06-12 06:27:27 -0500 )edit

tag added. thank you.

antithing gravatar imageantithing ( 2017-06-12 06:57:33 -0500 )edit

Hello !

This question has been asked for a while. I would like to know if there has been a solution. I am currently experiencing the same problem.


DamVinho gravatar imageDamVinho ( 2020-10-15 10:15:39 -0500 )edit

@DamVinho please ask a new question.first comment is visible only for a few people.

sturkmen gravatar imagesturkmen ( 2020-10-15 10:33:33 -0500 )edit