OpenCV ROI on Real time camera - c++

Question

I am trying to set ROI in real time camera and copy a picture in the ROI.
However, I tried many methods from Internet but it is still unsuccessful.
Part of my code is shown below:
while(!protonect_shutdown)
{
listener.waitForNewFrame(frames);
libfreenect2::Frame *ir = frames[libfreenect2::Frame::Ir];
//! [loop start]
cv::Mat(ir->height, ir->width, CV_32FC1, ir->data).copyTo(irmat);
Mat img = imread("button.png");
cv::Rect r(1,1,100,200);
cv::Mat dstroi = img(Rect(0,0,r.width,r.height));
irmat(r).convertTo(dstroi, dstroi.type(), 1, 0);
cv::imshow("ir", irmat / 4500.0f);
int key = cv::waitKey(1);
protonect_shutdown = protonect_shutdown || (key > 0 && ((key & 0xFF) == 27));
listener.release(frames);
}
My real time camera can show the video normally. And no bugs in my program, but the picture cannot be shown in the ROI.
Does anyone have some ideas?
Any help is appreciate.

Answer 1

I hope I understood your question right and you want an output something like this:
I have created a rectangle of size 100x200 on the video feed and displaying an image in that rectangle.
Here is the code:
int main()
{
Mat frame,overlayFrame;
VideoCapture cap("video.avi");//use 0 for webcam
overlayFrame=imread("picture.jpg");
if (!cap.isOpened())
{
cout << "Could not capture video";
return -1;
}
Rect roi(1,1,100,200);//creating a rectangle of size 100x200 at point (1,1) on the videofeed
namedWindow("CameraFeed");
while ((cap.get(CV_CAP_PROP_POS_FRAMES) + 1) < cap.get(CV_CAP_PROP_FRAME_COUNT))
{
cap.read(frame);
resize(overlayFrame, overlayFrame, resize(overlayFrame, overlayFrame, Size(roi.width, roi.height));//changing the size of the image to fit in the roi
overlayFrame.copyTo(frame(roi));//copying the picture to the roi
imshow("CameraFeed", frame);
if (waitKey(27) >= 0)
break;
}
destroyAllWindows;
return 0;
}