如何在OpenCv C ++中向图像添加图像

Question

I load small image.

 Mat extra;
 extra = imread("Korona.jpg");

I load image from camera and I try add my image.

VideoCapture cap;
Mat frame;
cap >> frame;
cv::Rect roi(cv::Point(0, 0), cv::Size(110, 110));
cv::Mat destinationROI = img(roi);
extra.copyTo(destinationROI(cv::Rect(0, 0, extra.cols, extra.rows)));

But not successful and have this error:

OpenCV Error: Assertion failed (0 <= roi.x && 0 <= roi.width && roi.x + roi.width <= m.cols && 0 <= roi.y && 0 <= roi.height && roi.y + roi.height <= m.rows) in cv::Mat::Mat, file C:\\build\\master_winpack-build-win64-vc14\\opencv\\modules\\core\\src\\matrix.cpp, line 522

Any ideas? Thx.

Answer 1

if(roi.x >= 0 && roi.y >= 0 && roi.width + roi.x < input_frame.cols && roi.height + roi.y < input_frame.rows)
{
    // your code

}
else
    return -1;

Found similar issues and pulled code from here and here

Looking at your code, looks like you don't open your capture

VideoCapture cap(0); //for a webcam
Mat frame;
if(cap.isOpened())
   cap >> frame;
else
   throw;
cv::Rect roi(cv::Point(0, 0), cv::Size(110, 110));
cv::Mat destinationROI = frame(roi);
extra.copyTo(destinationROI(cv::Rect(0, 0, extra.cols, extra.rows)));

Check out OpenCV's documentation on VideoCapture to make sure you're getting that done correctly.