Overlay Image in OpenCV - c++

Question

I am trying to overlay an image over the video capture of my program with OpenCV but I am having trouble getting it to work. I set the a region of interest in the original frame taken from the webcam in the form of a rectangle. Then i copy it to the original frame. However it never shows up on the new frame captured by the webcam. I tested it and the image is loading correctly but it is not being copied to the new frame for some reason.
Code Below in C++:
#include<opencv2/core/core.hpp>
#include<opencv2/contrib/contrib.hpp>
#include<opencv2/highgui/highgui.hpp>
#include<opencv2/imgproc/imgproc.hpp>
#include<iostream>
#include<vector>
using namespace std;
using namespace cv;
int main(){
VideoCapture cap;
cap.open(0);
if(!cap.isOpened()){
cerr << "Error opening the webcam!" << endl;
return -1;
}
for(;;){
Mat frame;
cap>>frame;
Mat newFrame;
frame.copyTo(newFrame);
Mat image = imread("C:\\User\\Desktop\\images\\image.png");
int cx = (newFrame.cols - 70) / 2;
if (image.data) {
// Get a BGR version of the face, since the output is BGR color
Mat srcBGR = Mat(face.size(), CV_8UC3);
cvtColor(image, srcBGR, CV_GRAY2BGR);
// Get the destination ROI (and make sure it is within the image)
Rect dstRC = Rect(cx, newFrame.rows/2, 70, 70);
Mat dstROI = newFrame(dstRC);
// Copy the pixels from src to dst.
srcBGR.copyTo(dstROI);
}
imshow("frame", newFrame);
char key = (char) waitKey(30);
// Exit this loop on escape:
if(key == 27)
break;
}
return 0;
}
Any suggestions or help would be appreciated. Thanks.

Answer 1

You converted image to BGR by using not converted one:
change this: image.copyTo(dstROI); to this srcBGR.copyTo(dstROI);
#include<opencv2/core/core.hpp>
#include<opencv2/contrib/contrib.hpp>
#include<opencv2/highgui/highgui.hpp>
#include<opencv2/imgproc/imgproc.hpp>
#include<iostream>
#include<vector>
using namespace std;
using namespace cv;
int main(){
VideoCapture cap;
cap.open(0);
if(!cap.isOpened()){
cerr << "Error opening the webcam!" << endl;
return -1;
}
Mat image = imread("D:\\ImagesForTest\\Lena.jpg",0);
cv::resize(image,image,Size(70,70));
Mat frame;
for(;;){
cap>>frame;
Mat newFrame=frame.clone();
int cx = (newFrame.cols - 70) / 2;
if (!image.empty()) {
// Get a BGR version of the face, since the output is BGR color
Mat srcBGR = Mat(image.size(), CV_8UC3);
cvtColor(image, srcBGR, CV_GRAY2BGR);
// Get the destination ROI (and make sure it is within the image)
Rect dstRC = Rect(cx, newFrame.rows/2, 70, 70);
Mat dstROI = newFrame(dstRC);
// Copy the pixels from src to dst.
srcBGR.copyTo(dstROI);
}
imshow("frame", newFrame);
char key = (char) waitKey(30);
// Exit this loop on escape:
if(key == 27)
break;
}
return 0;
}