Add the contents of 2 Mats to another Mat opencv c++

Question

I just want to add the contents of 2 different Mats to 1 other Mat. I tried:

Mat1.copyTo(newMat);
Mat2.copyTo(newMat);

But that just seemed to overwrite the previous contents of the Mat.

This may be a simple question, but I'm lost.

Answer 1

It depends on what you want to add. For example, you have two 3x3 Mat:

cv::Mat matA(3, 3, CV_8UC1, cv::Scalar(20));
cv::Mat matB(3, 3, CV_8UC1, cv::Scalar(80));

You can add matA and matB to a new 3x3 Mat with value 100 using matrix operation:

auto matC = matA + matB;

Or using array operation cv::add that does the same job:

cv::Mat matD;
cv::add(matA, matB, matD);

Or even mixing two images using cv::addWeighted:

cv::Mat matE;
cv::addWeighted(matA, 1.0, matB, 1.0, 0.0, matE);

Sometimes you need to merge two Mat, for example create a 3x6 Mat using cv::Mat::push_back:

cv::Mat matF;
matF.push_back(matA);
matF.push_back(matB);

Even merge into a two-channel 3x3 Mat using cv::merge:

auto channels = std::vector<cv::Mat>{matA, matB};
cv::Mat matG;
cv::merge(channels, matG);

Think about what you want to add and choose a proper function.

Answer 2

You can use push_back():

newMat.push_back(Mat1);
newMat.push_back(Mat2);