How to clear the cv::Mat contents?

Question

I have a cv::Mat but I have already insert it with some values, how do I clear the contents in it?

Thank you

Answer 1

If you want to release the memory of the Mat variable use release().

Mat m; // initialize m or do some processing m.release(); 

For a vector of cv::Mat objects you can release the memory of the whole vector with myvector.clear().

std::vector<cv::Mat> myvector; // initialize myvector ..   myvector.clear(); // to release the memory of the vector 

Answer 2

From the docs:

// sets all or some matrix elements to s Mat& operator = (const Scalar& s); 

then we could do

m = Scalar(0,0,0); 

to fill with black pixels. Scalar has 4 components, the last - alpha - is optional.