Generate random numbers matrix in OpenCV

Question

I want to know how can I generate a matrix of random numbers of any given size, for example 2x4. Matrix should consists of signed whole number in range, for example [-500, +500].

I have read the documentation of RNG, but I am not sure on how I should use this. I referred too this question but this did not provide me the solution I am looking for.

I know this might be a silly question, but any help on it would be truly appreciated.

Answer 1

If you want values to be uniformly distributed, you can use cv::randu

Mat1d mat(2, 4); // Or: Mat mat(2, 4, CV_64FC1);
double low = -500.0;
double high = +500.0;
randu(mat, Scalar(low), Scalar(high));

Note that the upper bound is exclusive, so this example represents data in range [-500, +500).

---

If you want values to be normally distributed, you can use cv::randn

Mat1d mat(2, 4); // Or: Mat mat(2, 4, CV_64FC1);
double mean = 0.0;
double stddev = 500.0 / 3.0; // 99.7% of values will be inside [-500, +500] interval
randn(mat, Scalar(mean), Scalar(stddev));

---

This works for matrices up to 4 channels, e.g.:

Mat3b random_image(100,100);
randu(random_image, Scalar(0,0,0), Scalar(256,256,256));