How to draw circles with random colors in OpenCV

Question

I am using SURF algorithm to match two images with OpenCV. And I have got the keypioints.

Now I want to draw these keypoints with random colors circles.

I know how to draw a circle in OpenCV with the function cvCircle, but the color is fixed with cvScalar(r,g,b).

I want the the color of the circle of a keypoint in a image is different to the circles near it.

The library function cv::drawMatches() in OpenCV have the effect I want. But I don't know how to realize it.

Does anyone who can tell me how to draw the circles.

Thanks!

Answer 1

Suppose you want to draw circles in different colors on Mat image. Here is a way to generate random colors:

RNG rng(12345);
Mat image = Mat::zeros(500, 500, CV_8UC3);     // change to the size of your image
for (int i = 0; i < circleNum; i++) {
    Scalar color = Scalar(rng.uniform(0,255), rng.uniform(0, 255), rng.uniform(0, 255));
    circle(image, center[i], radius[i], color, -1, 8, 0);
}