Cant draw a circle to an image

I’m just starting out with OF and have a very beginner question.
I want to draw a circle to an image (say an ofImage) at point xy.

This sounds really simple but I can’t seem to find any information on it. I know how to draw a circle to the main screen but not to an image.
The reason for this is because I want to put a point at the centroid point of my blobs and show the path that they traveled. I don’t think I would have to create an array and draw that array of circles every frame. If I can get the dots drawn to the image I could then save that image every hour to study the path the blobs traveled.

Thanks for your help,
Steve

You can try an fbo. There is an example called fboTrailsExample that would be helpful. Just don’t call ofClear and dont draw the rect if you want to see every frame.