Best way to high light areas on a picture

Looking for advice on the best way to handle this:

Have a main picture and I want to high light certain areas (around 30) on the picture. I would like to high light with a round circle, and that circle would be transparent with the outline of the circle being either red or green base on some logic.

So would I just show the main image as the form background and then have the 30 circles hidden, and then show them when I do the logic for either red or green for each circle?