How to accurately determine the center of the pupil of the eye in the photo?

Question

OpenCV

Open cv has standard methods that allow you to determine a person's face in a photo and eyes.
haarcascade_eye.xml
haarcascade_frontalface_default.xml
But this is not enough to determine the center of the pupil,
How would you make the determination of the center of the pupil more accurate using Open CV?

Answer 1

As far as I understand, standard methods produce tuples with x,y,w,h.
Then you can binarize (or highlight the boundaries) of the found rectangles and search for circles (circles) using Hough.