app.py

import streamlit as st

with Image.open("kitty.jpeg") as img:
    draw = ImageDraw.Draw(img)

    # Draw an ellipse at each coordinate in points
    for point in st.session_state["points"]:
        coords = get_ellipse_coords(point)
        draw.ellipse(coords, fill="red")

    value = streamlit_image_coordinates(img, key="pil")

    if value is not None:
        point = value["x"], value["y"]

        if point not in st.session_state["points"]:
            st.session_state["points"].append(point)
            st.experimental_rerun()