app.py

import streamlit as st

def hola():
    st.write("HOLA")

img_file_buffer = st.camera_input("Take a picture", label_visibility="hidden", on_change=hola)

#if img_file_buffer is not None:
# To read image file buffer as bytes:
bytes_data = img_file_buffer.getvalue()
# Check the type of bytes_data:
# Should output: <class 'bytes'>
st.write(type(bytes_data))