How a smart pen works
A smart pen writes with real ink. A small camera near the tip reads a pattern of tiny dots printed on the paper, so the pen knows which page it is on and where, and sends every stroke to an app over Bluetooth. On ordinary paper it writes like any pen, and nothing is recorded.
Two things follow from that: the page is digital at once, with no photo. And you are tied to the maker's paper, meaning its notebooks or pages you print yourself with the pattern.

