Sometimes, sometimes just optical, but in any case, there's even a guy, Ken Sherriff, who has been doing this as a hobby for ages. It's not like this is merely

Sometimes, sometimes just optical, but in any case, there's even a guy, Ken Sherriff, who has been doing this as a hobby for ages. It's not like this is merely theoretical. https://www.righto.com/search/label/reverse-engineering https://www.righto.com/search/label/reverse-engineering